HOTO

L ITH PHY

G E ORG FR ITZ

V ice-director of th e Court and Imperial S tate Printing Works at V ienna

T RA N S LA T E D BY

IL J.

'

VVAJQL

(F ellow of the R oyal Pho tograph ic So ciety)

A u th or of The D ictionary of P ho tography ,

”

Carbon P rin ting , e tc .

1 895

LON bON

VV fX IQ I),IJ I Dfl l

'

f IE I)

6 , FA RRD KHX D J A V E NUE LE C .

THE AUTHOR’S PREFACE .

PHOTO-LITHOGRA PHY, with i ts many b ran ches an d its ext ended

app licat ion , wh en u sed direct and al so as han dm aid for t h e

l ithograph er and prin ter from ston e,i s

, w ith the exception of

ph ototypy an d au totypy, in deed that process for the preparation

o f letterp ress plates which has don e the m ost t owards makin g

p hotography u sefu l for th e graphic arts,in the artisti c sen se as

w el l as from the practical po in t of V iew . A n d in the n ear fu tu re

it w i l l be a great acqu isit ion when . 1t i s on ce gen eral ly recogn ized

that colou r p lates c an be prepared by photographic m ean s w i thou t

any con siderable am oun t of m an u al or arti s t ic help . It i s the

m ore to be w on dered at that photo-l i thography has n o t yet fou n d

t hat ex ten sion and gen eral u se which i t in so‘ high a degr e e

deserves .

I have w ritten th i s b ook,im pressed w ith the u rgen cy of ‘

stim u latin g the propagation of this u sefu l process . I n w ritin g I:

have been carefu l to avoi d all ' those details wh ich are for the

p ractical worker of m in or in terest— th e description of th e

h i storical evolu tion , etc . so in stru ctive as these m u st certain ly be-so that I have abstain ed from m any com p l icated and “It

”

.

i n tel l igible form u lae . I le ave th is w il l ingly to a m ore ready

w ri ter . Starting rather from the st an dpoin t of speak in g as a

pract ical w 01 ke r t o p 1 ac t ic al m e n, I have recorded all t h e

e xperien ce which I have gain ed in the cou rse of m any years .

Shou ld it occu r to m e in the fu tu re that it was m y task t o h ave

treated all photo- l ithographic processes , w i th al l their ram ifica

tion s,in th e m ost com plete m an n er, I have sti ll th e con sciou sn ess

o f having described as com pletely as possible the practical

processes

,and think th at I have thu s been u sefu l to m any workers

,

B

2 PR E FA C E .

an d I dare say w ith absolu te certain ty that on ly tested and tried

form u lae have been n oticed in th is book .

W ith the earn est w ish that thi s book m ay be received wi th a

fraction of the goodwill wi th which I have worked at the writ ingof th e same, I presen t i t to the techn ical world.

GE ORG FRITZ .

V ien n a.

On receiving th is work for review I was greatly struck w ith th e

thorou gh ly practical m an n er in wh ich i t was written, an d thought

than an E ngl ish tran slation might be acceptab le t o the large an d

ever in creasing class of photo -m echan ical workers wh o m ight n o t

o therw ise have the opportu n ity of reading i t in the origin al . I

h ave kept to the au thor’s text as close as i s con sisten t w ith th e

idiom atic con stru ction of G erm an .

I am i n debted to Messrs . Hazel l ,Watson an d V in ey for perm i s

sion t o u n dertake the task of tran slating the work for an other firm

o f pu bl ishers , an d I hope the tran slation m ay prove as acceptab le

an d u sefu l t o the readers as it has been p leasu rable to m e to

do it .

E . J. WALL .

Creed Lan e,Lon don ,

E C .

INTROD UCTION.

I .—The theory of p rin ting from ston e . H e Wh o w ou ld stu dy or

p ractise pho to-l i thography m u s t first becom e acqu ain t ed w i th thefun dam en tal prin cip les o n which l ithography res t s . I find it

therefore n ece ssary t o first g ive in con cise form a sm al l treat i seo n the theory of t his process as w ell as o n t h e m ost im portan tm aterial s which are n ecessary in the practice of the sam e .

Th e theoretical prin ciple of l ithography is pu rely chem ical, an d

i s based prin cipal ly on the repu l sion of water an d o ther su b

stan ces by fatty bodies,an d the alterat ion of these greasy b odies

b y acids . As t h e s upport for thi s chem ical opposi tion a s ton e or~z in e plate i s u sed , which are su fficien tly porou s to al l ow grease

,

water,acid

,an d certain resin ou s sol ution s t o pen etrate t o a certain

degree .

T h e fatty substan ces wh ich are tran sferred t o th e ston e b yw ritin g,

draw in g,or t ran sfer, are au tographic ink

,l ithographic

ink,an d chalk

,the se -called tran sfer an d pho to-l itho graph ic

“colou rs . T h ere are also other substan ces,

. wh ic l1 are u sede special ly in photo-l ithography

,which do n o t eviden tly pen e trate

the st on e an d which can n ot be con sidered as greasy substan ces,

b u t wh ich ,as we shal l see later o n , have e xactly t h e sam e . action .

Th e above-men tion ed fatty substan ces actu al ly pen etrate theporou s st on e and m ake it in places su itable to take m ore prin t ingink . By the se -cal led e tching— dilu te n i tric acid m ixed w ith

gum water— two effects are produ ced . On the on e han d thefat ty bodies are altered in chem ical com posi tion , being decom posedin to , the fatty acids which com bin e in tim ately w ith the mat erialof th e ston e— calcium carbon ate . On the other han d ,

th e su rfaceo f th e ston e n o t covered w i th the fatty substan ces i s chem ical lyc h an ged ,

s in ce the carbon at e of l im e is con verted in to n i trate ,which has n ow the property of keeping m oderately dam p whenm oi sten ed w i th w at e r

,an d t hu s repell ing grease . If su ch a

t ran sfer of greasy bodies o n t o the ston e is al lowed to act for som eh ours, an d the fatty su b stan ces are rem oved w ith tu rpen t in e , i tW il l be seen that these places have a l ighter colou r than the oth erparts of t h e su rface of the ston e

,an d if the st on e be rol led u p

wvith a leather roller,charged w ith a greasy ink , af ter th e ston e

4. ru e ro -m rn o om rm’

.

h as been dam ped, on ly th ese places w il l take t h e greasy ink . Bym ean s o f a li tho s t eam or h and press prin ts c an t hen b e p reparedfrom this .

I t i s frequ en t ly n ecessary to m ake correction s or addi tion s to th edrawing o n the s ton e ; if t h e ston e h as been already etch ed som e

m ean s m u st be u sed which will rem ove th e ac tion of the e tching, or

e lse the s tone w il l n o t take t h e greasy m atter, or at least n o t so1 e adily as i s desirable . V ery w eak ace t i c acid

,abou t 1 -2 per cen t .

w ill do this . If t h e stone i s flowed over W 1th t hi s dil u t e aceticacid or dilu te tabl e vinegar, t he action of t he s tronger n i tri c acid’

a nd the g um i s s top ped , and the su rface of th e s t on e will againtak e fat ty m atter .

Before th e pen etration of th e grease th e s ton e is prepared by."

pol ishing w ith a concen trated solu t ion of oxali c acid . Oxal ic acid"pou red o n t o th e

“

ston e wou ld exert an e tching action , b u t m ake th es tone t e a certain degree capable of t ak ing the ink . If this l iqu id 1a

1 u bb ed o n the s to n e w it h a cloth or l in en pad w ith moderat e :pre ssure , the ston e receives a high pol ish— especial ly th e hardkinds—

"

and 1n th is con di t ion the st on e t akes t h e ink w ell ; l ike any "

ilat ' object, b u t wi l l n o t retain i t . If a t ran sfer 1s made on to su cha s tone

,an d the sam e etch ed , the 1m age w i l l com pletely disapp

t he firs t tim e the rol ler passes over i t . T h is’

p olish c an“ be

moved w ith -1 or 2 p e r cen t . ace t i c acid,and th e s to n e th en has its

p rim itive qu al ities . Th is m ethod is u sed to reverse the im age,

W hich w ill be described later o n .

2 .

—Litho ston e i s den se l im eston e of the m ou n tain l im eston e

g roup , an d i s found in the T ertiary depos its at a depth o f .

t wo to three m e tres . Its con stitu en ts are l im e,clay

, and siliciou s ,

ear ths,com bin ed w i th carbon ic acid, b u t l im e is in th e p re p on de rn

an ce ; i t on ly con tain s a very sm al l proportion of si li ca . I n th e

s trong er acids l itho ston e dissol ves com pletely. Th e varieties ofiv 01 y tin e s t alactitic chalk of tolerable hardn ess

,w ith flat shell l ike

f 1 ac tu re,w ithou t ru st spots , glassy crystal s or im pu rities , an d th o se v

wit ‘ 1 very even grain , are the m ost u sefu l for photo lith og1 ap hy .

Marb le , which con sists of p u re chalk,can n ot be u sed for l ith o m

g raphy becau se , o n accoun t of its greater den sity,the greasy m atter

can not pen etrate so’

deeply, and therefore su ch ston es wou ld give'

o n ly a few pu l l s .

-.T l1e comm ercial l itho ston es are of difi e ren t colou rs , from

w hit i sh yel low to green ish shin ing grey . Th e latter has a fin er an d

m ore ’

e 1'

fe n grain,and i s con siderab ly harder than the other k in d .

These two k in ds are b riefly design ated in th e trade as y el l ow _

an d “ bl u e ”

an d the brigh ter kinds are,as a ru le, softer an d

c h eaper t han th e darker .

Th e fau lts which the ston es sometim es show differ con siderably,and these produce certain in con ven ien ces in con tin u ou s w ork.

Many ston es have dark and l ight spots,an d as these spots have , as .

a ru le,differen t den sities

,the etching solu tion can n ot exert t h e :

5G t . _ c

«s ame action over th e whole of th e stone , an d con sequ en tly in fin e

d raw in gs , au t otypes , etc ., there are formed bright an d dark spo ts.

T his al so oc cu rs w ith calcareo u s, speckled , an d m arbly ston es . Th e

v ery bright s tones have less dehsity , and th erefore su ck up t h e

d am ping solu tion very qu ickly, an d beg in w ith repeat ed prin t ing tob ecom e tin ted . Ston e s w i th calcar ,eou s ru sty or other vein s sp lite asily,

especial ly iii th e large sizes . Lim e spots or l im e v e in s ,w hich are e asily recogn ized by their brighter colour

,t ake 1n grain

i ng a very u n equ al grain . T h e draw ing i s darker o n these p laces,

s in ce the grain i s greater according to the softn ess of t h e ston e.

S uch ston es are. u n su i table for th ese photo l ithographic pro cessesin w hich grain ing i s u sed

,su ch as t h e processes of Orel l an d

F iissli and Bart iis . Th e se cal led glass vein s an d glass spot s arec ry s tallizat io n s con si st ing of s il icon ,

an d are harder t han t h e o the1

p arts of the ston e . On t hese p laces t h e fat ty inks do n o t p e n e t 1 at e

d eep en ough,and th e drawing doe s n o t adhere wel l

,and c an be

e as i ly rem oved by the rol lers .

T h e h ard ston es receiv e a m u ch fin er su rface than th e softwh en p ol ished w ith pum ice ston e ; they also 1 e p 1

1

o du c e everypoin t

,l in e , and detai l of th e di aw 1n o 1 m u ch m ore del icat ely ,

ifin e r, and sharper ; an d, last ly,they

zD

h ave th e advan tage thatthey etch m u ch m ore even ly

,and re -etchin g i s easy if m oderat e

c are be taken .

Fo r the fin er ph oto l i thographic wo rk if qu al i ty and con tin u ou sw ork in g i s desired

,on ly th e good blu e ” s ton es shou ld be u sed ;

fo r cheap er line drawings ye llow stone s free from fau lts m ay beu sed .

3 .—

.The zin c p lates are n ow c om m g i n to p re tty g0"e n e ral u se l n

1

s tead of ston es, especial ly i n large establ ishm en t s . Al though theirt re atm e n t b e fore and du ring prin tin g i s essen tial ly d ifferen t tot hat of the ston es , yet so far as regards -th is m ethod of prin tingt hey com e very n early equ al t o ston es . At first sm oo th pol ishedz in c plates w ere u sed

,b u t in con sequ en ce of som e d1fi1 cu l ty

m u sin g them,an d th e great care n ecessary in choosin g t hen

,

t hey h ave been alm ost rep laced by the prepared or ox idized

p lat es .

Z in cograph i c processes differ essen tially m the preparation oft h e plates . I n the o n e , the p late i s gi ven a coat ing which has a

s im ilar com position to a lith e st on e ; in t h e other, the plate i s_

ro ughen ed and given a fin e grain by a m ech an i cal m e thod ,su ch as

t h e san db last, in order that it may be then ox idized by a chem ical

p rocess , w ith acids or alkal ies . Al l these pro cesses are m ore orl es s advan t ageou s . Th e zin c plates cost abou t o n e ten th to o n e

t wen tieth of t h e cost o f_

t h e ston es , an d th i s m ay w el l be su fficien t

groun ds for th e pro pr1e t o 1 s of large establishm en ts being in tei estedi n z l n e plates , as t h e s ton es are rather costly .

E xce l l en t zin c plates , coated w ith a film or merely ox idized can

b e precured comm ercially in G erm any and Au s tria . Fo r th ose

t“)

.1 PHoTo -e n oa Pn Y .

ivh o w ish to prepare their own plates th e fol low ing tes ted form u lae

are give n .

A z1n c plate from 1 to 1 5 m m . thick i s roughen ed by m ean s ofth e sandblast t i l l it has a fin e

,even grain an d appears sm oo th

,b u t

c lean . T h e fol low ing solu t ion i s preparedCon cen trated sol ution of 1

11 111 111

Phosphoric acidW ater

A lum 10 partsG al l ic acid 1 5

N i tric acid 2

W ater 30n

T h e roughened plate i s fi rst flowed over w ith water , an d im m e r

d iat e ly aft e rwa1 ds , w i th o n e of the above sol u tion s,in th e sam e

w ay as a p late , is covered w ith a developer . Th e plate is ox idizedby t h is , an d there I S form ed o n the surface a white precipitate . I t

is then w ash ed thoroughly u nde 1 a rose tap an d dried, an d t h e

p late m ay be ei ther coated w i th a l igh t sen si tive substan ce forprin t ing or a tran sfer be m ade on to i t .

A fter t h e developm en t or th e t ran sfer th e p late is gummed and.

t hen etch ed w ith an etch ing solu tion c o n s ist ing of

G al lic acid 10 partsPhosphoric acid 2

G um sol u tion 10

W ater 30

th is being al lowed to act for 30 or 40 seconds .

F o r repeated prin ting o n e to two per cen t . of gal l ic acid is addedt o t h e dam ping water .

If the plate has been correctly treated the prin t 011 the ph oto

l i tho tran sfer w i l l fu rn ish thou sands of good im pression s , j u st l ikea ston e . Furth er details as to the prin t ing o n th e zin c p lat es

,o r

t h e tran sfer of the c h rom ate d gelat in e prin ts on to the sam e,w il l be fou n d in Chap ter I V .

41 .— The greasy drawing ma teria ls which are n ecessary for lith o

g i aph y are l itho tu sch , au tographic ink , an d fatty chalk .

Th e two first are u sed i n t h e l iq u id state , the ch alk, however, insolid form . Th e ink can be obtain ed i n a l i qu id form and the twoo thers in sol id state . Al l three m aterials con sist p1 in c ip ally of

soap,tal low,

wax, resm ,

an d soot . Soap and tall ow gl ve the n e c e s~sary grease , wax an d resin give hardn ess an d con sis ten cy,

and sootth e colou r. Th e proportion of grease in the draw ing m aterials.

m u st b e so great that even th e fin est l in es or poin ts ofo

a draw ingc an be w el l tran sferred to the ston e , so that they m ay n o t b e

a ttacked by the proper etching sol u tion,and do n o t break away

h orn the ston e by con t in u ou s prin ting . As m u ch black as possiblein t h e draw ing m aterial s is p leasan t for th e d1 au crh tsm an bu t is.

n o t actual ly n ecessary for this part icu lar pu rpose .

I NTROD UCT I ON .

The tu sch m u st dissolve w el l in di stil led wat er an d flow fin e

an d clean from th e p e n . It shou ld be t o le rab ly brit t le, and t h e

frac tu red s urfac es sh ould be sh iny. The ph ot o-lithograph er w i llfrequ en tly req u ire th e l ithographi c tu sch for add i t ion s or forcorrec tion s . The best i s th e so - cal led Lem e rc ie r

’s t u sch

, wh ichis u sed in n early al l works . It con si sts o f

Y ell ow wax 2 partsMu t ton tall ow 2

Marseilles soap G

Shellac 3

Lam p black 1 -2

Th ese ingredi en ts shou ld be m el ted toge th er by b oil ing.

The au tographic ink i s,as a ru l e, u sed for drawing or writin g

o n paper,an d t h e resu l t i s th en tran sferred t o t h e s t on e . In st ead

o f t his , an y l itho tu sch c an be u sed,b u t for som e work th e au t o

graphic ink i s m ore advan tageou s . Th is ink m u st be t hin,run

eas ily,b u t n o t patch ily ,

from th e p e n ,and m u st keep for a l on g

t im e equ al in q ual ity and action . I t i s very advan tageou s thatspecially-prepared paper i s n o t requ i red, sin c e thi s always m akesthe work m ore difficu l t ; firm ,

h ard wri t in g-paper is q u it egood en ough for th i s w ork . Th e com m erc ial inks gen eral lypossess th ese good q ual i ties , an d if m u ch i s n o t req u ired o n e w il lhardly c are to prepare it on eself. A good successfu l au tographicink wh ich draw s in brown m ay be obtain ed from t h e followingform u la

Marseilles soap 10 p artsTall ow 10

12

Y ellow wax 12

Mastic 5A sphal t 4

V in e soot 3D istilled water 125

Origin al s prepared w ith th i s ink tran sfer as wel l imm ediatelyas after several m on th s

,and ordin ary w el l-sized

'

writing paper c anbe u sed fo r drawing or wri ting o n .

Li thographic chalk i s on ly prepared in th e sol id form fo r drawing o n paper direct or on s ton e . A ccording to t h e n atu re of th ework ,

it i s h arder or softer, fatter or lean er. The hard kin ds,

wh ich are al so u su al ly lean er, con tain m ore resin and less fat ;t h e soft, on th e con trary

,m ore grease .

Fat ty chalk i s com posed o f

Wax

Marseilles soapTal lowShellacLam p b lack

8 PHOTO-L imn o c nxru Y.

L ean ch alk i s com posed ofW

'

ax 12 parts .

Marseilles soap 8

Tallow 2

Shellac 10

Lam ph laek 4:

Fo r lith og1 aph ic “ 01 k a greasy ink 1 3 requ ired in con trad ist in ction t o 01 dinary print ing ink, wh ich con sis t s of l in seed o il

and lam pblack, which wou ld be cal led “ lean .

”

For inking-u p aphoto l it hographic ch rom at e d gelat i ne p xin t su c h an ink can n o t beu sed . I n order t o obtain a good resu l t in tra 11sfe 1 ring, t his inkm u st con tain grease, soap , an dA ny good tran sfer ink c an be u sed for a developing ink , as th is

is appl ied w ith a rol ler. It u sually con si sts of eq ual part s oftall ow

,wax,

soap,som e resin

,an d as m u ch l itho ink as all th e

o ther ingredien t s p u t t oge ther.

That p 1 e pa1 e d by C .

C

,Kam pm ann Tech n i cal In stru ctor in th e

K .K . [JCh I '-u nd V ersu ch san s talt at V ien n a,con tain s

,besides the

above -n am ed in gredien ts,asph al t and gum e lcm i, and works wel l

in prac t ic e.

Thin developing inks , wh ich are distributed w ith a broad bru shor a pad, c an be prepared by d ilu t ing good tran sfer in k w ithequ al q u an tities of wax, ben zin e, and t u rpen t in e .

A good developing ink m u st h ave the followin g proper ti esWhen spread u pon th e prin t m u st give a clean

,sharp , su ffic ien t ly

den se im pression, which c an be eas ily tran sfe m e d to t h e p lat e or

ston e ; o n the other h an d,t h e draw ing ough t n o t to sp 1 ead . Th e

tran sfer sh ou ld possess su ch resis tan ce that,w i th ou t roll ing u p ,

i t shou ld resi st a sl ight etching5 .

— The behaviour of a sp halt on ston e o r zin c . W hen a ston e or

plat e is coated w ith asphalt solu tion and exposed u nd er a n egative,

and t hen w ashed w i th turpen t in e,the exposed parts rem ain

in solu ble , and in this way ph oto -l ith ographs c an be prepared.

Th e asphal t h ere t akes th e plac e of the fatty ink,an d is

,after

p rin t in g ,so firm an d h ard that

'

w i th ou t any rol ling or inking u p itc an b e etched w i th a weak, gum m y

,e tching solu tion ,

which givesa clean er

,sharp er drawing t han t h e other processes . The asphal t

an d other l ight sen sit ive resin s n o t on ly in t im ately com bin e w i ththe ston e or plate , b u t ch em ic al ly alter t h e su rfac e of th e ston e

,

an d possibly in a m ore advan t ageou s way than t h e g i e asy in ks .

When a properly exposed draw ing o n s ton e is,im m ediately after

prin tin g an d developm en t , treat ed for a l on g t im e w it h 1 e c t ifie d

or N c u s tadt t urpen t in e , i t i s com pletely rem oved f1 om t h e ston e ,and it w ill be found that th e drawing appears of a somewhatl ighter colour t han t h e rest of the surfac e of the s ton e . If this 18

110W inked up w i th a roller, these places take u p t h e ink withou t

having p reviou sly com e in to con tac t with. mouse . N um erou s e xp e ri

m en ts wh ich I have m ade on variou s l in es go t o show that the

INTROD UCTI ON . 9

‘

c h em ical th eory o f l ith ograph y has found an im portan t en largeJm c n t w i th th c ‘

u se of asphalt .The following are prin cipal con clu sion s to be drawn from m y

e x perim en t s

(a .) The e xpose d asph al t , wh e th er th i s exposu re i s m ade byprin t ing or wh e ther a draw ing is firs t m ade an d then exposedt o the ligh t

,adheres m ore firm ly to th e ston e or zin c plat e

t han if it was n o t exposed. A n asphal t drawing preparedin th e dark and inked u p does n o t adhere to th e s t on e

,an d t h i s

m ay b e explain ed in that t h e grease can n ot ac t t hrough th e

a sphalt fi lm . Insen s itive asph alt behaves in t h e sam e wayW i th c or1 e c t exposure u n der a cl ear n egat i ve of abou t 20 degrees

‘

V ogel , an d subsequ en t developm en t an d auxilia1 y e xp o s u i c fora bou t half to o n e h ou r, t h e d1 aw ing adl1e1 e s firm ly t o t h e s ton e . Ift h e 1m age is to be w ashed off

,t h e t u rpen t in e mu s t ac t for fiv e t o t e n

m inu tes o n the fi lm,til l t h e exposed asphal t has di s solved . If, aft er

w ash ing off, it i s inked u p , a ll th e places take the ink wel l,and

t h e im age appears clear and p lain . The im age c an on ly bed estroy ed by s trong acids or alkal ies

,wh ich ac t ual ly d issolve t h e

ston e i t sel f .

From this i t i s cl ear th at th e prin ts n eith er requ ire ink in g u pn or stren gthen in g in any other way , and m y experim en t s h av e

p rove d t hat incD

all c ases the prin ts are,by t his t reatm en t

,

c logged u p , an d n either gain as regards a longer run n or in w iths tan din g et chin g .

(b.) Sol u tion of asph alt, to wh ich oi l h as n o t been added,beh aves

a s described above ; if, h owever, o il i s added to it,i t act s st il l

better as regards t h e keepin g of t h e drawin g, an d th e prin t s n eed'

n o subsequ en t exposure . Too large an addition of o il h as t h e

di sadvan tage that , in developin gzD

w ith tu rpen t in e,t h e asphal t

d i ssolves too qu ickly. The im ages w ash o ff an d o n e 1111 1 dly hastim e to exam in e . Th e exposed asphalt

,t o whi c h oi l has been

a dded, al so d issolves very readily. Fo r t h e preparation of colour

p lat es th i s poin t i s of som e im portan ce .

6 .— The et chin g and preparin g solu tion s are th e se solu tion s

w h ich m ake t h e s t one su itable or u n s u i table for t akin g the g 1 ease0 1 water . G en eral ly these are acids and gum a1 abic

,e ith e 1 u sed

a lon e or together.

Of the acids t he m ost im portan t is n itric acid, th e pu rpose o fw hich 1 8 t o c on v e i t the su rface of th e ston e in to a n itrat e

,so that

t h e grease cann ot p e 11e t1 at e Th is ac id acts even when dil u tedv e l y en erget ic al ly on t h e s ton e , and produ ces a fin e grain .

Hydi o ch lo ric acid exerts a less en erget ic ac t ion ; it l eave s t h eston e sm oo ther an d does n o t attack it so even ly a s 1iit 1 ic ac id

, b uth as t h e sam e resu l t fin ally .

Su lp hu ric acid ought no t tobe u sed for etch ing ston e . I t form sc alcium su lphate on t h e s u rface of th e s ton e , an d this sep a1 at e sfrom th e s ton e in prin ting an d spoils t h e p u ll s .

IO rn oro -u rn e c RA PHY .

P hosp hor zir acid m ay be u sed for etch ing as w el l as for preparingt h e s ton e ; it exerts a very fain t et ch ing action an d i s s eldomu sed for thi s pu rpose , b u t prin c ipal ly for m ak ing correction s .

A ce tic acid plays a very im portan t part in l ithograph y. l t

possesses the property,even in very dil u te condi tion

,of s t oppi ng

t h e ac t ion of t h e gum and oxali c ac id ,a nd

,indeed

,even that of

t h e s tronger n i tric , su lph uric , and h ydroch lori c ac ids . It finds,

therefore , con siderab le use in n egat ive p rin t ing,in m ak ing

c >rre c tio ns , e tc . I t con vert s th e ston e in to i ts orig inal condi t ionan d m akes it su i tab le again for t ak ing in k .

Citric acid fu lfils t h e sam e pu rpose, b u t is

,h owever

,m u ch

h igher in price .

Oxa lic a cid i s n o t u sed for etch ing, b u t on ly for preparation o f

the s ton e . By rubbing t h e s ton e w ith a sol u t ion of oxal ic acidw ith a p ad of c loth i t t akes a m i rror-like surface or pol i sh

,in to

wh ich t h e fat ty ink can n ot pen et rate . I t i s u sed for preparingth e s ton e for l ithogravure

,n egative drawing

,and n egative

tran sfer,etc .

Tin c ture of ga lls, or in stead of th 1s wh at i s sim pler, gall ic acid ,

i s u sed 1n l ithography . It con tain s plen ty of tan n in, an d i s o n e o f

th e m ost efficac iou s m ean s of preven ting th e com binat ion o f th e

ston e or / in c plat e w it h fatty substan ces .

Gu m, arabio or som e other vegetable gum i s indispen sab le forl itho an d zin c ography . A 10 per cen t . sol u t ion of gum i s gen eral lyu sed . I t pen etrat es all the pores of the ston e an d th e p late , an dgives the sam e a thin b u t very firm film

, and preven t s the inkt ak ing o n t hese places . If i t has bec om e s l igh t ly acid i t acts as aw eak

b

etcher,an d as an addition to n itric acid it m akes t h e sam e

of t hicker con sisten ce and m ore easily di stribu table . The actionof gum c an be rem oved w ith acetic or citric acid ; w ith wat er alon eth is can not be perfectly effected .

7 .— E tching th e ston e . There are two prin cipal etch ings , th e

simp le o rdin ary or first e tching, w hich obviou sly has the pu rpose of

givi ng the draw in g th e n ecessary stabil ity and prot ect in g th e

blank places from taking ink, an d the de ep or sharp e tching gives fo r

com bin at ion prin ti ng a still greater las t ing power, and for large1 u n s keeps the draw in g c lean an d sharp .

Th e ordin ary etch ing c h iefly cau ses th e fatty substan ces toassum e a n ew ch em ic al con dit ion ,

sin ce in com bin ation w ith thes ton e they form in soluble fatty salts of l im e

, which represen t th eprin ting su rfac es . It has

,h owever, al so th e p roperty of clean ing

t h e blank ston e su rfaces fi1 on1 any adh eren t grease , an d m akes t h eblank parts of th e ston e in capable of takin g ink

,also it m akes the

draw ing clearer and m ore preciseThe streng th of t h e first etching m ay differ, accordin g to th e

fol lowing c ircum stan c es

(a .) The ston e ; for hard ston es stan d a s tronger,an d soft ston es .

a weaker etching“

I NTROD IICT I ON . 1 I

(b . The p r1n ting im age ; fin e draw ings m u st at first be etch edw i th a weaker solu t ion ; coarser drawings , on the other h an d

,w il l

s tan d a fairly s trong et ch er .

(a.) The m at erial w ith wh i ch the prin t or draw ing h as been

p 11 1

e p a : e d1

,ve 1y fat ty devel oping inks an d asp h al t s t and wel l even

w i th s trong et ch ing , w h e i e as w ith lean or h ard inks on ly a weaketching shou ld be u sed .

A n e tch ing sol u t ion wh ich i s at th e l im it of strength , b u t stil lsu i table for a hard ston e or a very coarse draw ing ,

’

wou ldirretri evab ly 1

1

11 1 11 a very fin e draw ing o n a soft ston e .

Com m ercial ac ids differ con s iderably in st rength, and it is , th ere

fore,be t t er t o u se a hydrom eter than a m easure It is also

a lways m ore sat i sfac tory n o t to u se the acid by itself, b u t in c on

j un ct ion w ith gum . A sol u t ion of gum of eight to t e n degreesstrength i s dil u ted with n i tric ac id t il l it m easures 10 to 12

degrees on t h e h ydro .m eter Th i s solu tion m ay be safely u sed forevery case

,an d i t i s on ly n e c e ssai y t o allow i t to act longer for

coarser draw ings ; i t sh ou ld be even ly di s tribu t ed over th e su rfaceof th e ston e w i th a clean soft p ad . I n v e i y h o t w eather it actsm ore en ergetically , an d then i t shou ld be u sed weaker for fin e

work . I n any c ase it i s advi sable to let t h e ston e or plate stan dfor som e hou rs before etchin g

,so th at the ink m ay t horou ghly

com bin e . The etch ing of zin c plates will be m ore fu lly desc ribedlater o n ; in oth er respects the t reatm en t i s the sam e as for ston e .

D e ep- e tching p rocess. Th e idea of t hi s i s chiefly t o in crease

t h e prin t i ng form an d t o m ake t h e ston e m ore resistan t in prin tin g .

I n working th is the prin cipal th ing i s t o su ffic i en t ly protect t h edraw ing from th e ac tion of the strong acid . Th i s is gen eral lydon e by du sting w i th resin , wh ich has a low m e lting poin t .

Th ei c are two deep etching proc esses wh ich areo

ch ie fly u sed,

o n e in wh ich the resin i s m el ted w i th a Sp irit flam e,th e oth er in

wh ich the sam e t hin g i s don e by eth er vapou rThe p i e c edu r e in each case i s extrem ely sim pl e . I n th e se

called bu rn t etchin g process , w h ich h as been perfe c t e d by E berle,

of V ienn a , t h e already etc hed st on e ready for printin g i s rolled u pw ith a very st iff p 1 in t ing ink

,n o t tran sfer in k

,an d t hen th e

draw in g du sted w ith th e fin es t powdered resin . The ston e i s thengon e over w i th a cotton -wool p ad an d plen ty of t alc or Fren chchalk

,an d th en w el l du sted off w ith a broad cam e l’s h air bru sh in

order to rem ove all traces of resin from the blan k ston e . To m eltthe resin a spiri t lam p w i th a side flam e i s u sed . Th e flam e i s

p assed over the draw in g, and ought on ly to be al lowed to ac t

su fficien tly lon g to m ake the resin c om bin e w ith t h e ink,wh ich c an

be rec ogn izedm

by th e draw in g lookin g sh iny . I f it has beenm el t ed too lon g the sharpn ess of th e drawing is dam aged . A ft erthi s the etch in g m ay be at on ce proceededwi th ,

an d this i s effectedw i th a sol u tion of gum to which 8 t o 10 per cen t . by m easu re of4 4 per cen t . n i tric acid h as bee n added. Fm fin e drawings 4 t o

1 2 P HOTO-LI 1HOGRA PH Y.

6 p e i cen t . of ac id shou ld be u sed . I n u sing thi s a fairly strongeffervescen ce t akes place

,wh ich sh ou ld n o t frigh t en anyo n e

I n th e e ther or c old-m elt in g process exactly t h e sam e p 1 o c e duretakes place , on ly t h at in stead of m elt ing wi th an open flam e t h i si s e fi e c ted by e th er vapou r.For t h i s work a wooden st ick of abou t 2 m m . thick is laid on

two edge s of th e s ton e . On an oth er ru l er, wh ich sh ou ld be largee n e ugh

o

to cover th e wh ole of t h e ston e , and wh ich sh ou ld bec overed with flan n el or s tou t c lo th , ether is poured ; t h i s ru l er i sl aid o n th e o th ers , so th at it form s a right angle w ith t h em ,

and 1s

s lowly drawn over th e su rfac e of t h e s ton e . Th e e th er vapour

talls o n t o t h e su rface of th e ston e and d i s solves t h e res in w h icht hu s form s th e protect ive film for the deep et ch ing

, which i s don e

p rec isely as desc ribed above .A n o th er m el t ing process recom m en ded by Scam on i con sists in

pouring al c oh ol o n t h e s ton e and th en sett ing fire t o it .

9 .—D i17

"

e 7 e 77 tza tion of th e p 7 in t7’

ng p rocesses . Tech n ically w e

difie 1 e n t iate th e prin cipal prin t ing m eth ods in to th r1e e,ac c ording

t o t h e m e th od of produc t ion . Th e fi7 st and o ldest i s t h e typegraph ic o r le t t e rp 1 e ss prin t ing, wh ich i s fou nded o n th e prin c ipl et h at every lin e or every poin t wh ich ough t t o prin t m u st s tan d u po n th e plate, an d all th ose plac es wh ich m u s t appear wh ite in th eprin t m u st be su n ken in . The art ist i c effec t i s ob tained by t on esw h ic h are form ed of in dividu al lin es or poin t s , which are c losertogeth er or furth er apart , or else prin t fin er or deep er . I n prin ting a form e or plate , e t c .,

it m u st be ‘ ‘1n ade ready,

”

th at i s t o say,t h e p r ee ssure in prin t ing m u st be so arranged for each part of t h epictu re th at o n t h e light er places or finer pl ac es l ess pressu rem u st be exerted, wh il st 011 th e deeper ton es m ore pressu re sh ou ldfall

,according t o th eir gradat ion . Th is balan cing

, wh ich i st echn ically t erm ed “

m aking ready,” i s effected by cu t t in g o u t th e

delic at e an d bu ildin g u p th e stron g 011 dark parts on th e overlay .

With a proper overlay th e art ist ic effect of t h e pictu re c an bem uch in creased ; w ith a fau l ty overlay it c an be qu ite spoilt .

I n l et t erpress prin t in g th e artist ic elem en t lies in t h e m akingreadTypographic prin t s are di st ingu i shed by th e l in es , figu res

,etc .,

being som ewh at pressed in to t h e paper, an d sh ow rai sed u p on

t h e back, wh ich is t ech n ic ally t erm ed “ im pression .

” Wh en th is“ im pression ”

i s very plain,th at is to say wh en th e prin t in g h as

gon e pret ty dee ply in to th e paper. it i s advisable before 1 1 1

ep 1 0duc

t ion t o rem ove t h is by strong pressu re.The second m eth od of p 1 1n t 1n o 1 is exactly th e opposite of the

firs t , an d i s fou n ded o n t h e p i in c ip le of prin t in g from in taglio ;T h e l in es an d poin t s wh ich sh ou ld prin t are c u t m e ch an ic ally

'

(bye n graving or piercing) or ch em ically (by et c h ing) in t o th e st on e .

Th e et ch ed or en graved in tagl io plate r epre sen t s a n e gative ,'

or areversed wood-c u t

,on ly w ith t h e ditl e re n c e that th e lin es do n o t

m m onu em o s . 13

lay in th e sam e plan e . I n order to obtain an im pression the inki s pressed in to th e c u t -ou t parts , an d i s w iped o ff from t h e su rfac eo f th e plate . By s tronger or weaker w ipin g the prin t receives a .

stronger or weaker local ton e , which is o f great advan tage froman arti stic poin t of view, b u t which form s n o sm all obs t acle t o t h ereprodu ction .

Th e im pression i s represen ted in reli ef on the paper. A ccording t o t h e dep th of th e lin es t h ey t ake m ore or less ink ,

an d appeart h erefore raised u p in th e im pression accordin g t o th e am ou n t of

"

th eir depth in th e plat e . Reproduc t ion ph ot ograp hy has t o ,

reckon on this di sadvan tage , for with a side il lum in at ion th e

raised u p l in es cast shadows , and a correct n ega t ive does n o t

follow .

By th e th ird m eth od , lithograph y, of which w e h ave alreadySpoken ,

th e 1m p re ss 1o n lies gen erally flat o n th e paper like a drawing,

’

it a very s trong deep et ching was n o t u sed,in w h ich case it i s

al so sligh t ly rai sed .

o

I n prin ting from the graver 011 from st on e et ching a fain t reli ef I S gen erally n ot iceable

, which 1 8 n ever so high as:

w ith c opp e i p lat e prin ti ng and which i s n o im portan t obstacle t om aking a p h o togi aph ic n egative .

https://www.forgottenbooks.com/join

16 11 11oro -m rn o e 1111 11 11Y.

c hrom ium sal t ; and for the indirect transfer, th at process wh ich isfou n ded 011 t h e l igh t sen si t ive ch rom ium sal t in com b ina tion wi th

“

gelat in e, or briefly o n t h e ligh t sen sitiveness of ch rom at e d gelat in e .

A ll ot h er m ore or less com p l ic ated m eth ods have disappeared fromt echn ic al pract ice and have on ly t h e h onou r of b eing sc i en t ificallyin t erest ing and t h eoret ic ally c orrect

,b ut for variou s reason s are

n o t pract i c ally valuable .

I t is i ndeed obviou s t hat a discovery so im portant and u sefu lto on e of t h e prin c i pal departm e n t s of th e graphic art s as li t h ography is , and wh ich m ay b e called even m ore essen t ia lly capableof variat ion and m u l t iplicat ion ,

and pe rh aps in its“

way also m oreart ist ic , sh ould call forth an earn est m ovem en t o n beh alf of t h etech n ic al experts , prin cipally wi th th e endeavour for sim pler form sand ex t en sion of it s powers o f work . Th i s

,indeed

,h as n o t always

b een at tain ed ,an d th ese at t em p ts will therefore on ly be t aken i11 t01

c on sidera t ion in this book as m ay'

app e ar necessary,and a ll o th ers

will b e p asse d l o ver in si le nce .

,

Th e m et hods u sed by som e exp e rirn e n talis ts for direc t tran sfer,wh ich con sist in coat ing th e s ton e w i th a sol u t ion of gelat in e

,

album en , or gum m ade ligh t sen siti ve . w i th a ch rom ium sal tand after e xposure u nder a po si t ive or n egat ive

,obtain ing a

p rin t ing p lat e , were in execu t ion com plica ted and t roublesom e, b u t

in resu l t s fairly safe and sat i sfactory,so t h at th ey are n ow m ore

and m ore used in prac ticIron an d sil ver sal ts have been proved as n o t very su itable for

photo-li thography, and at th e presen t t im e for direct t ran sferasph alt i s m ost gen eral ly u sed

,and l at t erly also organ ic substan ces

rendered ligh t sen sit i ve by a ch rom ium sal t for indirect tran sferchrom ium sal ts in com bin at ion wi th gelat in e

,or ch rom at e d gelat in e .

A sp ha lt exposed to t h e ac tion”

of ligh t u n dergoes a ch em icalchange wh ich con si st s in its bec om in g less soluble in its origin alsolven ts . Th i s was kn own t o N ic e p h ore N iepce, o n e of th e discoverers of ph otography, wh ose endeavou rs t o produ ce im ages byth e act ion of ligh t were act u ally based u pon th is very property of

asph al t . He u sed for t h is pu rpose m e tal plates which were c onverted by. a species of e tching

‘

in to prin t ing plates .I n th e year 1852, t h e w ell -known Parisian lith ograph er

Lem erc ier, in partn ership w ith Le reb o urs,obtain ed a pat en t in

F ran ce for a process by wh ich they were in a posit ion t o obtainim ages on s ton e by th e exposu re of asph al t , an d th u s reprodu ce th esam e by prin t ing in th e ordin ary way . Th ey coated a lit h ograp h ics ton e w ith eth ereal solu t ion of asph al t , exposed it u n der a n egat iveand developed it with eth er the re remain ed beh in d th en th e part swhich h ad been rendered in solu ble by ligh t an d form ed a positi veasph al t im age on t h e s ton e, t h e ou tl in es of wh ich h ad t h e propertyo f taking u p greasy ink and with su it able preparat ion of giving an

im pression o n paper. Su ch a ston e was et c h ed in th e ordin aryway w ith acid and gum , and th en it was possible to m ake as m any

G E N E R AL norms on PHOTO-LI THOGRA PHY. 1 7

pu l l s from it as was de swe d 1n l i th o ink . W e h ave h ere a practicalphoto li th ograph ic asph al t p 1

1

o,

c e ss as it i s at th e presen t t im epract i sed w i th var1o u s m odificat ion s , an d which gave sat i sfact oryresu l t s .

O th er resin s besides asph alt m ay also be ren dered sen sitive toligh t

,an d it is w ell -kn own that th ey al so m ay b e ,u sed w ith as

good resu l t s as asph al t for ph o to-l ith ography.

Th at th e good quali ties of asphalt w ere even earlier rec ogn i zed1s proved b y t h e fact that N egre, before t h e di scovery of zin cetch i n g, exposed a copper-plate coated w it h asph alt solu t ion u n dera n egat ive

,wash ed o u t th e places n o t affec t ed by ligh t , elect ro

plat ed th ese blank places in a gold bath, th en c l ean ed t h e plat eand deep et c hed it w ith acid . H e obtain ed in t h is way an in taglioprin t i ng plat e sim il ar to an etching .

By u sing a posi t ive w ith this process a rel ief or typ ograph icplat e m ay be obtain ed , both of wh ic h processes are kn own as golde tch in g ,

”

an d w ere pract i sed i n the begin n in g of th e ’50 s in t h e

K . K . Hof—u n d S taat sdru ckerei .Th e asph alt wh ich i s u sed for photo-lithographic pu rposes m u st

possess certain qu al i t ies , of which th e m ost im porta n t i s as h igha l1gh t sen sit iven ess as possible .

1 W ith ordin ary asph alt su c c essw il l n o t be at tai n ed , sin c e it i s on ly sligh t ly sen sit ive t o ligh t ; t h ese -call ed Syrian asph al t i s th erefore gen eral ly u sed

,wh ich after

havin g been prepared i s dissolv ed in ch loroform an d then ben zolean d oi l of laven der are added .

Professor Hu sn ik prepares an asphal t from which all c on stit u en tn o t sen sit ive t o l igh t h ave been ex t rac t ed . Herr V alen t a produ c esh is su lphu ri zed asph alt . Both possess a far h igh er ligh t sen sit iven ess t h an e 1

1 1din a1 y Syrian asph alt, an d are speci ally su itable forph oto-l i thograph y .

T h e sec on d,an d con siderably m ore exten sively u sed m eth od fo r

photo l ith ograph y— a t ran sfer p i1

o c e ss— i s based o n t h e l igh t sen si

t i ve property of t h e chrom at e salt s in com bin ation w i tha

gelat in e,or album en ,

011

gum .

That th e bich rom ate salts possessed light sen sit ive properties,an d cou ld be u sed for ph ot o-l ith ograph y, Mu ngo Pon t on disc overedin 1839“ He prin t ed o n an ordin ary paper

,wh ich h ad been

ren dered se n sit i-ve ’to ligh t in a solu t ion of potassium bich rom at e ,draw in gs an d silh ou et tes

,an d obtain ed aft er fixin g

,wh ich w as

effec ted by m erely wash in g in pu re w at er, brown im ages on a wh it egrou n d .

Lat er Talbot fou n d that th e c h 1 om at e sal t s 1 n c om bin ati on w ithorgan ic subst an c es u n der t h e ac ti on of ligh t al t ered t h e p r

1

0p e 1 tyof t h e l at ter

,and part i c u larly t h at exposed ch rom at e d gelat in e

becam e in solu ble 1n h o t wat er . P oit evin u sed th i s disc overy forcarbon or pigm en t prin t ing

, an d h ad produ ced in 185 5 variou spict u res w it h t h is proc ess .

P oit evin di scovered fu rther that exposed ch rom at e d gelatin eC

18 PHOTO -LI THOG RA PH1Y. T1

wou ld n o t swel l up in cold water an d took u p greasy i nk, and

th erefore aft er exposure u nder a ph otograph ic n egat ive a p i ctu rec ou ld be ob tain ed exactly inversely correspondi n g t o th e t on es of 1

th e n egat ive and t h at th ese places affected by ligh t cou ld be inkedu p and prin ted from , or could b e t ran sferred t o a zin c or s ton eplate

,and from th i s pu ll s cou ld be prepared . By th i s di scovery

ph oto-li th ograph y and collotype were actually di scovered .

Le d o n by h is su c cess. Poi t evin u sed later,in st ead of gelatin e

album en and gum arabic , and prepared with th ese ph o to-l ith ograph ic prin t s

,wh ich we re

p

tran sfe rre d to s ton e .

If a solu t ion of gelatin e i s m i xed w‘

ith1 a solu t ion of bichrom ateof potash ,

and a sh eet of paper coated wi th th i s m i xt u re an d exposed , 011 if t h e pap er is firs t coated wi th gelatin e an d th en bath edin a solu t ion of bich rom at e of po tash , variou s ch em ical c h an gest ake place as th e resu l t of th e act ion of ligh t on the gelatin e film

,

w h ich we w ill n ow con sider .

A s h as already been m en t ion ed ,glu e or gelat i n e is in sol uble

,and

on ly swells u p i n cold water. I n warm water, however, th e gelat in o u s su bst an ce dissolves com pletely, an d se ts o n coolin g to a j elly .

If a su itable sh eet of paper i s coat ed w ith the w arm gelat in e sol ut ion

,eit h er by float ing or pou rin g it over it

,an d it be allowed t o se t ,

an d if th i s film i s n ow m ade light sen sit ive in a so lu t 1on of pe tassium bic h rom at e and dried in th e dark, we sh all hav e a photol ith ograph ic paper which , accordin g t o the greater or less q u an t 1tyof th e ch rom ium sal t u sed , h as a m ore 011 l ess in ten se yellow colour .

If th e paper thu s prepared i s exposed to l ight u nder a n egat ive,or

in an ot h er way if som e places before exposure are pro t ected byblack ink or s trips of paper, th e places affect ed by ligh t becom edark colou red and brown

, and at th e sam e t im e th ey h ave los ttheir power of swell ing u p in cold w at er. The whole su rface ofth e paper, that is t o say t h e exposed an d u n exposed film s beforebein g laid in wat er, are flat or in on e plan e ; if, however, th e prin tis l aid in cold wat er t h e exposed parts are n ot affected by t h ew ater

,t h at is t o say th ey have lost th e property of swelling an d

rem ain in t h eir origin al plan e . The u n exposed parts sw ell u p and

appear raised u p on t h e prin t,and thu s m ake the draw ing su nken

The exposed places h ave,however

,n ew received the property of

t akin g u p an d h olding greasy ink , whi lst the u n exposed h ave takenu p wat er an d repel greasy prin t ing in k .

If t h e paper be exposed u n der a n egative the draw ing appearssu nken in after developm en t w ith w at er th e other parts , whichm u st in prin t ing appear wh ite , are raised. u p ; by exposu re u n der aposit ive t h e reverse is th e case .If th ese prin ts are in any way , either by rolling u p or bru shin g

e ver, given a coating of greasy ink , th e ink on ly adh eres to th e exposed places an d a prin t in greasy ink is obtain ed, wh ich ,

like an yo th er greasy im pression , c an be tran sferred to a ston e or a m etal

SUBJE CTS WHI CH CA N BE R E PROD UC E D . 19

p l ate , which can be prin ted from direc t, or th e tran sfer m ay bem ade o n t o a m e tal plat e for relief e tch ing, that i s t o say for th epreparat ion of a typographic block .

I n Poi tevin’s process th e ston e i t self was coated w ith a l ight se ns i tivc c hr -om at e d film

, and exposed u nder a reversed n egat ive .

A fter developing and carefu l prel im in ary preparat ion of th e s ton eth e ink on ly adh eres t h en t o th e places affec ted by light .Th i s i s al so th e case if th e st on e is coat ed w ith light sen sit ive

a sph al t , an d t h e sam e prin ted on direct . A fter exposure th e part sn o t affected by light can be wash ed off w ith turpen t in e, ben zin e, orlin seed oil

,so that th e ston e is laid bare th e plac es

,t h e parts of

t h e draw ing affected by ligh t , h owever, are n o t dissolved . If th eston e i s n ew prepared w ith th e solu t ion of gum as has alreadybeen described, and then rolled u p w i th an in k roll er

,t h ese pl aces

wi l l t ake th e ii1k , an d by et chin g, e t c . t h e st on e m ay be so prepared th at the sam e m ay be prin ted from like any draw ing ore ngravm g.

By ph o to-l ith ograph y on ly l in e or grain ed draw in gs can be reprodu ced

,an d half-t on es , as i s possible w i th col lotype an d ph oto

gravu re,can n ot be ob tain ed .

N ow , w ith th e aid of au totypic t ran sfers an d th e asph al t proce sson grain ed ston es , w e have a perfect ly satisfactory m e th od of re

produ c in g in an excellen t m an n er half-ton e draw in gs by t h e aid ofphot o- l ith ograph y.

Ph oto-l ith ograph y in all l t s variou s bran ches of appl ication i sat the presen t tim e so perfect ed, an d rest s on so com paratively asim pl e prin ciple

,that a t ech n ic al prin t er, w ith very lit t le pract ice,

e xp e 1 i e n c e , an d ob se rvat ion of th e form u lae given,c an at tain l n very

sh o rt tim e absolu tely good resu lt s . A t th e sam e t im e it m u stbe said th at frequ en t ly very great difficu lties h ave t o be c o nten ded w ith especially as regards th e qu al ity of t h e m at erials an dn egat ives great care m u st be u sed .

2 . SUBJE CTS WH ICH CA N BE R E P“ROD UCE D BY PHOl O LITHOGRA PHY.

The n ext qu estion which arises is ,“ Wh at c an be rep rodu ced or

m u l tiplied by m ean s of ph ot o lith ography .9

The an swer is , A ccordin g to th e exist ing state of th e techn iqu eof photograph y an d th e perfect ion of th e t ran sfer process

,e very

t h in g .

”A ny l in e or wash drawing

,any oil pain t in g or oth er

plast ic obj ect,an y ph otograph of l ivin g c reat ures or l ifeless obj ects

—briefly,an y ph otograph c an

,u nder certain co ndit ion s

,be t ran s

ferred t o s ton e or a m etal plate,an d from t h is an y n u m ber of

im pression s in greasy ink be obtain ed . Before th e d iscoveryo f th e m eth od of breaking u p h alf-ton es in to poin t s or dots , on lyl in e draw ings cou ld be reprodu ced by photo- lithograph y . S in ce

,

h owever, it h as been possible t o break u p h alf-t on e in to l in e or

p oin ts or grain ,n othin g stan ds in t h e way of reprodu c in g by this

20 PHOTO-LIT HOG RA PH-

Y .

m ethod any kin d of origin al . This breaking u p of t h e“

half-tonein t o a regu lar or irregu lar grain c an be effec t ed by m ean s of acrossed lin e screen in m aking th e n egat ive

,as in au totypic

, or

hal f-t on e, block-m aking, or in dependen t ly of t h e m aki ng of t h enegat ive , as in t h e asph alt proc ess of Orell , F ussli and Cc .

,and in

Bartos’p roc ess and variou s oth er m eth ods .The u ndesirable half-t on e m u st , h owever, always be broken u p

in som e way in to th e requ isi te poin ts or lin es , as it i s o n e of th ech aracterist ics of l ith ograph y th at it i s on ly possible t o prin t fromd is t in c t figures o n th e stone . Li thography and let terpress prin ting produ ce im pression s of sharply -defi n ed lin es or poin ts

,each of

whic h m u st form a dis t in ct whol e . A n y t on e which i s light er orn o t absolu tely black m u st be form ed by lin es or poin ts s tandi ngin close proxim ity to on e an other. The t on al ity m u st be form ed bys tronger or weaker lin es or poin ts , by black an d wh ite spaces

, o r

by m ore or less close l in e and poin t pattern s . A n absolu tely closedt on e

,as in collo type or ph otogravure

,is n o t at tainable w ith

l ith ograph y,an d al th ough n um erou s exp erim en ts h ave n o t been

wan ting to reach th is e nd , th e sam e have hith erto been w ithou tsu c cess .Th e h alf-ton es are broken u p and separated in to solid prin tabl eoin t s zp

(a .) By t h e au totypic t ran sfer, which is effec ted by placing infron t of th e sen sit ive plat e when m aki ng the exposu re th e abovem en tion ed c rossed-l in e screen .

(b .) By th e so -called asphalt process,by m ean s of prelim in ary

grain ing of th e s ton e before coat ing w i th asph alt an d prin t in g .

(a.) By m ean s of th e produ c tion of a grain on ch rom ated

gelat in e .

(d .) By th e u se of a san d blast,wh ich is the chief poin t of

Bartos’process .

(e .) By tran sfer of a close grat ing or n etwork o n t o a pol ishedston e

, which form s th e basis of th e lith o- h el iogravu re process of

Gen eral-D irec tor Ch as . E cks tein,wh ich i s in cluded in photo

“

l it h ography .

A ll t h ese m ethods have for their pu rpose th e breaking u p of th eligh t

‘

t o n e s in t o regu lar or irregu lar b u t separate poin t s . Th ereare oth er m et h ods besides th ose m en tion ed above wh ich have th esam e pu rpose .

W e gen erally di st ingu i sh two kin ds of reprodu ct ion

(a .) Th ose from l in e draw ings,in wh ich a n egat ive i s m ade

wi th ou t t h e in t erposit ion of a cross-lin ed screen ,an d

'

for wh ich n o

oth er m ean s i s u sed for t h e produ ct ion of a grain ,and

(b .) Th ose from wash-drawin gs , pain tings , ph otograph s fromn at u re

,e tc .

,in wh ic h reprodu c t ion s th e h al f- ton es are ei th er

broken u p in t o lin es or poin t s by th e u se of t h e screen wh enm akin g t h e n egat ive

,or by any of t h e oth er above-m en tion ed

m ean s after m akin g th e n egat ive .

L IN E J 21C

(A .) L INE D RAWINGS.

By t h e first m ethod th e drawing m u st b e prepared accordin g t oc ertain form u la if a good n egat ive i s to be ob tain ed w h ich shalln o t requ ire m u ch after w ork an d di sadvan t ages for ph ot o- l it h ography. A

‘ poor original m ay cau se a partial or com plet e failu reo f t h e work

,o r at least cau s e m u ch cos t an d w as t e of t im e ;

t h erefore it appears advisable to p ay th e n ecessary at t en tion t o

t h e origin al w h i ch i s to be reprodu c ed .

Wh at a lin e drawing m u s t possess wh ich should be reprodu cedw ell by ph ot o-l ith ograph y in order to giv e a good t ran sfer o n t o

s t on e w e w i l l n ow poin t ou t .

Before al l th ings sh ou ld be n ot ed th at the paper m u st b e pu rewh i t e an d sm ooth , y e t n o t s tron gly reflec t ive an d n e t t o o w eak .

S m oot h wh i t e cards of m ediu m t h ickn ess are t h e best t o u se .

S ince all l in es of th e draw in g app ear in the im pression of t h esam e colou r , th ere is n o t on ly n o p urpose

,b u t it m ay even be very

di sadvan tageou s to th e reprodu c t ion when th e drau ght sm an,in

order t o in crease th e art i st ic effect of his w ork, or t o produ ce goodperspect ive , e t c .

,draws fin e lin es or oth er poin t s in a lighter

colour. Th e striving of t h e art is t for effect , perspec t ive , e t c .,so

far as th is i s attain ed by l ines or parts o f a ligh ter colou r,h as for

th i s process of reprodu ct ion n o advan tage,b u t

,indeed

,th e dis

advan t age th at by this t h e subseq u e n t m an ipu la tion s are ren deredm ore diffic u l t , th e whol e work will t u rn o u t m ore cos t ly an d fin allyless sat isfactory .

A l th ough from the presen t posit ion of photograph y drawm gs 11 1any desired colou r c an be reprodu c ed , yet it i s m ost advan tageou sif th e origin al s for ph oto-li thograph ic reprodu ction are drawn

w i th fin e black m at t ink o n sm ooth wh ite papers , and t h e prin cipalpoin t to w h ich att en t ion sh ou ld be direc t ed i s th at all l in es

,even

t h e fin est,sh ou ld be a good black ,

an d shou ld be kept of th e sam es tren gth of colou r as t h e o th er parts of th e draw ing . Th e thicklin es m u s t be qu ite filled u p l ike t h e shadow l in es of a stron glet t er . Sh ading m u s t be obtain ed by strong

,fin e run n ing lin es

qu it e sep arate from on e an oth er . I n t h is t h e singl e black l in esm u st n o t be too stron g, an d th e white spaces in b e tween m u st n o tbe t o o n arrow , or o th erwi se wh en redu ced in mm t h e whit ein t ers t ices w ill di sappear an d w il l fin al ly form a sol id ton e . Th e

lay in g on of a ton e or w ash i s n o t perm i ssible,as even a l ight ton e

w i l l appear in th e reprodu c t ion as a black spot . I tfis n o t per

m issible al so to draw 011 th e sam e origin al w i th inks of differentblackn ess or con si sten cy, an d even if a c olou red ink be us ed t h ewhole origin al m u st be prepared w i th on e c olou r (re d,dark bl u e,green

,or brown ), an d th at as in t en se as possib le . Wh en we s tart

from th e on ly t ru e s tan dpoin t , t h at every rep roduct ion sh ou ld bea reflex of th e origin al as t ru e as possible

,art i s tic effec t s have from

this poin t of v iew n o pu rpose, sin ce t h e prin ter in p r1n ting w i t h

22 PHOTO -L I THOG RA PHY .

o n e ink is n o t in a posit ion to give grey lin es as well as black, b ut

c an on ly give th e appearan ce of every th ing in o n e c olou r on ly . He is,

h ow ever,able t o give w i th th e s tronges t l in e t h e fines t w i th t h eir

own charact erist ic s , and c an ,t h erefore

,in this direc t ion at tain t h e

t on al ity of t h e origin al.t i s obviously, t h erefore , t h e art is t’s du ty t o draw in o n e colou r

,

and sin ce for ph otograph ic reprodu ct ion black is th e best,that is

t o say Ch in e se fink ,h e w ill do well to c om ple tely lay o n o n e side

all oth er art i st ic m aterial s or effec t s . A t th e sam e t im e it sh ou ldb e n ot ed th at origin al s drawn in an y o th er colou r c an be reproduc e d by ph ot o-l i th ography, b u t if th e draw ing is t o serve n o o th erpu rpose t h an for reprodu c t ion it i s best to p 1 epare it in black .

A fu rth er 1m po rtan t req u irem en t i s t h at t h e draw ing be sh arpl yan d clean ly worked ,

and since th e reproduc t ion of a ragged or

broken l in e can n ot niake a fu l l sm ooth beau t ifu lly ru n n in g lino

e,th ey

w il l appear in th e reprodu c tion in t h e sam e defect ive way , an d

th en req u ire at l eas t t ed iou s retou ch in g or m ake t h e prin t in g oft h e subj ec t act u ally im possible . If it i s n ecessary t o cross th elin es in t h e sh adows t h is m u st be don e w i th great c are . Th e

poin t s of crossing m u st be clean and sh arp,an d t h e ink m u st n o t

r un . Too close or t o o freq u en t crossin g of th e l in es sh ou ld beavoided

, an d w ou ld produce a b ad and differen t effec t in th e

1 e p rodu c t io n . Sm u dges or wrink les in t h e origin al appear in th ere produ ct ion m ore in ten se and m ore vigorou s

,an d t h erefore it

m u st n o t be forgo t ten to carefu lly avoid these, al so any t racingl in es m u s t be erased, w ith ou t , however dam agin g th e ink l in es orrubbin g u p of th e paper.Pen cil and chalk drawings , assu m ing th at they are clean ly

execu t ed, c an be w el l reprodu ced by photo l ithography, on ly t h ey

ough t n o t t o be sm u dged 01 inked . E rasu re m arks on pen cildrawings appear in t h e reprodu c tion as sm u dgy spot s .

D raw ings of arc h i tectu re for i llu strat ion or o th er pu rposes,

after con siderat ion of th ese rem arks , c an be wel l t 1 an sfe 11 1

1 e d w itho u t m u ch troubl e by ph ot o l ith ograph y o n t o ston e or zin c .

I n draw ings of m aps , plan s , e tc .,t h ere are s t ill som e ru l es to b e

observed besides th e ab ove . Bou n dary lin es or m oun tain rangesw i th fin e h atch ing, waterlin es for large rivers , seas or lakes , asw el l as t h e in trodu ct ion of figu res

,are better left o u t of th e

draw ing , an d c an be afterwards drawn on t h e s ton e ; t h ey w il lth en be c l ean er an d sh arper . If all th ese details

,h owever

,m u s t

be 1 11 1t 11o du c e d in to t h e origin al draw ing, they sh ou ld be exec u tedin a pal e blu e colou r

,wh ich w ill n o t appear in th e ordin ary

n egat ive .

For plan s w ith large let t ers it i s better n o t to draw th e l at t er,

whic h are frequ en t ly a lo t of t rouble , b u t t o em p loy t h e sim plerplan of gett in g t h e t it les

,writ ing

,l egends

,explan at ion s

,e t c .

,

pri n t ed by a book prin ter o n paper of t h e sam e c olou r as th eorigin al

,and s t ick th em o n t h e l at ter . Th e sam e m eth od m ay b e

https://www.forgottenbooks.com/join

24 PHOTO-L I THOGRA PH Y.

F o r thi s we u se a good firm drawing paper, which is sen sitized. in

t h e fol low ing m i xt ure 1

Sol u t ion A

P otassium fe rridcyan ide

Wat erSol u t ion B .

A m m on io-ci tra t e of iron 10

Water 100

W h en dis solved eac h sol u t ion i s fil tered and m 1xe d in t h e darkroom im m ediately before u se in eq u al parts . T h e solu t ion t h u sform ed is sen s it ive to light an d i s Spread o n a well -sized draw ingpaper as even ly as poss ible w i th a broad bru sh , equ al ized w i t h ad is trib u t ing bru sh , and t h en drie d in t h e dark room .

T h e coat ed side of t h e p ap er appears yellowish . I t i s thenprin t ed as u su al u n t i l t h e deepest part s look grey, as th e pri n t slook weaker a fter developing . T h e prin t s are developed byfloat ing t h em fac e downwards o n a dish of pu re w at er n o t t o o

cold,an d t h en wash ed t il l t h e drawing appears qu ite wh ite o n a

bl u e grou nd . T h e wash ing m u s t be thorough ly don e or else t h e

p rin t s t u rn blu e afterwards wh en exposed t o ligh t . These pri n t sc on tain a ll th e fines t de ta ils , even in t h e deepes t sh adows

,plain ly

vi sib le , and w il l n ow be t h e m os t perfect and m ost con ven ien t

p roofs fo r th e art ist . Th e t racing or drawing is n ow don e w ithgood black du ll su rface ink as already suggested . Wh en t h e

draw ing i s don e it i s al lowed t o dry th orough ly , w h ich w ill be infrom two t o t h ree hou rs . Th e fol lowing sol u t ion shou ld be

p repared

Oxalic acid 1 part10

wh ich sh ou ld be po ured i n t o a fl at dish an d t h e drawing allowedt o li e in it for abou t th irty m in u t es . I t i s th en again well wash edan d t h en im m ersed for fift een m in u tes in a bath of

Hydrochloric acid 1 partWa ter 20

T h e blu e colou r w i ll 110W h ave disappeared,an d th e ink draw in g

w i ll ap pear pu re black on th e wh it e paper. I t sh ou ld be n owh u ng u p and dried in t h e ordin ary way . This draw ing preparedin wash or l in e w i th in k n e w form s t h e origin al for a fu rt h er

p h o tograph ic n egat i ve , wh ic h i s m ade in th e correc t si ze of t h ereprodu c t ion w i th or w ith ou t th e in t erven t ion of t h e c rossedscreen ac c ordi ng t o th e ch aracter of th e drawing . W ith th e

n egat i ve t h u s ob tain ed a ph o to -l i th o o n s ton e 0 11 z in c . or a typograph ic c opper o r c ollo type p l ate, or a ph o tograph o n wood forxylography m ay be prepared .

T h e u se of t h is proc ess appears sp ecially im portan t for thosecases in which an ordinary ph o tograp h ic n egati ve is n o t su fficien t ,

D RAW ING S ON PR E PA R E D P A P E RS . 25

for exam ple where a prin t in g plat e c annot be prepared from th e

n egative . I t ough t al so t o be u sefu l w h en th e ligh t cou ld n o t bec on t rolled in m akin g t h e n eg

,ative an d t h u s in correc t effect s

appear I n th e reproduct i on wh ich often occ u rs in n egat i ves fromn at ure and w ith poli sh ed plast ic m etal obj ec t s . The en largem en t s from t h e origin al are t h en “

u sed becau se th e detail s c an bebetter seen ,

an d th e arti s t ic charac t er c an be m ore easily seen .

Th e fin en ess of th e draw ing m u s t obviou sly be in proport i on t oth e after reprodu ct ion ,

wh il e ton e s m ay be part ly or en t irely lost .

(a.) D RAWINGS ON PR E PA RE D PA PE RS.

For photo-11 t h o tran sfer w i thou t th e u se of a screen there aresom e com m ercial papers. t on ed, grain ,

n e t or pyram id g rain edpapers wh ich may be u sed w i th excellen t resu lts .

On these papers,ac c ording to t h eir p reparat ion ,

variou se xcell en t resu lt s c an b e ob tain ed, wh ich pos sess high c laIm s asil lu s trat ion s .

A sm ooth whi t e scraper board m ade by A ngerer an d G o sch l ofV ien n a, which h as a very even film of ch alk, and wh ich t akes th elin es clean and vigorou sly

,i s especially su it able for p e n and ink

Work . On t h i s paper plu cky draw ings like woodcu t s c an b e

e xecu t ed . Th e perfect wh i t es of t h e paper, com bin ed w i th thev igorou s beau tifu l black

,facilitate reprodu ction w ith excellent

resu l ts an d w ith ou t m u ch trouble .

1 A n ordin ary w rit ing p e n an d ordin ary Ch in ese ink are u sed fordrawin g. Th e ink gives su fficien t ly black an d m at t l in es .

Th e deepest parts are covered w ith ink , an d th e de sire d sh adingo r st 1pp l1ng p u t in w ith t h e tooth ed scraper or en gravin g t ool .The sh ading o ff of th e sh adow s m ay also be w o 1 l1 e d u p w ith t h etooth ed scraper

,an d thu s very del icat e sh adin g be ob tain ed .

Tw o m ore very u sefu l papers by th e sam e firm are kn own ass craper b o ardS ‘ w ith prin t ed l in es or poi n ts

,an d wh it e scraper

boards w i th sim ple 011 doub le l in es stam ped 011 t o it . Th ese

papers are also coated w i th a ch alk film

Fig. 1 .

W ith these papers th e prin ted l in es or dot s serve as half t o n esfor th e artist , an d

“

by scrapin g w ith sm ooth 011 t ooth ed scraper

kn i ves very m any effect s c an be obtain ed . Le ad pen cil, ch alk or

lith o ink c an be u sed for drawin g. For lay ing o n ordin ary in k

wi th a sm all addition of soap m ay be u sed,and n ew t on e effec t s

26 1

PHOTO-L I THOG RA PH Y .

m ay al so be produ ced w ith a half dry Chin ese ink bru sh , b ut foi1

an y draw ing for lin e reproduct ion wash ing w ith paler or darkerinks is excluded . By sc raping w ith th e sm ooth sc raper

,point s

are form ed in place of t h e lin es , wh ich by fu rth er scrapingdisappear en t irely i n t o white , by wh ich m ean s th e transit in t o t h ehigh est ligh t s i s effected . If a black su rface i s scraped w ith th esm ooth kn ife a lin e ton e i s produ c ed in t h e opposite direction tot h e prin ted on e . By t h e aid of t h e t oot h ed sc raper lin es in anydesired direc t ion c an be o b tain ed . Wh en th e p rm t e d t on e is on lydesired in part s in t h e pic tu re, t h e o th er parts c an be covered u pw ith wh it e paper. Th e paper i s on ly s t u ck down by t h e edgesw i t h m ou th glu e ; if it w ere s t u ck down all overw ith gum or starchit w ou ld be di st orted . On th e wh ite paper st uck o n , drawm g m aybe don e w i th th e “

p e n ,an d th u s n ew effects agai n be obtain ed

,as

th u s in a m an n er p e n an d wash drawin g are com bin ed .

T h e wh i t e scraper boards w i th ou t prin ted l in es or dots are

eith er im pressed w ith a single l in e or w i th lin es crossed at rightan g les .

On th i s paper p e n an d ink drawings com b in ed w ith grain edt on es m ay be don e . T h e ou t l in es and every th ing wh ich i s t o b etreated l ike a p e n drawing m ay be don e w i th a hard p e n or am arten bru sh . Brigh t ton es are so w orked w ith th e bru sh thatsm ooth su rfaces are n o t form ed, b u t do tted darker or ligh ter ton e sTh ose part s w h ich h ave been l aid o n qu ite black c an be brightenedup aft erwards w i th t h e sm ooth O1

1 t ooth ed scraper kn ife or th eneedle

,and t h u s m any gradat ion s ob tain ed. In st ead of t h e litho

writ ing ink pas tell or very black good lith o chalk m ay be u sed fordrawing . Obviou sly th is paper also ough t n o t t o be wash ed or

sm eared .

T h e pyram idal grain paper prepared by Sc h aufi e le n of Heilbron n i s al so very su itable for drawings for ph o to-l it h ograph ic reprodu ction . T h e paper i s coated wi th a ch alk film of blin dingwh iten ess, and i s s tam ped w ith a regu l ar grain of t ru n cat edpyram ids

,and i s produ ced in t h ree n um bers . G rain No . 1 c on

t ain s regu lar proj ection s per squ are cen tim etre ; grain N o . 2

con tain s and grain N o . 3 , 750 pyram ids .

Th i s paper is drawn o n w ith l ith o ch alk or black pastell c rayon s .Th e deepest sh adow s are,

laid O1I qu it e black, an d light effec t s arein t rodu ced w ith th e scraper 01

1 engravin g: n eedl e as w ith th e

above described papers . T h e sam e ru les apply to th e other partsof th e drawin g.

For drawing in gen eral or the u se of efi e c ts in draw ing it shou ldbe n oted that w ith all these papers the draw in g m ay be som ewhatoverdon e

,an d th i s i s n ecessary in order to obtain th e correspon d

ingvigorou s act ion in the reprodu ction . T h e prin tin g ink is, as a

ru l e,n ever su ch a deep black as t h e draw ing ink , n or i s th e paper

wh ich is u sed for prin ting ever so whit e as th e l in es of th e t on edpaper

. Th e con trasts wou ld, th erefore , in prin ting becom e t oo

R E PROD UCT I ON to r PRI NT S . 27

l ittl e, and flat u n sati sfactory pictu res w ou ld be obtain ed W ith

these drawings,therefore

,th e two opposites ,

“ black an d wh it e ,m ay be u sed t o th e extrem e, even if t h e d 1 awm o

1

1s n o t sati sfactoryto th e arti st i c e y e .

For m aki ng t h e draw ing re d paper ought n o t to be u sed, aswhen photograph ed re d appears dark . Th en blu e proof paper,or paper rubbed W i th lead pen c il , shou ld be u sed .

A draw ing for ph otographic rep rodu c t ion ough t n ever t o b e

roll ed,an d still less be folded

,if it i s to be sen t away it sh ou ld b e

packed flat .

( D .) R E PROD UCT ION OF PRINTS.

I t i s frequ en t ly requ ired t o m ake photo- li thographs of oldprin ts A s already m en t ion ed in the in t rodu ction , w e di stin gu ishth ree differen t m ethods of prin t ing , of which t h e two first , typography and lithography, are confin ed to the rendering of w elldefin ed l in es or poin ts

,wh il st Copper-plate prin t in g c an to a

certain exten t reprodu ce lin es and ton es . A S regards th e reprodu ct ion of th e first two

,so far as their fu ndam en tal ch aracter

goes,n o in s uperabl e difficu l t ie s presen t them selves , wh en th ey

correspond at l east t o th e gen eral requ iremen ts of a draw in g .

Sin ce a re p rodu c t 1on ,w i th exc ept ion s

,c an n ever be bett er

ob v10u sly w ith ou t very com plicat ed retouchin g— b u t always som ewh at in fer1011 to the original , th e appearan ce of the origin al w illalways be som e gu ide as to the qu ality of the reprodu ct ion thatc an be produ ced .

If,however

,prin ts are prepared specially for thi s pu rpose , th e

follow in g poin t s shou ld be observed .

1 . For prin ting a m att su rface a so -called pu re white chrom o

paper shou ld be u sed .

2 . The ink shou ld be black and of good body,the im press ion

clean an d sh arp , every lin e exact and n o t I n the least fu zzy .

The expert lith ographer wi ll easily prepare h is im pression .

A ssum ing th at he has a good origin al ston e , he w i ll m or e easilym ake good and correct prin t s from t h e engravin g from t h e chalk,p e n or other draw ing than th e typograph er . The lat t er has t ogi ve his im pressi on s th e correct fin i sh by m ean s of overlays ,w ithou t the correct m aking an d u se of which n o good p i ctu r ,

ewhether it be ch aracters or a drawin g

,can be obtain ed actu ally on

a typographic press . The reader i s referred to m y articl e inProfessor E der’s “ Jahrbu ch flir Ph o t ograph ic u n d R eprodu ct ion sv erfahren for 1891 , where I have t reat ed of th i s at l en gth . Prin tsprodu ced by the t liird m eth od

,copper-plate prin t in g, give far

greater difficu lties to the photo m echan ical worker . E very pu l lfrom th e en graved plat e— etchin g scraper '

drawin g an d ph otogravure exc epted— possesses a ton e on its surface

,wh ich i s , m ore

over,very u n equ al, and althou gh in creasing its art ist ic qu al i t ies ,

ofi e rs,however, con siderable difficu l t ies for reprodu ct ion . Th i s can

28 PHOTO-LI THOGRA PH Y.1

o n ly be avoided by v ery troublesom e retouching, which i s fre

q u en t ly preju dic ial t o th e beau ty of th e pictu re .

If pu ll s are Specially prepared for re produ ction t h e c opper-plateprin t er m u st very carefu lly polish h is plate and prin t w i th ou t at on e

,b u t st ill “

t h is m u st n o t be done so th at th e plate is t o o stron glypoli sh ed th at t h e dep th s lose t h e ir vigo ur ; th i s would give an

absolu t ely in correct pictu re as regards gradation of ton e .

E tc h ings c an ,as a ru l e, on ly be rep roduced w i th th e aid of a

c ross s grain ed sc reen , and t h e sam e ap p lies to ph o t ogravures,

al th ough t h e l at ter w il l seldom be req u ired .

A l l t on e or pa in t ed origin al s , su ch as wash or sep ia drawm gs,ph otograph s from n atu re , c ollo types , ph o togravures , wat er-coloursan d o il-colou rs c an on ly b e reprodu ced by ph oto-l ithograph y byth e interposi tion of a screen wh en m aking th e n egat ive

,or by a

proc ess in wh ich t h e breaking of t h e t on e is effec ted independen tlyof th e ph ot ographic n egative

,an d wh ich w ill be desc ribed later

I'V it h o ld ph otograph s which h ave faded it i s as wel l to in creaset h e ligh ts an d sh adows by pain ting.

( E ) S I ZE or THE R E PROD UCTION .

A qu estion frequ en tly asked i s , Ofwh at size sh ou ld a draw in gbe m ade in order t o ob tain a 1 good ph o tograph i c reprodu c tionT ln s q u

es tion can n ot be precisely an swered, for a g ood dealdepends u p on th e obj ect i t self, and o n th e kind of draw ingI t m ay b e gen eral ly said, h o ive ve r, part i cu l arly as regards p e n

an d ink drawings on sm ooth paper, that t h ey sh ou ld n ever b eler

,on ly very rarely of t h e sam e size th ey sh ou ld be drawn

o ne -t h ird or o n e -h alf l arger gen erally . T h e artis t c an execu t e fin e

d etails m ore easily and precisely o n a l arge draw ing t han o n a

sm al l -

o n e .

1

" The en larged reprodu ction gives any fau l t s or m i stakes which‘

m ayhappen t o be in th e draw in g in proportion at ely larger size

qu it e indepen den t of t h e fact that an en larged reprodu ct ion is

a lways som ewhat rou gh and ordin ary . R eprodu c tion in th e sam esiz e reprodu ces t h e fau l ts th e sam e si ze as t h ey exist in th e drawing ; t h e

redu ction ,however, al so redu ces th e fail ings of the

”

draw ing if it c ann ot also absolu tely rem edy t h e sam e . Th e re

u c e d c opy has always som ething fin er an d m ore d elic ate . Th e‘

degree of redu ct ion m u st be kept in m in d, an d the drawing bedon e w i th t h i s in view .

If a draw ing is execu t ed very fin ely an d fu l l of detail , an d,

besides th at, con tain s very sm all l in es of draw ing 011 t it les

,th ey do

n o t gain in'

re du c t io n ,b u t the opposite ; they lose, as m u ch t h a t in

th e drawin g appears pl ain and di stingu i sh able becom es by s tron gredu ction indist in ct and u n recogn i zable , or appears to the ey e as a

ton e .

S i s'

s. OF THE R E PROD UCT I ON .

Individu al cases , in which for specim en pu rposes or t o show h owfar redu ction c an

‘ go,m any tim es lin ear, five , si x, t o t e n t im es

,

can n ot be t aken in to con sideration ,al th ough th e effec t i s u sually

wel l at tain ed .

I t s hou ld al so be Observed that the draw in g m u st be con sideredn o t on ly as re g ards its size , b u t al so t h e s tren gth of th e l in es an dton es gen erally for redu ction ; t h is specially applies as regards th eton es . By redu cti on th e ton e gradat ion s are com pressed ,

t h e pictu re becom es poorer in ton es , a n d al th ough , t heoret ically c on

side re d ,l igh t an d sh adow

,th at is to say black an d wh i t e

,are

actu ally di s tribu t ed in th e sam e rat io as in th e origin al , y e t th ereduced im age app ears p roportion at ely dark er an d loses in art is tice ife c t

Great reduct i on s w il l,h owev er, be u sefu l wh en for some special

purpose su ch as t h e exact reprodu c t ion of geom etric al figu res orsu rface orn am e n t s are requ ired as for in stan c e i n prin t ing design sfor ch equ es

,bank n ot es

,e tc . I n su ch case s th e d1 aw in gs sh ou ld

be m ade as large as i s n ecessary for th e m ost exac t an d easiestcarry ing o u t of the figu res

, as in th i s way t h e preci sion of th edraw in g i s bett er kept by redu ct ion . I n su ch cases

,assum ing th at

th e orn am en ts are clear an d open w ith ou t sh adin g, th e redu c t ionm ay be c arried beyon d on e -ten th lin ear.

Th i s kind of reproduct ion sh ou ld presen t n o difficu lt ies e ith erto th e reprodu c tion or prin tin g .

I t i s qu ite differen t,h owever,w ith drawm gs o n s craper boards

Or grain ed paper. If it is kept in m in d th at w ith t o o great r e d-no“

t ion the gradation s of ton e of th e prin t w ill be des troyed, an d thatin the sam e degree the difficu l t ies of prin t ing w il l be in creased

,

care sh ou ld be t aken that redu ction is no t carried ‘

t o o far . W h enit i s fu rth er con sidered th at in a reprodu ction w ith t o

poin ts t o t h e squ are cen tim etre the in dividu al poin t s di sappear t ot h e u n aided ey e , an d t h e differen t thi ck layers of poin t s appear asclosed t on es

,t h e lim it of redu ct ion w i l l soon be fou n d.

If w e reckon accordin g to this v iew , we c an assum e th at thosekinds of paper w it h c oarse grain sh ou ld be redu c ed at th e

m ost o n e t h ird,those w i th a fin er grain a sixth

,at t h e m ost a

fou 1 th in order t o obtain good p rin t ing plat es which w i l l givelarge edit ion s . I n th i s Obviou sly w il l a good deal depen d o n t h e

ch arac t e1 an d m ore or les s rich 111 det ail exec u t ion of t h e draw ing .

Stil l t h e1 e are ph oto lith ogi ap h ic p 1 o c e ss e s su ch as t h e asph altprocess of Orel l F iissli 85 CO .

,wh ich con t ain s abou t 15

,000 poin t s

,

an d Bartos’process,which con tain s poin t s t o th e squ are

cen t im e tre,st il l for re p 1 o du c t io n i n large q uan t i t ies th ese p 1 o

cess es offer m any diffic u l t ie s . an d c an n ot th e i e EOi e really be takenin to accou n t when c on side 1 ing th is .

30 PHO'rO-L I THOG narH Y,

CHA PT E R II.

THE PHOTOG RA PHIC PROCE SS.

1 . T HE STUD IO.

Tm : arran gem en t of th e reprodu ct ion s tudio is essen tially differen tt o that for ordin ary portrait work . Th e gen eral poin t s of su cha rrangem en t s are described in detail in t h e h andbooks of D rs .

E der and V ogel , and these I m ay t h erefore om it so far as n o thingn ovel i s to be observed.

W e d is t ingu ish n e w be tween daylight and artificial light stu dios ;f urther

,t h ose in wh ich a cam era is u sed for m aking t h e n egative

a nd t h ose in which a dark-room i tself i s th e cam era .

'

T h e firstw i l l

,o f cou rse , h e u sed where oth er th ings besides reproduc tion s

have t o be m ade ; t h e arrangem en t w i thou t a c am era presentsm any advan tages for reproduc t ion work on ly . I n th e arrangem en t w i th art ific ial l igh t th e il lum in at ion of the objec t t o betaken i s effec ted as a ru le with a sou rc e of ligh t w h ich c an

app roxim ately replace daylight, and wh ich al so rem ain s as c ons tan t as possib le, and t h e e lec tric ligh t i s at presen t th e best.A l th ough o th er sourc es of l igh t are som et im es u sed

,th e el ec tric

ligh t in th e form of th e are ligh t for con t in uou s pract ical u se h as

t h e advan tage . For copy ing Oil pain t ings dayligh t i s t o be preferred u nder al l condit ion s, and for th is t h e best arrangem ent i st h e revol ving s t udio fi

‘e

T h e descrip t ion of a m odern studio wi th electric l ight as u sedi n th e K . u .K . Mi li tar-geograph isch en In s t itu t in V ienn a

,and

from which t h e s tu dio of t h e K .K . HOf-u nd S taat sdru ckerei was

copied,is g iven h ere . Th is studi o l ies seven m e tres below t h e

l eve l of the s tree t o n the sou th fron t of the bu ilding,an d i s shown

in Fig. 2 .

T h e preparation and dark room s are il lum inated with white,

yell ow , and re d l ight by m ean s of two 50-c .p . in candescen t electriclam ps for eac h colou r, an d besides this are provided with w indowscreen s of glass of th e sam e colou rs for daylight.Th e w indows Open in to an area 50 cm . w ide which ru n s roun dh e bu ilding . Th e ligh t ing is so arranged here th at besides the

o rdinary co llodion pla tes , very sen sitive gelatin e plat es c an bew orked. The room 0

,where t h e origin al i s placed

,i s fi tted up

4‘ Se e E de r’s

“Jah rbu ch fiir Ph o tograph ie ,

”1893, p . 231 .

https://www.forgottenbooks.com/join

34’

PHOTOA L I THOG R APHY .

the origin al an d th e focu ssing screen rest, ru n o n rail s, an d

are ab so lu t e ly iso lat e d from th e brickwork of th e bu i lding l n ordert o avoid any possib l e vibrati on s .Th e st an d for t h e original TT’is provided w ith screw fittin gs ,

cam s and wh eels , wh ich m ake it possible to rai se t h e origin al , t olower it ; t o m ove from right t o left , and vice -ve rsé, v e r t l cally an d

horizon tally, so as t o plac e its cen tre axi al W i th t h e o p t l cal axis ofth e l en s , as we ll as parallel t o t h e focu ssing screen in th e darkroom . T h e wh ole of t h e m ech an i sm lies at th e back of th e s tan d

,

so th at 't h e re is absol u tely no t h ing in fron t of th e origin al .Th e focu ssing tab le BE " i s con s tru c ted in a S 1m ilar m an ner to

t h e stand for t h e original , and i s m ovable in every direc tion int h e sam e way . I t carries in fron t two wood cl ips

,in wh i ch th e

board w i th t h e origi nal i s placed . T h e tabl e for th e origi nal,

l ike t h e focus sing t abl e , i s con s tru cted o n roll ers, wh ich run o n

t h e already-m en t ion ed rail s . I n order to be abl e t o fix t h ese assoon as a sharp focu s is Obtai n ed a brake i s fit ted . The placing oft h e original t able at th e di s tance from th e len s i s ac com m odat eda c c ording t o t h e size in wh ich it i s t o be reproduced, an d h asalready been estim ated. There rem ain s , t h erefore, on ly to t roubleabou t th e fin e focu ssing, which is very q u ickly e ffected.

For taking lin e or w ash drawings an d for en largem ents u p to80x80 cm . a S teinh eil w ide-angle apl anat is u sed

, wh ich gives n odist ort ion . The du ration of exposu re i s with su c h subj ec ts frome igh t t o t e n m in u tes . For sm aller subject s

,and prin cipally for

p h o tograph s o n wood, an orthoscope by V o igh tl'

ande r i s u sed, an d

t h e exposu re varies from four t o six m in u tes .A Zeiss an astigm at i s u sed for m aking au totypes . D urat 1on of

e xposu re from th ree t o five m in u tes . Coloured Obj ects, Oil pain

’

t

i ngs,e t c . ,

are t aken in t h e daylight studio . Th ey are prin t ed int h e daytim e in the open air, and in b ad w eather or u nder pressingcircum s tan ces in th e n ight by th e electric light.

2 . TH E G E NE RAL QUALIT I E S OF N E GATI V E S FOR. P HOTO-LITHOGRA PHY.

T h e n egative for photo-l i thograph ic work, for whatever m ethodit m ay be u sed, m u s t before all things possess t wo prin c ipal

q ual it i es wh en looked th rou gh it shou ld be as cl ear and as clean

as possible,o n th e other han d th e grou nd as wel l covered as

possib le .The deposit m u st n o t be of a black colou r ; from a wel l

drawn origin al absolu tely sat i sfactory n egat ives c an be preparedw ith ou t th e black colour . When a draw ing is redu ced wh ic hcon tain s grey l in es , dots, an d poin t s , as w el l as fu ll black on es ,t oned lin es w ill be visible as wel l as th e t ran sparen t ; w ith carefu lt reatm en t , th e n egat i ve m ay be so far corrected th at it m ay b e

u sed .If th is i s n o t effected, or i s n o t possible, th e re tou ch in g

o n the s ton e w ill be som ewhat troublesom e . Th e ton ed l in es prin tl at er than the tran sparen t ; these will therefore be overprin ted

TH E G E N E RA L QUA L I T I E S o r N E G A'I

‘

I V E S . 35

wh en th e form er have scarcely reac h ed th e correc t degree ofprin t ing. T h e ch oic e is th en on ly left e ith er to w eak en t h e lin esw h ich are t o o strong o r t o draw af terwards t h e fa in t o r n o t

prin t ed lin es .If th e g i o u nd i s n o t su ffic ie n t ly opaqu e it w il l p rin t th ro ug h .

Th is c an be rem edied by in t en sify i ng t h e n ega t ive,o r wh en t h is

i s n o t p o ssible t o pain t over it as w ell as possi bl e .

Tran sparen t spots are form ed o n t h e n egative by an im p u res il ver bat h or by du st flying abou t th e room . Th ese m u s t beSpotted o u t if in creased work later o n o n the s ton e o r z in c pla t e i sno t desired .

I n reprodu c in g fin e copper engraving s , it gen eral ly h appen sthat th e fin e grey h ai r-l ike lin es and t h e l igh t in t ers t ic es , i f t h eplate was n o t p roperly poli sh ed , appear less tran sparen t in t h e

n egat ive t h an t h e o t h er part s of t h e picture . I n develop in g t h eprin t t h e resu l t i s a part ly broken im age which c an on ly bet ou ch ed w it h con siderable t rouble . Th e n egat i ve c an be c orrec tedby t aking care to pain t over t h e tran sparen t part s . P rofessorHu sn ik recom m ends , when t h e pictu re is n o t t o o large, t o fasten a

tran sparen t paper o n t h e back of t h e n egati ve,and t o cover over

the glassy places w i th a soft l ead pen c il . Th ese part s t h en prin tsim u ltan eou sly w it h t h e hair-l ike lin e and devel op al so eq u al ly .

If,h owever, th e n egat ive i s l arge , an d th e pic tu re very c om pl icat ed ,

a glass posi ti ve pic t u re i s prepared in th e followin g m an n er : A

poli sh ed sh ee t o f glass is level led and coat ed w ith t h e fo llowin gs olu tion

Gelatine 6 parts by w eigh t .Su gar 1 partA m m on ium bichrom ate 1

Water 80 parts

W h en t h e solu t ion has dried th e gl ass plate is l aid o n th e

n egat ive an d exp osed till the deepest sh adow s h ave prin ted, an dit i s then developed in water . W h en dry this gl ass posit i ve i slaid on

' the back Of th e n egative so that every part of e ac h pictu refit s . Th e plates are then

“ boun d rou nd t h e edges w i t h papers trips so th at th ey can n ot shift . By t h i s — al t h ough som ewh attroublesom e— operation c an an u n sat isfactory n egat ive beren dered m ore even .

Th is correction can al so be effe cted in the follow in g m an n erT h e back of th e n egative is coat ed w ith raw collodion wh ichis fain tly colou red w ith an i l in e re d, eosin e or fu chsin e , al low edto dry , and t h en w ith an en graving n eedl e or a n arrow kn ifethe l ess t ran sparen t lin es m ay be scraped ou t

,so that t he re d

coll odion on ly rem ain s on th e tran sparen t places . Obviou slyal so th is c an be don e in th e reverse, by pain ting a fain t re d

o n th e t ran sparen t places w ith a bru sh .

By this last m eth od a tolerably e xten sive re t e u c l1ing .m ay b e

36 PHOTO-LI THOG RA I’H Y .

_

effec ted o n u n equ al n egatives, wh ich are t h e resu lt of n o t qu ite

eq ual ly black or al so very close drawn origin al s, from su bj ectsw ith very fin e lin es, s uch as c opper plate engravings

,or from

fin e ly-execu t ed l ithographs w ith v ery great redu ct i on . Fin al ly

i t sh ou ld be m en ti on ed that w i th in tellige nt retou chin g any h ad

n egative c an be u sed f0 1 photo lith ograph y, and t h e on ly q u es ti onn ow i s w h e ther it i s n o t bet ter t o t ake th e sh ortest way an d

prepare a su i tab l e n egat ive when th e original real ly perm its o fit s being don e . I n prin ti ng o n ch rom at ed gelatin e paper a goodresu l t c an be easier at tain ed from som ewh at foggy or thinn egatives t h an by prin ting w ith asph al t or oth er ligh t sen sit1vesubstan ce .

Th e fol lowing k inds of n egat i ves are u sed for th e variou sphoto li thograph ic p rocesses .

For th e t ran sfer process w ith ch rom at e d gelat in e paper or

direct prin ting o n ston e or zinc dire ct, a reversed l i ne or au totypen egati ve .

For Orell an d F ussl i’s process, a re ve rsed ordinary half-tone

n egative .

For Bartos’ process and for photogravure on ston e , a di rectordin ary half-t on e n egative .

3 . PRE PARA TION or THE D I RE CT GLA SS N E GATI V E .

T h e preparat ion and cl ean ing of the plat e glas s is as followsFirst of all th e plates are rough en ed w ith a piece of sharp pum iceston e on t h e extrem e edges t o the breadth of abou t 0 5 cm . in

order to preven t the frilling or floating off of the collodion film .

Th i s i s very littl e trouble con side ring the advan tage it olfersA fter being edged the pl at es are placed in a solu t ion of

N itric acid chem ically pu re 1 partWat er 10 parts

In stead of n itric acid, chrom i c acid m ay be u sed, b u t th i s i s no tabsolu tely n e c e ssa1 yA ft er o n e or two hou rs th e plates are taken ou t of the acid

bath ,w ell w ashed u n der a strong wat er rose

,an d dried in a

place free from du st . Then the plates are w ell rubb ed w ithtin ctu re of iodin e solu t ion w ith a p ad of cl ean filter paper

and then polished with 50 per cen t . alcohol . This preparat ionmu st be don e w ith absolu te accu racy, and thu s they m ake all

substrata of album en,india-rubber solu tion , etc ., for direct

n egat ives u n necessary.

P lates w h ich have been previou sly u sed are placed in pu rewater t ill the collodion film h as becom e loose, an d are thenscrubbed w ith a st ifi bru sh

,treated for som e h oil rs to a bath of

cau st ic soda, an d then tre ated as above, when they m ay be used1 again .

PR E PA R A T I ON OF TH E D I R E CT GLA SS N E G A TI V E . 3 7

For reprodu c tion of sim ple l ine draw ings iodi zed collodion is

u sed wh ich consists of 2 per cen t . raw collodion c om posed o f

E th er c cm .

A bsol ute alcoholPyroxy lin 40 g.

I odizing is don e w ithSodium iodide 15 g.

Cadm ium 1 5

8

P otassium iodide 1

Th e last salt i s di ssolved in a few d1 0ps of dis t il led wat er, theo th er sal t s are di ssol ved in on e part of t h e absolu t e alc oh ol .The iodi zing sol ution i s fil tered in t o th e raw c ollodion , w h ichh as alre ady

c

been all owed to settle and fil tered , an d allowed t o

stan d for som e day s .Th e sen si ti zing solu t ion i s n i trate of silver in t h e proportion

o f 1 : 10, w ith l arger si zes 1 to 12 1 t o 14 and th e si l ver bathi s fain t ly ac idulat ed w i th chem ically pure n i tric acid .

For a m onoch rom e su bj ect th e e xp o su1 e las t s according to thes i ze of th e reproduction ,

an d th e rapidi ty of t h e obj ec t ive,from

three to t e n m in u t es .For developm en t an iron developer i s u sed , con s isting of

W at er 4000 e cm .

Ferrou s su lphat e 150 g.

Copper su lphate 75

A l coh ol (40p e 1 c en t .) c om .

Glacial aceti c acid 125

The iron developer, w i th addition of su lphat e of copper

,i s t o

be preferred for sh ort exposures to iron and lead developer. Ifthe plate has been correctly exposed t h e im age gradu al ly appearsaft er a short t im e , an d very soon gets vigorou s . Wh en t h e detail sappear in the deepest shadows the developm en t m u s t be im m e di

ately stopped , oth erw ise foggin g w ill en su e . If t h e im age doesn o t gam vigour by long developm en t it was u n der- exposed ; w itho ver-exposu re t h e im age appears qu ickly an d rem ain s thin . Th e

developer, when . fresh , Works fairly qu ickly ; older developerswork slower, b u t give v ery clear n egat ives .For very fin e l in e draw in gs or reproducti on s of copper-plate

e ngravings the developer is u sed som ewhat weaker, and o n e -fifth

o f it s vol um e of water added . Th e developm en t t akes som ewhatlonger ; th e fin e lin es rem ain , however, very clear .

A fter developing th e plate is wel l washed an d th en in ten sifiedfirs t w ith a solu tion of

W aterFerrou s “su lphateC i tri c acid

38 P HOTO-L I THOG R A PH Y .

to wh i ch a few drOp s of a 1 : 12 silver n i trate solu tion h ave beenadded . Care sh ou ld be t aken th at in th e first in ten sificat iont h e glassy p lac e s

'

re m ain clear. Wh en,t h erefore

,t h e desired

opaci ty is at tain ed th e p late sh ou ld be im m ediat ely was hed . Tool ong i n t en sific at ion fogs t h e fin er l in es ,T h e plate sh o u ld be fixed wi t h 5 p e r cen t . sol u t ion of po tassium

cyan ide. For t h is,h owever

,a con cen trated sol u t ion o f hype

su lph it e of soda can be u sed .

A ft er wel l wash ing, t h e n egat ive w i ll sh ow,wh en exam in ed by

t ran sm itted l igh t , w h et h er t h e grou nd i s opaq u e en ough ,or

wheth er a furth er in ten sificat ion i s n ecessary. Wi th correctm anipu lation th is first in ten sificat ion w il l be su fficien t for fin e ,w el l -prepared drawings .If

,h owever

,t h e opacity proves to be too l ittl e , after thorou gh ly

w el l w ashing, t h e second in ten sification or blacken ing i s e fie c te dw ith a con cen t rated solu t ion of m ercu ric c h loride in di s t i l ledw at er, wh ich i s allowed t o ac t t il l th ere i s a di st in ct prec i p i tat ean d th e film has becom e grey. A fter w e ll wash ing t h e plat e i sflow ed over w i t h sol u t ion of t h iosu lphate of gold t ill th e grey

q u icksil ver prec ipitate has becom e absol utely b lack . The goldsolu t ion con si s t s of

(A ) D ist i ll ed water 1000 partsC h loride of gold 1 part

(B .) D ist i lled wa t er 1000 partsHypo- su lph ite of soda 10

Im m ediately before u se solu tion A is added w ith con st an tstirrin g t o solu t ion B

,and a fe w drops of am m on ia added . If

th e desired blacken in g i s n o t effec t ed w ith o n e appl ication t h e

Operation m u st be com plet ed .

The sol u t i on of gold, when kept in the dark, w ill keep a longtim e .

For fixed n egative the fe llowm g 1n t e n sifie rs have been u sed w ith

good resu l t s .

1 . I n t e n s ifie r with pyrogal lol .

(a .) S il ver n itrate . 5 parts by weightD is t i ll ed wat er 75

To this solu t ion 1s added

(b.) Cit ric acid 5 parts by w eightD i st i ll ed water 75

(a.) Pyrogallol I 25D i st illed water 150

2 . The h ydro c h in on e in ten sifier recom m ended by Baron Hubl :Hydro ch in on e 10 part s

1000

To th i s as m u ch acid is added as w ill keep the so lu t 1on clear for

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40 13

11 011

0-111 1 q RA PHY.

t ion s o f u ran ium and fe rridcyan ide is u sed, which i s com posed oftwo sol u t ion s

(A .) Uran ium n itra te 8 parts by weightSugar 8

Wat er 350

(B.) Pot assium ferridcyanide 8 parts by weightSugar 8

Water 350

The n egat i ve is first flooded with th e u ran ium solu tion and thenw ith th e re d pru ssiat e .

A n o th er process of in ten sifica tion recom m ended by Prof. E derand To th is t h e se -called lead in ten sifier.The som ewhat u nder-exposed n egative ough t on ly t o be

developed w i th iron,

fixed wi th hyp e , and m u st t h en be w el lwash ed . I t is finally wel l rin sed with di s ti lled water, and thenplaced in a filt ered solu t ion of

Lead n it rate 4 parts by weightP o tassium fe rridc van ide 6

D ist illed water 100

A fter a few m inu tes it becom es absolu tely opaq u e in th e c overed

part s . The n egat ive is allowed to rem ain in the ba th t ill it hasat tain ed t h e desired den si ty . On th e sil ver m olecu les of theim age a pale yellow precipitate h as form ed by th e ac t ion of th el ead bath . Th e fe rridcyan ide of potash is reduced by t h e sil verto yellow ferrocyan ide of potash , and gives th en , w i th t h e leadsalt

,an in soluble com pou n d

,ferrocyan ide of lead . By t h e act ion

of am m on ium su lph ide t h e u n stable l ead sal t i s con verted in to astable salt .

A s soon as the n egat ive has been t aken from the lead bath an d

w ell washed, t i ll th e wash ing wat er n o longer gives a blu e prec ip itate , it i s flowed over w ith d ilu te am m on ium su lphideSodium su lphydrat e m ay also be u s ed . Th e im age bec om es blackin stan tan eou sly . Th e n egat i ve becom es gen erally vigorou s ; if,however, it was exposed too lon g the fin e hair lin es an d poin ts veilo ver very easi ly.

I f the n egative i s n o t suffi cien t ly in ten sified, which m ay happenw ith v ery m u ch under-exposed n egat ives , it sh ou ld after wellwashin g, an d before treatin g w ith am m on ium su lph ydrate, belaid in a bath of

Cadm ium 10 partsD ist ill ed water 100

in which it becom es still whiter, an d shou ld then be t reated w ithth e am m on ium su lph ide . The lead

,th e cadm iu m ,

an d t h e silvero f t h e bath are c on vert ed by the amm on ium su lphydrat e in tosu lphide .

The n egat i ves treat ed w ith cadm ium have a yellowisht in ge, whilst those treated w ith lead are pu re bl ack. Fo r clear

PR E PA R AT I ON o r A UTOTYP E N E G A TI V E s . 41

ing u p th e wh i te-l ead im age wh en i t is t o o v igorou s or is foggyhyposu lph ite o f soda o r a dil ute sol u tion o f pot assium cyan ide c anbe u sed . Th is m an ipu lation , however, requ ires great c are . Th e

n egat ive treat ed w i th am m on iu m su lph ide if foggy c an be cl earedu p w ith h ydroc h loric ac id, u sed w eak an d repeat edly poured 011

an d o ff, w i th care fu l wa tch ing of t he ac tion . A fter this it m u stb e w ell washed .

Th e l ead solu tion w il l rem ain cl ear for w eeks , an d if it begin sto work slowly c an be freshened u p w ith addi t ion of lead n it rat ea n d fe rridcyan ide of po tash .

If stri pp ing negatives are to be prepared, it i s advisabl e , w ith“

t h e lead in t en sified n egatives,to give t h e glass pl at e a pre lim inary

rub w ith vaseli n e oil , to well wash , and t h en to coat w i th raw

collodion .

Hu sn ik’s graphite in ten sification i s stil l to be m en t ion ed, which ,

in som e cases , m ay be of great service, b u t requ ires practice an d-c are .

Th e expert photo-m echan ical w orker w i ll ade p t on e or the otherm ethods for h is work, an d as soon as h e can work safely an d wi tho ut hesi tation he w ill adhere t o that .

4 . THE PRE PA RA ’J'

ION or'

A UTO’

TYPE N E GATI V E S or BLA CK A ND

COLOURE D D RAWINGS .

A s regards th e preparation of au to type n egatives from sim pl e‘

black originals— wash drawings— th e above phot ograph ic proc esses are qu ite su fficien t . FOI 1 t aking pain ted origin al s— su ch as«o il pain t ings, water-colou r draw in gs , fresco, an d pastell drawings — an orth och rom at ic col lodion m u st be u sed if a correctrendering of t h e ton es in th e n egat ive is t o be ob tain ed .

In o ur studio w e have obtained excellen t resu l t s w i th tw o

kinds of colou r sen sit i ve collodion . Th ese are t h e i soch rom at iccollodi on em u l si on prepared by D r . E . A lbert an d th at suggest edby Major von H iib l . I n u sing th e form er, t h e glass plat es as soonas th ey are tak en o u t of th e acid bath and w ell wash ed m u st be

given a substratum of the fol low in g solu tion

White gelatin e

t o which i s addedGlacial acetic acid 15 partsA lcoh ol 10

Th e solu tion shou ld be fil tered an d coated whils t warm , an d theplate dried in a room free from du st at least 15° R .

For the produ ct ion of th e se n sit ive n e ss ,‘

o r for the produ ctiono f the correct reprodu ction of

‘

the colou rs,t wo eoside of. silver dy es ,

R . an d P ., are u sed . The P .

‘

dy e gi ves great sen sit iveness , and i se specially su itable for portraits, landscapes , etc. I n using t h is a

42 P HOTO-. LI THOG RA PHY .

correct reproduct ion of th e r e d m u st be aban don ed,wh il st th e R .

dy e gives an absolu tely correct colou r ren derin g b u t re q u 1re s

abou t double th e expos ure T e n c em . of th e eoside of silversol u t ion are added to 100 c om . of t h e em ulsI On . Wh en colouredth e em u l sion W I ll on ly keep for o n e or two days .T h e t im e of exposu re w ith t h e R . dy e is n orm al ly from o n e -and

a-half t o three m in u t es .A fter exposure t h e plate m u st be w el l washed u n der a tap and

t h en allowed t o t h orough ly drain,or oth erw is e developing streaks

wil l sh ow .

Hydro ch in o n e developer is u sed for developing, c o ns1sting ofthree solu t ion s

(A .) D ist il led water 500 part sSodium su lph ite 200

P otassium carbon ate (pu re) 200

(B .) Hydro ch in on e 25

A l cohol (96 100

(C .) A m m on ium brom ide 25

D ist il led water 100

This devel oping liqu id is con cen trated, and i s u sed asfoll owsSolu tion A . 100 part s

To obtain h ard n egatives solu tion B i s in creased from 1 to 5t im es . A m ixt u re of 1 50 part s of th e above sol ution with 1000part s of d ist i ll ed water form s t h e actual developer. By th e add it ion of m ore con cen trat ed developer or increasing t h e q u an t ity of

wat er t h e developer m ay be su ited to the ch arac ter of th e subj ect .Th e developer m u st be freely flowed over th e plat e , and th en t h eplat e fixed w i th sodium hyposu lphite . I n t e n sific ation i s effectedw ith

(A .) Pyrogall olCitric acidD ist illed water

an d when dissolvedGlacial acet ic acid 25 drops

are added .

(B .) S ilver n itrate 10 g .

D is t ill ed water 100 c om .

Im m ediately before u se 100 parts of solu tion A are m ixedw ith5 part s of solu t ion B

, and t h e in ten sificat ion con tin u ed till th edesired den si ty is obtain ed . N egatives c an be redu ced by placingthem wh i lst dam p in a solu tion of

Potassium perm angan at e 1 partD is tilled wat er 300 part s

Wh en th i s h as acted su ffi c ien t ly , the plate is we ll washed,

PR E PA RA TI ON OF A UTOTYP E N E G A T I V E S .

flowed over with a five per cen t . solu tion of potassium cyan ide , andt h en w el l w ash ed. Wh en t h e dy ed em u l sion i s u sed th i s m u st bedon e , after developin g, in re d ligh t .

A very excell en t m ethod of preparing an orthoch rom ati ccol lodion em u l sion has been described by H iib l ,* which can be u sedeith er w e t or dry . R epeated t rial s m ade in the Im perial M il itaryGeograph ic al In s t i tu t e , in o ur establishm en t, an d in the Ph ot ograph i c In st i tu te in V ien na h ave proved th e advan t ageou s u se oft h i s m ethod for orthoch rom atic w ork . Th e raw em u lsi on

, ao

cordin g t o H iib l , i s prepared as follows — 40 g. of silver n itrateare dissolved in 50 c cm . of warm di still ed water, and

‘ as m u cham m oni a added as w il l give a c lear sol ution ; t h en 100 c om . of

al coh ol are added an d t h e wh ol e allowed t o cool . 30 g . ofam m on ium brom ide are di ssol ved in 35 c cm . of wat er and 70 c cm .

of absolu t e alc oh ol w ith gen t l e h eat .

To m ake t h e em u l sion 450 c cm . of fou r per cen t . raw collodionare pl ac ed in a strong glass flask wh ich w ill h old a l itre

,an d t o

th i s in th e dark room t h e sil ver solu t ion added . Som e of th ewool separat es o u t

,b u t by V igorou s sh akin g t h is can agai n b e

di ssol ved . A part of th e silver salt al so rem ain s su spended in theliq uid in th e form of fin e crystal s . The am m on ium brom ide isadded in th ree or four part s wh il st w arm . A fter sh akin gth orough ly for several m in u tes th e em u l sion i s precipit at ed bydi stil led wat er, wh ich i s repeat edly added till th e separa tion iscom plete . T h e em u l sion ,

w h ich is n ow powdery, is plac ed on al in en fil t er

, wash ed several tim es w i th distilled w ater, squ eezed t opress o u t th e las t of th e wat er, dam ped two or three t im es W i thalcoh ol

,an d t h en pressed . Wh il st s t il l dam p w i th alcoh ol th e

em u l sion i s di ssolved in from 800 t o c cm . of alcoh ol an d

e th er,m i xed w ith 05 grs . of codein e , an d allowed t o rest for som e

day s , w h en it w i ll be ready for u se .

Th e preparation of t h e eoside of si l ver solu tion i s efi e c t e d asfol low s - 10 g . of yel low - shade eosin e are dissolved in 250 c cm .

of boilin g wat er and 5 grs . of silver n itrat e in 50 c cm . of wateradded h o t . The solu tion i s allowed t o set tle , th en filt ered

,an d

t h en washed first with b o iling wat er an d then w ith alcohol on th efilter

,an d th en dried in a dim ly-ligh ted room . _

To prepare th e dye sol u tion 0 5 g . of th e dry eoside of sil ver an d1 g . of am m on ium acet ate are gen tly heated together in 30 c cm .

of alcohol til l dissol ved,th en 120 c cm . of alcohol and 10 c cm . of

glac ial acet ic acid are added, an d th e whol e filtered . For platest o be exposed w e t , 5 -10 c cm . of glycerin e are added . Th e em u lsion is sen siti zed by a ddin g on e -ten th of its v olum e of dy e , an dshou ld be w ell sh aken before coatin g t h e plat es . Th e glass plat esshou ld receive a prelim in ary subs tratum of gelat in e or in diaru bber , so th at th e .frillin g of the film an d im pu rit ies of the glassplates m ay be t ot ally avoided .

“E ncy clopaedie der Ph o tograph ic , He ft 3

,and E der

’s

“ Jah rbu ch,

1892, p . 387 .

44 PHOTO-LI THOGRAPHY.

For sm all sized plates th e em u lsion is u sed ‘ som ewhat thicker”

th an for larger,and for th e latt er it shou ld be dilu ted w i th alcohol

an d e th er. A fter coat in g t h ey sh ou ld be dried at abou t 15° C .,and

then for som e m in u t es exposed t o a tem perat u re of 30° C .

Th e plat es sh ou ld be developed w ith th e follow ing m ixtu re z25 g . of sodium su lph i te shou ld be dissolved in 40 c cm . of w armwat er, t h en 10 g . of glycin e added and 50 g. of potassium carbon at e , at firs t in sm all qu an t i t ies in con sequen ce of th e e vo lu

t ion of carbon ic acid . W h en cool abou t 75 c cm . of a th in pastyliqu id w ill be ob tain ed, w h ich m ay b e kep t as a s tock solu t ion ,

and before use m u s t be w el l sh aken and dil u ted w ith from 12-15

tim es th e q u an tity of wat er. W e t plat es shou ld be w ash ed beforedevelopm en t

,an d th e developer flowed o n ; dry plates sh ou ld n o t

be w ash ed,and sh ou ld be developed in a di sh .

Th ey sh ou ld be fixed in sodium hyposu lph i te . Th e in t e n sific a

tion m ay be e ffe c t e d with m etol (se e p . and th e blacken in g asd escribed on p . 38 .

Ob viou sly t h e col lodion em u l sion m ay be u sed for ordin arywork u ndyed .

Th e q u al i t ies of t h e cross-l in ed screen an d th e dis tan ce o f th e

s am e from th e s e n s it ive plate w il l b e describ ed in C hap ter V .

5 . PRE PARAT ION OF R E V E RSE D N E GATIV E S.

For the differen t pho to-l ith ographic work d irect and reversedn egatives are u sed ; for th e tran sfer process direct n egat i ves areu sed ; for prin ting direct o n to th e s ton e or plat e, reversed n egative s .

For m aking the latter variou s m eth ods are u sed, the prin c ipalof wh ich are as follow s

(A .) E X POSURE THROUGH A PRI SM.

Th i s m ethod i s, on accoun t of it s in con ven ien ces an d difficu l ti es ,

on ly u sed wh en it can not be possibly avoided .

Fig. 6.

ST RIPPJNG N E G A T I V E S . 45

Fig . 5 sh ows the arrangem en t in wh ich t h e prism a i s placed infron t of t h e le ns b . Th e

.p 1 ism i s t h ree c orn ered an d t h e angle

t urn ed t o t h e obj ective i s a right angle . T h e hypoth en u se i ssil vered . I t i s m ou n t ed in brass o r n ickel ; o n t h e m ou n t is a

screw,by m ean s of w h ich it i s fasten ed to t h e obj ec t ive , so t h at

t h e side op posit e to t h e hy po th e n use lies u prigh t t o th e side of t h ecam era

, and thi s posi tion m u s t be an exact right angle t o th e

foc u ssing screen . Th e cam era itself m u st b e absolu t ely h orizon t al .Th e s ubj ec t t o be taken

,in stead of being in fron t of t h e cam era,

i s placed sideways to th e prism . T h e im age passes through a’,

fa ll s o n the sil vered hypo then u se a"

,from there through t h e

obj ecti ve b,thro ugh th e box -sh aped extension 0 and t h e cam era d ,

o n to t h e sensi t i ve plate,w h ich i s n o t v i sibl e in th e diagram .

Th e exposure w ith t h e prism i s abou t 33 th l on ger th an u su al,

becau se a port ion of th e ligh t is absorbed by th e p rism .

(R ) P LA CING THE PLATE THE WRONG WA Y ROUND IN TH E SLI D E .

Gen erally,for m aking reversed n egati ves of l i ne draw in gs

,it is

qu i te su fficien t t o place th e sen si tive plat e th e wrong way rou ndin t h e dark slide or in th e carrier, so t hat th e film side

,in stead of

bei ng t owards th e obj ective, is t urn ed t owards th e Operat or . Itis

,of c ou rse

,ab solu tely essen tial t o u se on ly glass plat es which

are absolutely clean an d which con t ain n o particles of san d, air

bubbles, e tc .,which w ou ld show o n t h e prepared n egative as

points . A fter sen sitiz in g t h e plat e,the back of it m u st b e

thorou ghly cl ean ed , for any sm u dges or drops w ould be v i sibl e onthe n egat ive . Obviou sly great c are sh ou ld be t aken al so in

clean in g th e plat e t o m ake as l it tl e du st as possible . I n th e

Im perial an d St ate Prin ting W orks n early al l th e reversedn egat ives are prepared m ost sat i sfact orily in th is way .

Th e photograph ic m an ipu lation s,t h e preparat ion

,sen siti zin g

an d devel oping of the plat es, etc .,i s exact ly t h e sam e as w ith

direct n egat ives .

(a.) STRIPPING N E GATIV E S.

There are variou s direction s for m aking strippin g n egatives .A n india rubber solu tion con sist in g of equ al part s of ben zol e an d

c h lorof01 m ,in which an equ al part by w eigh t of in dia-rubber 1s dis

solved , is u sed as a su bstratum . Whenb

th e solu tion has b e c om e

q u ite cl ea1 t h e u n reversed an d u n varn ish ed n egative 1 s coat edw ithit . Wh en th e film i s dry , a coat ing-of raw collodion

,to which som e

drops of cas tor oil have been added, i s given . Wh en this film i squ i te dry , it i s c u t t h rough n e a1 th e edges w i th a sh arp kn ife

,an d

t h e glass plate an d film placed in a di sh filled w ith water, when .

t h e n egative film w i ll loosen from t h e glass an d after som e tim ew il l swim in the wat er. I n thi s operat ion th e u se of force m u stbe avoided . The film i s lifted from the water by placing a card

46 PHOT O-LI THOG R A PHY.

un dern eath it , carefu l ly dried w ith fibre paper,th en laid flat and

pressed som ewh at between tissu e paper . T h e n egat ive preparedin th is way h as m an y disadvan tages . First of all

,t h e fi lm i s easily

in ju red,and, t h erefore , th e edges sh ou ld be bo un d w i t h s trip s o f

paper in order t o protect it from t earing ; fu rth er, t h e fi lm i se asily folded and does n o t rem ain acc u rat ely of th e sam e size

,

wh ich m akes it u sel ess for certain p urposes . Moreover,t h i s

process is som ewhat cost ly. It is n ow alm ost en t irely replaced bya process in wh ich a gel a t in e substrat um i s u sed .

Th i s p roc ess i s as follows - The u n varn i sh ed n ega tive i saccu rately levelled w ith a level and coated 2 m m . t h i ck w i th a

solu t ion of

W h it e gelatin e 20 part s by weigh t .D istilled w at er 500

Glyc erin e (ch em ical ly 25

Glacial acet i c acid 10

A lc oh ol 36 0" 50

Th e above qu an t i ty 1s q u 1 te su ifi c ie n t'

fo r at least fou r n egatives21 x 26 c m . Many om i t t h e ace t ic acid , b u t I h ave fou n d t h atit is an advan tage for the slow drying , t h e pl iabil i ty, and th e keeping o f its size of th e n egative

,to u se ac e tic ac id in m oderate

q uan t i ties . To a c ertain degree th e addi t ion of glycerin e al soe ffec t s th is , b u t n o t su ffic ien t ly enough . Before pou ring o n t h e

gelat in e sol u t ion , th e plat e m u st be absolu tely dry . A ny air bell s‘ form ed whils t coating m u st be pu sh ed t o t h e edge of t h e platew i th a piece of card . T h e plate m u st be dried spon tan eou sly ina room as airy and as free from du st as possible . I n order to prot eet th e film from du s t part icles , i t i s advisable t o give it a paperc ap or cardboard cover, wh ich all ows t h e access of air

, an d

obviou sly it ough t n o t t o tou ch th e fi lm .

When t h e gelat in e film h as becom e th oroughly hard, it sh ou ldb e coat ed w i th n egative varn ish

,and, aft er again dry ing, sh ou ld

be c u t rou nd th e edges w i th a sh arp kn ife righ t through t o t h e

glass and stripped from t h e plate .

If t h e glass was wel l-clean ed and prepared, as h as beenpreviou sly described on page 41

,any gelatin e film th u s p repared

w i ll well and safely strip w ithout a substrat um .

W i th dirty or o ld plat es,a substratum of a 1-2 sol u t ion of

in dia-rubber sh ou ld be u sed .

A ft er strippin g, th e ,gelatin e film s are best kept be tween fil ter

p apers and u nder glass plates .

https://www.forgottenbooks.com/join

48 PHOTO-LI THOGRA P HY.

defective tran sfers . A l arge proportion of carbon ic acid wil l produ ce th e sam e fau l ts , which m ay , however, be rem edied by a sm al laddit ion of am m on ia short ly before u se .

Gelat in e is very hygroscopic, and therefore attracts m ois tu refrom th e room where i t i s kept and dissolves com ple tely in warmw ater . E ven 111 very great dilution

, 3 .g. 1 : 100, it se ts again t o a

j el ly i n t h e cold, b u t loses t h e sett ing power after bei ng repeatedlywarm ed, o r it t h e tem perature was raised con siderably h igh er thanwas n e c e ssa1y to m el t it . D am p gel atin e decom poses in th e air

very soon ; t h e decom positi on,h owever

,can be del ayed w i th

salicyl ic a iid carbolic acids and glycerine . G reasy gel at in e c an beim proved by t h e add ition of 5 p e r cen t . of alcoh ol . Too softgela t in e c an b e h arden ed w ith ch rom e alum

,and o n e part of

chrom e al um m ay be u sed to 200 parts of gelat in e, an d by this

addit ion t h e m el t ing poin t i s rai sed abou t 7 °C . Too hard gelatin egives rise to th e form at 1ou of bubbles . I f the gelatin e solu tion 1s

,

s ligh tly acid it i s n o t a disadvan tage .

The gelat in e u sed in o ur establish m en t i s of Fren ch m ake, an d

is kn own as tran sparen t white gelatin e, and i s al so very su itabl efor coll otype . I m en tion this becau se t h e gelatin e freq u en tly givesrise to fai lure . For practical work, then ,

it i s advisable .t o stickt o o n e m ake when it h as been proved to ‘be absol u tely satisfactory.

To those wh o wou ld st udy m ore closely this very im portan tm aterial for photo lithography and collotype

,I wou ld s tron gly re

com m e nd the brochu re Ueber die R e ac tio n e n der Ch rom saure n

u nd de r Chrom ate auf Gelatin e, Gum m i , Zu cker u nd andere Substan zen organ ischen Urspru nges in ihrer Beziehung zu r C hrom atphotograph ie,

” by Professor E der,in which the m os t exhau stive

in form at ion o n the application of these two m aterial s so im portan tin photography, gel at in e and the chrom ate sal t s , 1s given in a

con ci se, pop u l ar, and easily u n derstood form .

(B.) THE CHROMATE SALTS.

The sen sitiven ess to ligh t of the di fferen t ch rom ium com pou ndsform s at presen t the fou n dat ion of several photograph ic an d ph o tom ech an ical processes .A cc ording t o D r . E der, V auqu elin discovered in th e y ear 1 798

ch ro rm u m and chrom ic acid, and m ade at th e sam e tim e t h e e h servat ion th at ch rom ic acid form ed w ith sil ver a carm in e re d salt ,which becam e pu rpl e-red by the action of light . I n th e year1832 th e philosopher D r . Gu s tav Su ckow ,

in his work,“ D ie

chem ischen VV irkunge n de s Lichtes ,” stat ed that th e ch rom ate

salts w ere also sen si t ive to light in the absence of sil v er if an

organ ic substan ce was added, as in the light lower (green) oxidation produ c t s w ere form ed . I n 1839 Pon t on added to V auqu el in’sand S u ckow s discoveries, and discovere d th e ph otograph ic applicat ion of ch rom ate of sil ver, th e light sen sitiven ess of potassium b i

chrom at e o n paper. The chrom ates are p er se s table in ligh t in th e

SE N SIT I Z I NG . 49

presen ce of organ i c substan ces , howev er, su ch as gelatin e , album en ,

gum ,etc ., a q u i ck redu c t ion of th e sam e t akes p lac e in ligh t . Talbot

finally fou nd th at a m ixtu re of gelat in e and a chrom at e bec am ebrown m ligh t , and lo st at th e sam e tim e its solubili ty in warm wat erau d i t s power of swelling u p in cold wat er. A ccordin g t o th e sam e

au th ori ty S lm p le potassium ch rom ate is from 20 t o 25 t im es l es ssen sit ive t o light th an potassium bichrom ate, an d t h e sim pl eamm on ium ch rom at e shows th e sam e sen sitiven ess t o ligh t asam m on ium bich rom ate . Fo r ph ot o-lit h ograph y t h e l at t er salt ,potass ium bich rom at e

,i s v ery im por t an t, and it h as the chem ical

form u l a of KzCr2O7 .

(c.) TH E" G E LAT INI ZING .

The gelatin izing of th e paper and the preparation of the gel atin esolu t ion i s effected as foll ows 1

Th e gelatin e, accu rat ely w e 1gh e d o u t , is placed in sm all p ieces inthe proper quan t i ty of wat er, eith er in a large m easu re or som eoth er vessel , an d placed in a w ater bath an d im m ediat ely heated .

It i s advisable t o place th e v essel con tain ing t h e gelat in e in t o t h ewat er bath before th e latt er i s h eated, so that both m ay heattogeth er an d fractu re of the glass be thu s avoided Wh en th e

gelatin e i s com pletely di ssolved t h e warm solu tion i s fil t eredt h rou gh a lin en filt er, an d so th at it m ay n o t be cooled t h e v esselin to which t h e gelatin e solu tion i s fil tered i s also placed in th eWat er bath .

Whilst still warm and l iqu id the gelat in e is pou red o n t o th e

previou sly prepared paper, an d any bubbl es of air brough t t o theedge of th e sheet with a strip of st iff paper or a feath er.I t shou ld be especially n oted t h e gelat in e solu t ion sh ou ld b e

u sed u p as qu i ckly as possible or else it w ill det eriorat e . Gelat in ewhich rem ain s for a long tim e in a state of solu t ion becom es softan d flu id

,an d if th e chrom at e bath i s n o t w el l cooled a part ial or

com plet e dissolvin g of th e sam e t akes place in sen sit izin g or laterin washing an d developing.

(D .) S E NSI T I Z ING .

The first thin g to be treat ed of is t h e preparation of the bichrom ate bath . Th e n ecessary q u an t ity of t h e bich rom at e of potashis ru bbed u p as fin e as possible in a porc elain m ortar w ith a lit t l ewater ; it shou ld th en be t ran sferred t o a larger

,

flask an d th e

n ecessary qu an t i ty of water added . W h en al l t h e bich rom at e isdissolved t h e solu t ion sh ou ld be filtered

,an d so m u ch am m on ia

added as w i l l con vert th e oran ge yellow colou r in t o a s traw yellow .

Th i s bath c an be kep t , in a dark c ool room ,fit for u se for a long

t im e . T h e proport ion s for th e solu t ion are

P otassium bichrom at eWat er

50 PHOTO-L ITHOG RA PHY.

and as m u ch am m on i a as w i ll m ake it s traw colou red. T h e bathis n eu t ralized wi t h am m on i a or a soda or potassi um sal t , becau sesol u t ion s of t h e bich rom at e sal t s h ave th e property of dissolvinggela t in e even in t h e c old .

T h e day before being u sed th e sh eet of gelat in i zed paper 1splaced in this b ich rom ate bath , wh ic h sh ou ld be as c old aspossible ; in sum m er it sh ou ld be cooled wi th ice . I t sh ould becom pl e tely im m ersed in this bat h , so t h at th e sol u t ion covers everypart of th e sh eet t o th e dep th of 1 -2 c m .

,and Sh o u ld be left in it

abou t t h ree m in u tes ; care m u st be t aken th at n o air bell s form o n

t h e gelat in e . If t h i s shou ld h appen th ey sh ould be rem oved w itha soft bru sh

,which ough t n o t t o be u sed fo r any o ther purpose .

On t h e places n o t covered by t h e bic h rom ate sol u tion,wh ich h as

bee n kep t o ff by th e air be ll s , t h e paper wou ld n o t be sen sit i ve toliO 'h t .D

Fo r ordin ary prin t ing th e paper m ay be dried in t h e air byplac ing it o n a board, or bet ter o n a rack ; for be t ter class work,an d ac t ually for all w ork, it i s be t ter to sq u eegee t h e paperas soon as it i s rem oved from th e bic h rom at e bath o n a Sh eet ofpl ate glass wh ich has been wel l cl ean ed and poli sh ed w i th t alc

,

t h e exc es s of sol u t ion or any air bubbles being rem oved bysq u eegeeing thorough ly u n der blo t t ing-paper . Many operatorssligh t ly grease t h e glass plate . I h ave fou nd th at t h is i s n o t

n ecessary if a su ffic ien tly cold sen sitizing bath i s u sed,t h e plate

glass t horoughly clean ed and well rubbed w ith t alc, and it i s dried

in an airy room . I t i s advisable to see th at th ere is always ve n tilat ion in th e drying room ,

and t h e m ore t h is i s don e th e bet t er thepaper w i l l behave in th e subseq u en t operat ion s .

To com pletely dry , th e paper requ ires when dry ing by itselffrom th ree to fou r hou rs from t e n to twelve hours wh en squ eegeedto glass . The best way i s to sen sitize the paper in th e aftern oonor t h e even ing, so th at it m ay be u sed the n ext day in th e m orning . Th e paper wh en sen sit ized will, when properly kept in a

dark c ool room ,be in a fit s tat e t o u se for several days . By

squ eegeein g o n to th e pl ate glass t h e paper takes a very highglossy su rface , an d thu s in prin ting c om es in to in tim at e closecon tac t with th e n egative . I n exposin g, th erefore , every fin e lin eappears w ith great er precision th an on paper which h as becom e

wrinkled and u n even , and which has n o t been previou sly glazed .

I t Sh ou ld also be m en t ion ed that this gloss is frequ ently Obtain e dby bu rn ishing the sen sitized paper when dry.

( E .) THE PRINTING .

A fter th e paper has been sen sitized an d well dried it i s prin ted.

The n egat ive i s first laid in the prin ting fram e film side u p .

Th en th e paper is laid w ith th e sen si t ive yellow Side o n th e n egative

,an d th e fram e c losed. Before it i s placed in the light

,care

TH E I NR ING UP A N D D E V E LOPI NG . 1

sh ou ld be taken to see that th e paper l ies closely everywhere onth e n egat i ve

,otherw i se it w il l in parts be indi s t in c t

,an d t h e prin t

be u seless . For es t im at ing th e correc t exposu re a ph otom etersh ou ld be u sed, and I take as an exam pl e V ogel

’s Fig . 6 .

W hen beau t ifu l c lear n egat ives are u sed they shou ld be prin tedt o 14 to 16 degrees V ogel . Ob viou sly n o s t rict in s tru ct ion s c an b e

g iven for every case , an d it w ill be dependen t o n th e qual ity of th en egat ive an d t h e obj ect .If t h e n egative has t o be covered, 011 any oth er dodge u sed, th e

t im e of exposu re m u st of c ourse be arran ged acc ordin gly . A s a

g en eral gu ide it m ay be stated t h at th e de tail s of t h e pictu res hou ld appear brown and dis tin c t from th e gro und wh en th e prin th as been c orrectly exposed . Th i s exam in ation o f th e pic tu re m u stb e don e in a dark room ,

and on ly o ne side o f t h e prin ting fram esh ou ld be open ed , so t hat t h e prin t does n o t sh ift . If it i s overprin ted

,t h e pictu re develops badly, t h e l in es becom e broader, the

detail s di sappear in t h e deep sh adows , an d the ink adheres t o th eu n exposed parts . If

,o n th e c on trary ,

it i s u nder-prin ted,th e ink

does n o t adh ere w el l to t h e exposed places , an d w ash es off in

d evelopin g from th e fin e parts . Prac t i ce , as with all m an ip u l ation s ,is n ecessary, and therefore o n e m u st n o t be di sh earten ed by th e firs tfailu re .

(E ) THE INKING UP AND D E V E LOPING .

A s soon as o n e i s sati sfied that the exposure 1s su fficien t,th e

p rin t sh ou ld be taken from the fram e in the dark room . Then ext process i s inkin g up an d d evelopin g . Th is is e ffected invariou s ways ; the ink i s ei ther spread o n t h e dry prin t w ith a

v el vet rol ler or a thin developin g ink is u sed w i th a bru sh , or t h ebichrom ate i s firs t washed o u t and then the ink spread o n . Iprefer to ink u p the prin t w i th a velvet roller, on wh ich is t hedevelopin g ink , before wash ing . By this m ethod I ob tain be twee nink and gelat in e the soluble ch rom ium film . The prin t developsthen v ery qu ickly an d w ell . For this pu rpose it i s laid on a glas s

p late, a l itho ston e or any other flat su rface,a sm all qu an t ity of

good l itho t ran sfer ink i s di stribu ted o n an inking s ton e w i th an

o rdinary litho ro ller, and the velve t rol ler charged w ith th e ink

52 PHOTO-LI THOGRA PHY.

from th e ston e by rol ling it several t im es over t h e ston e . Th e

p rin t i s n ow roll ed u p wi th th e vel vet rol ler t il l it appears of agen eral grey t on e ; th e detail s of th e pict ure

,h owever

,are still

v is ible t h rough th e ink . With th i s first inking u p , too litt l erat h er th an t o o m u ch ink sh ou ld be u sed . W h en th e inking u pi s fin i sh ed , th e prin t sh ou ld be laid in cold water

,care bein g

t aken t h at n o air bell s form on th e su rface,and it is also advis

able to frequ en t ly t u rn t h e paper over on ce or t wice in t h e wat er.

A ft er t e n or fifteen m in u t es a ch ange w i l l be seen o n th e prin t,

th e exposed part s w ill be som ewh at m ore depressed th an th e n u

e xposed , wh ich will h ave swoll en t o som e ext en t in th e water.

Th e prin t i s n ow taken o u t of t h e wat er and spread o u t exposedS ide up o n a Sheet of glass , very c arefu lly avoiding folds

,an d

dried w it h blot t ing paper, and th e water which i s o n t h e back ofth e prin t i s rem oved by s tron g pressure o n th e prin t from th e

fron t .The prin t wh il st s til l dam p is again for a second t im e rolled

u p with t h e velvet roller,by w h ich m ean s t h e detai l s of t h e

drawi ng again t ake th e ink . From th e u n exposed part s th e inkn ow goes o n t o t h e roller, in exact ly t h e sam e way as in clean in gth e lit h o ston e , and t h ey appear covered n ow w ith a very fain tt on e . If t h e first rol ling u p was don e w ith t o o m u ch ink

,it w ill

be acc om pan ied by two disadvan tages . First ly,t h at t oo m u ch

ink w il l adh ere t o t h e detail s of th e drawing, an d there w il l bet h e danger th at in tran sferring th e sam e w ill appear thick, an d

secondly t h e t in t will n o t be so well rem oved from t h e unprin t edpart s

,wh ich w il l produ ce a difficu lt developm en t . I t is th erefore

advan t ageou s on ly t o give in th e secon d inking t h e prin t ed partsth e q u an t i ty of ink req u i site for t ran sfer .

A ft er being inked u p a secon d t im e th e prin t i s again placedfor a sh ort t im e in th e wat er, th en t aken o u t , spread o u t o n th e

sh eet of glass , an d n ow com pletely developed w ith a p ad or at u ft of c ot t on w ool . Th is i s effect ed by goin g over al l t h e prin tw i th ligh t pressu re and n o t t o o q u ickly w ith a circu l ar m ovem en t , t ill t h e draw ing appears qu it e clear an d clean o n a wh it eg11ou 11d .

'

I n t h i s Operat ion it i s advisable t o u se as m u ch wat eras possibl e , in order t o rem ove all t h e bich rom at e from t h e prin t

,

wh i ch m igh t be t roublesom e in th e subsequ en t operat ion s . Th e

w ash in g sh ou ld n o t th erefore be st opped t ill t h e u n exposed part shave lost all yellow tin ge and appear n early wh it e . If t h e

bich rom at e rem ain s in th e u n exposed parts , th e process con t in u esdu ring t h e drying of th e prin t t h ese places t h en becom e h arden ed

,

and l are freq u en t ly th e cau se of an u n sa tisfactory t ran sfer . On e

of the chief requ isites is, however, that too m u ch ink sh ou ld n o t be u sed

in in king up . The deve lop ed drawing shou ld n o t app ear de ep black,

bu t grey, ye t covered in a ll p laces . Th e developing ink c on t ain s solarge a q u an t ity of grease th at the least qu an t ity 1 s sufficien t t oform . the com bin ation previou sly described on th e ston e.

HUSN I R’S PHOT O-L I TH OG R A PH I C PA P E R . 53

The developed prin t is freed from al l adh erin g w ater by pressu re w i th h alf—«dam p blot t in g-paper

,and th en fast en ed on t o a

board w ith drawin g pin s t o c om pletely dry .

T h e room w h ere t h e developm en t i s c arried on shou ld be w ellven t ilated

,an d n o t be h eat ed t o o m u ch

,as th e lat t er m akes th e

w ork m ore di fficu lt . T h e dryin g ou gh t n o t t o be forced and

shou ld be allowed t o t ake place spon t an eou sly at th e ordin arytem peratu re of th e room .

For t ran sfer t o zin c an d for sen di ng photo-li th ographic prin tsit i s advisable t o bath e t h em in a 10 per cen t . solu t ion of alum for

abou t five m in u t es , so th at th e gel at in e film i s h arden ed . Whenth e prin t s are t o be u sed or t o be tran sferred t o st on e im m ediat elythis t reatm en t m ay be om it ted w ith ou t h arm .

2 . V A R IOUS OTH E R PHOTO-LI THOGRA PHIO PA PE RS.

Th e paper described above i s a pu re gelat in e paper, an d

al t h ough t h i s h as proved in practice to be sat isfac t ory for allwork t h at m ay arise, s t i l l I w il l desc ribe som e oth er papers,which h ave been also u sed in pract ice w it h good resu lt s

,an d for

those wh o do n o t care t o prepare th eir own paper t h ey have th eadvan t age th at th ey m ay be obt ain ed com m erc ially .

A lbu m en was u sed firs t in stead of gel at in e an d ren dered se n

sitive by th e addit ion of a ch rom ium sal t . Th is paper h ad th e disadvan tage th at it cou ld n o t be kept

,and on ly su ffic ien t paper an d

album en solu t ion for on e day’s w ork cou ld be prepared . A m u ch

great er di sadvan t age , howev er, was t h at in devel opin g,th e

album en film was rubbed o ff w ith th e p ad, an d th e paper w as

m ore or less rubbed u p . A t in t was produ ced throu gh t h is

wh ich t ran sferred t o th e ston e,an d thu s gave rise t o con siderable

trou blesom e an d t ediou s ret ou ch in g. Th i s i s n o t t h e case,h ow ever

,

with th e gelat in e coat in g, which is com parat ively m ore resistan t .

(A .) HUSNIK’S PHOTO-LITHOGRA PHIO PA PE R .

Prof. Hu sn ik has com bin ed th ese two p ro c e se ss for t h e produ ction of h is papers , as h e gives a coatin g of albu m en t o a papercoated w ith gelat in e , which shou ld be ren dered sen sit i ve w itham m on ium bich rom ate . By this m ean s i s

,o n t h e on e h and

, t h e

rubbin g u p of the paper preven ted an d dam age t o t h e im age n o teasily possibl e ; o n th e ot h er han d, th e developm en t t akes placevery qu ickly, as th e album en film dissolves an d c an be easilyrem oved w ith th e greasy ink . Hu sn ik spec i ally con t en ds t h atw ith t h e u se of th ese papers he obtain s extraordin arily sh arpim ages w ith ou t any t in t . T h e sheets thu s prepared w i l l on ly keep

,

how ever, o n e or t wo days,and th is in con ven i en t Operat ion h as t o

be repeat ed every t im e before u sin g th e paper . Th i s applies alsot o t h e album en solu t ion ,

so Hu sn ik h as com e t o th e con clu sion th atit is be tt er and m ore pract ical t o u se plain gelat in e paper ; b ut

54 PHOTO-L I THOGRA PHY.

when trou ble , tim e, and cost are n o t of su ch great con sideration ,

th en i t I S bet ter [10 u se t h e paper w ith t h e com pou nd coat ing,as it

en ables l ess experien ced operators t o produ ce good work .

T h e pap er m ore recen t ly produced by Hu sn ik I s a p ure ,DG elatin e

paper,wh ich 1s rendered sen si t ive to light I n

A m m on i um bichrom ate 1 partW at er 15 partsA lcohol (ordin ary) 4

A s m u ch am m on i a is added to t h e bich rom at e solu tion as w il l c onvert th e reddish colou r in to yellow

, and t h e bath sm ell s ofam m on ia. The bathing of t h e paper m u s t be don e as qu ickly as

possib l e , an d t h e sh eet sh ou ld on ly be drawn through th e solu t ion .

Th e exposu re for thi s paper i s from o n e t o th ree m in u tes in th esu n ,

or from t e n t o th irty m in u tes in diffu sed light .T h e inking up of t h e prin t shou ld be don e wi th a gre asy tran sfer

ink,t o w h ich o n e - si xt h part of wax has been added, and t h e w h ole

disso l ved in t u rpen t in e t o t h e con sis ten ce of oil . T h e prin t isinked u p w ith t nis th in ink

, and th en gon e over with a p ad of

ot ton wool t i ll it h as t aken an even gray t in t .

Wh en t h e t urpen t in e h as evaporat ed t h e prin t i s laid in coldwater

,and , aft er abou t t e n m i n u tes , developed w ith a soft th ick

p ad w i th a con t in u ou s circu lar m ovem en t and qu ite ligh t pressu re .

A ft er developm en t al l adh ering water is rem oved from t h e prin tw ith dam p blot t ing-paper

,and the tran sfer c an be effected after

from fift een t o tw en ty m inu tes .Hu sn ik ,

however,did n o t rest

,an d soon prepared a s ti ll better

p aper, wh ich i s kn own - at t h e presen t t im e com m ercially asHu sn ik

’s A u to typic P aper . He produ c es th i s paper in large

qu an t i t ie s , the c oat ing of th e gelat in e being effect ed by m achines ,which certain ly t ends t o en su re equ al ity .

Hu sn ik fou n d t h at by th e u se of less con cen trated bichrom atebath s th e fin e l in es w ere stronger af ter prin tin g th an from th e

n at u re of th e n egative th ey sh ou ld be . From o n e an d t h e sam e

n egat ive t h ere w as Ob tain ed b y th e u se of a bich rom at e bath of

1 t 100 a rel ief five t im es as broad as wh en a b ath of 1 : 15 was u sedt o se n sitize t h e paper . Th i s h e ascribes to th e colou r of th e

gel at in e bein g less , so that m ore rays of light pen e trat ed to t h esu rface of the paper, from wh ich it wou ld be again reflected , ande very poin t or lin e again reprodu c ed , which m u st obviou sly lead t oan in crease of th e S i ze of th e sam e ; o n t h e oth er hand, w ithstrongly ch rom at e d paper

,t h e rays of ligh t wou ld n o t oii ly b e

absorbed by th e in ten se y ell ow colou r of th e chrom ium salt, b u t

stil l m ore by the brown t on e form ed im m ediat ely after prin t ing,wh ich m akes a reflection im possible . W ith au t otype n egativesth i s i s specially striking

,as w i th w eakly-ch rom at e d paper black

sh adows w ith ou t det ail s occu r, becau se h ere th e qu an ti ty of ligh tis di stribu ted by reflect ion over th e fin e poin ts, an d they will

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6 PHOTO-LI THOGRA PH Y.

A m m on i um bichrom at e ough t n o t t o be u sed . The bath wou l dth en becom e cloudy im m ediat ely, and both bath an d paper m adeu seless .

“Th en sen sit ized th e paper c an be kept from eigh t t o t e n daysw ith ou t losing its good q u alit ies .

W i th th i s a tran sfer ink i s supplied in tubes, wh ich m u st b e

m ixed w it h an eq u al vol um e of t u rpen t in e and ben zin e,so that

it becom es qu it e flu id . Th e print, wh en it i s t aken from t h e fram e

,

is fas t en ed o n a board w i th draw ing pi n s , and w i th a‘

fin e cam el’sh air brush coat ed w ith th i s fl u id ink as evenly as possibl e

, and j u stso m u c h t h at a l igh t grey ton e i s form ed o n th e prin t . Th is paperm u st n o t be inked up w i th a roller. A s soon as th e t u rp en tin eand ben zin e h ave evaporated th e prin t i s laid in cold water

,and

aft er abou t t e n m in u t es developed w ith a c le an tu ft of cotton wool .

T h e prin t does n o t sh ow a s trong relief ; th e developm ent t akesplac e qu i ckly an d regu larly . Th e ink

,in spite of its being so t h i n

,

i s v ery greasy, so th at on ly a very ligh t sk in is n ecessary for t h esubseq u en t t ran sfer. Th e t in t produced by a n egat ive slight ly t o oth in c an n ot be easily rem oved .

Th e oth er operat ion s are t h e sam e as for the other photo- l ithograph ic papers .

Fran z’s ph oto-l ithographic paper i s characterized, as al ready

m en t ion ed, by giving extraordinarily sharp clean t ran fe rs,w h i ch

,

indeed,m ay be du e t o th e u se of th e very th in liqu id greasy ink . It

is,th erefore

,especial ly t o be com m ended for very fin e work .

(a.) A LBE RT’S PHOTO-LITHOGRA PHIC PA PE R.

A u gu st A lbert’s i s also a very good photo-l i thographic paper .

It can be obtain ed com m ercially in two qu al it ies , Ph oto -l ith ograph ic paper ”

an d“ A u t otypic high glaze paper . Th i s h as

been test ed in th e K .K . Leh r-un d V ersu chsan st alt fur P h otographie u n d R ep rodu c t ion sverfah re n in V ien n a, an d h as receiveda cert ificate of excel len ce . The high glaze pap er h as a preparedfilm of several coatings ; the developed prin t s when dry keep th ehigh glaze .

Th e sen sit izin g bath con sists of

W ater 16 parts by w eightPotassium bich rom ate 1 partA lcohol (ordin ary) 4 parts

and to thi s so m u ch am m on ia i s added as w ill con vert the reddishcol ou r in to a ligh t yellow ; a sm all excess of am m on ia does n oharm . The bich rom at e bath Shou ld n o t h ave a lower tem peratu reth an 1 5

° R ,or el se th e solu tion cann ot pen etrate t h e film

su fficien t ly, w h ich resu lt s in a defective developm en t . Th e du ration of sen sitizing -i s from fou r t o eigh t m in u t es , t ill t h e paper is

q u i te soft and dam ped through . I t i s preferable t o sen sit ize t o olong rath er than t o o sh ort.

T RE A TM E NT OF TH E PRINT A N D TH E PLA T E . I

The paper sh ou l d be squ eegeed on to plate-glass , as alreadydescribed

,and a llowed to dry spon t an eou s ly. The paper w h en

stripped from th e plat e-glass h h ows a beau t ifu l high glaze, an d c an

be kept fit for u se for twen ty-fou r hou rs . When t h e paper i s olderit can still be u sed, b u t t h e dev elopm en t is m ore difficu l t , an d it isbet t er t o avoid this for fin e draw in gs or au t otypes .A lbert does n o t recom m en d a ph otom et er to be u sed wh en

p rin tm g this paper, b u t by exam in at ion of the prin t t o j u dgewhen t h i s i s c orrect . T h e im age sh ou ld have a brown ton e

,and

be easily dl st ingu ish e d by th e e y e .from the grou n d . Over-p rl n tin g is di sadvan t ageou s, as the lin es an d poin t s becom e broader, th eprin t s develop badly

,th e tin t adh eres firm ly t o th e grou n d, and

th e detail s in th e deepest shadows are lost .

T h e inking an d developin g c an be don e by an y of th e kn own

processes wh ich is though t desirable. The ch ief th in g is th at t o om u ch ink m u st n o t be u sed in the first inkin g u p an y in t e n sifica

t ion re qu l re d m ay be efi e c t e d w ith a secon d coat ing. Th i s i s,

especially for fin e draw in gs an d au totypes,very im port an t

,wh i l st

for coarser work also on ce inking is su fficien t . The prin t s are t h enplaced in cold w at er, and aft er su fficien t wash ing sh ou ld bedeveloped w ith a soft p ad or p ad of wool , with which an y t in t c anbe very easily rem oved from any parts which shou ld rem ain wh it e .

3 . THE PHOTO-LITHOGRA PH IC TRANSFE R.

(A ) TRE ATME NT or THE PHOTO-Ll THOGRA PHIC PRINT AND THE PLATE .

Th e tran sfer from the bich rom ated gelatin e paper requ iresgen erally, as regard s treatm en t an d choice of t h e m at erial , great ercare on t h e part of th e prin t er th an an ordin ary t ran sfer

,an d t h i s

in creases in t ran sferrin g fin e draw in gs or au totypes o n t o ston e .I n th e first place th e good qu ality of th e ston e shou ld be looked

to . For ord1n ary or coarsely drawn subj ec ts t h i s i s of less im port an ce

,b u t for ,

fin e draw ings an d au totypes it i s of the highestim portan ce . Fu rther

,accu racy an d clean lin ess are al l im portan t

,

withou t wh ich su ccessfu l w ork is im possible . On t h e other h and,

a t ran sfer c an hardly fail if it be accurately an d correct ly perform ed.

W h en the prin t com es from the developin g bath,and has been

w el l washed so that every t race of bichrom at e is rem oved, it shou ldbe freed from excess of wat er between bl ot t in g-paper . I t sh ou ldt hen be dried in a n o t t o o warm plac e free from du st t il l th egelat in e has com plet ely se t an d feel s absolu tely dry . T h e reliefw ill have n ew again disappeared , an d th e black an d whit e placeslie l n the sam e plan e. I t i s best dried by pin n in g it to a boardwith draw in g pin s , an d then se t u p in a dry

“place .

I n th e m eanwhil e t h e t ran sfer st on e shou ld be prepared , whichm u st be absolu t ely fau ltless . Ju st before t h e tran sfer it sh ou ldb e dry polish ed w ith pum i ce s tone , and then w ell du st ed w i th a

5 8 P I IOTO-L I THOG RA PHY.

clo th . The slightest g1 ain w il l give a Spot in a fin e ton e .

Obviou sly t h e st on e m u s t be wel l ground so th at n e it h e 1 an yspot s n 0 1 lin es of an earl ier t ran sfer c an appear. W i th an opendraw in g this can be c or1 e c ted , b u t n o t w ith an au totype in su cha case t h e sh ortes t way i s to m ake a n ew pr1u t and a n ew tran sferTh e prin t is first w iped over o n th e back w ith a dam p cloth

, and

then l aid o n dam p blotting-paper. A fter abou t five m in u tes th eprin t i s t reated a second t im e with a dam p cloth

, an d then laidbetween dam p blott in g-pape1 . I t 1s n o t advisable to lay t h e prin tbe tween ordin a1 y dam p blot t ing paper

,as th e gelatin e becom es .

som ewh at sticky,an d wou ld at tract particles from the rough

paper.

T h e degree of dam pn ess which is n ecessary for tran sfer m ay b e

ju dged in t h at the prin t m u s t feel soft,b u t t h e gelat in e film ought

n o t t o be very st icky . A ny fu rther preparation of t h e prin t beforetran sferring t o th e ston e i s n o t n ecessary. Th e prin t is laid o n th es ton e

,over it a dry sh eet , an d th en t h e cover

,an d th en drawn

through t h e first t im e w i th ligh t pressu re .

I n order to prove whether t h e tran sfer h as taken w ell a corn erm ay be l ifted u p . A ll the ink wh ich was on t h e prin t m u st bet ran sferred t o t h e ston e, an d th en th e tran sfer has been com pletedin th e correct w ay . Th e prin t i s n ow pu lled o ff th e ston e and th etran sfer m ade ready

,l ike any oth er.

W i th th i s m eth od of treatm en t t h e prin t w il l strip easily, wh ichi s n o t t h e case if it was n o t w ell dried after t h e developin g bat ha m u ch sh arper an d clean er tran sfer w ill al so en su e . If th e prin twas t o o dam p a fu zzy

,broken -down tran sfer w ill be obtain ed ,

bec au se the gelatin e, which has becom e too soft , w i ll be broken

down .

I w il l al so m en tion that it is n o t advisabl e to treat fin e draw ingsor au to types w ith th e Tubbin g-u p p ad . It 1 8 bet ter to go o ve r t h et ran sfer w ith the roller, an d t h e ton es are kept clean er. T h e s ton eis t h en gum m ed

,placed on o n e side

,an d allowed to s tan d som e

hou rs before being e tch ed .

For t ran sferring to z in c plates which are to be etch ed or to beprin ted from

,t h e bich rom ated gelatin e prin t shou ld be bathed in a

t e n per cen t . sol u t ion of al um ,allowed to dry , an d th en

,as

previou sly described, dam p ed, an d th en t ran sferred u n der th e

sam e con dition s as to st on e .

I t on ly rem ain s to m en tion that th e ston e or z in c plat e sh ou ldn o t be too cold .

(a.) FA ILUR E S IN TH E PHOTO-LITHOGRA PH IC T RANe Rs.

Th e fai lu res or fau l ts wh ich are m e t w ith i n ph oto-l ithographictran sfc i m ay be cau sed by variou s th ings .T h e squ ash ing down 1 are ly h app e n s

c3

w ith photo l itho t i an sfe r,

becau se a good pho to l1t l1o o '

1 ap h 1c paper vill bear a con siderable

FA I LUR E S I N TH E TRANSF E RS . 59

am oun t of dam pn ess . When ,h owever

,it occu rs it m ay be assum ed

th at ei th er too Stron g pressu re or in su fficien t care in t h e sett ing ofth e st on e i s t h e cau se . Mu ch m ore freq u en tly i t happen s th atsom e part s of t h e print do n o t t ran sfer at all

,or on ly in a defec t ive

m ann er . T h e ch ief reason of th is i s th at the prin t was in su ffici en tlydam ped . Th i s frequen tly happ en s if ordin ary or gravu re prin t sare to be t ran sferred wi th ph oto-l ith ograph ic prin t s . I f th e prin t erencloses th e im p ression o n th e ordinary t ran sfer paper an d th e

ph oto-l ithograph i c t oge th er in the sam e dam p sh ee t , an d if hees tim at es t h e degree of dam pn ess from th e gravure prin t

,the

ph oto- li tho paper w ill be in su ffici en tly dam ped and a good tran sferw ill n o t b e obtain ed from th e latt er. If, h owever, h e wai ts t il l th eph oto -l i th o paper i s dam p en ough ,

th e oth er im pression s w il l be toodam p an d w ill sq uash o u t in t ran sfer . Fo r su c h work t h e prin to n ordi nary tran s fer paper an d th e ph o to-l ithograph ic prin t shou ldbe k ept separate, so th at th e differen t dam pn es s requ i site for eachcan be regu l ated .

A n oth er case which frequ en tly h appen s i s that th e prin t i scon t am in ated w ith parti cles of du st or other foreign subs tan ces .These m ay be flyin g abou t in the air or b e o n th e s ton e

,th e rol ler

,

or th e dam ping paper. Th rou gh th i s m any tran sfers of fin e

drawi ngs are ren dered u seless . P erfect clean lin ess of th e u t en silsand t h e u se of th e correct on es , com bin ed w ith a dryin g-room forth e prin t absolu tely free from du st , are absolu tely essen t ial forfau l tl ess work .

T h e c om posit ion of the ink , especial ly if i t was too hard,m ay

give rise t o b ad tran sfers .Ph oto - l ithograph ic papers

,which are prepared w ith very h ard

gel at in e

,m u st be l aid before t ran sferring in lukewarm w at er . By

t h i s m ean s th e h ard gel atin e becom es rat h er st icky,an d t h e greasy

ink t ran sfers m u ch be tter . E ven those poin ts wh ich in developin ghave tak en u p l it t l e ink , an d appear grey, tran sfer com ple t ely t o

the ston e an d adhere firm ly.

60 PHOTO-LI THOGRA PHY.

CHA PTE R IV .

PHOTO-LITHOGRA PI IY BY D I R E CT PR INT ING ON TO STONE OR Z INC.

THE processes of ph oto-lith ograph y previou sly described are basedupon th e prin t ing o n t o bi c h rom ated gelat i n e or albu m en paperdevelopm en t w it h a greasy ink an d subseq u en t t ran sferen ce oft h e greasy prin t t o plat e or s ton e . A process m ay al so be u sed inw h ic h t h e s ton e or pl ate i s pri n ted o n direc t . Th ere are in th i svariou s m eth ods

,o f whi ch t he principal are prin t i ng 011 t o ligh t

sen sit i ve asphal t , or an organ ic su b stance, gelat in e or album en ,in

c om bin at ion w ith a bich rom at e salt . Th e reason i s th e highsen sitiven ess, wh ich is possible, of t h e subs tan ces u sed.

1 . THE A SPHA LT PROC E SS .

(A .) THE L IGHT-S E NSITI V E A SPHALT .

Ligh t-sen siti ve , o r se -call ed Syrian , asph alt, whi ch is preparedfor ph oto-li th ograph ic and ph ot o-zin cograph i c pu rposes

, c an beo b tain ed from variou s firm s wh o deal in ph otograph i c goods

,an d

o n e h as on ly t o dissolve t h e sam e accordin g t o th e p i e sc rib ed

d irect ion s . This kind of asph al t is , h owever, n o t very sen sit i ve,and in u se m u st be prin t ed for som e con siderable t im e . If

,th ere

fore,an asphalt of greater sen sit iven ess is desired 1t i s n o t su ffi

c i en t t o m erely di ssolve Syrian asph alt, b ut it m u s t u ndergo a prelim in ary preparat ion .

On ly that part of the asphalt i s sen sitive or u seable for photolith ograph i c w ork which does n o t dissolve in eth er. T h e in se n si

tive part m u st , th erefore, be separated o u t, which i s don e by

fin ely powdering th e asph al t, sift ing it th rou gh a fin e si eve, an d

t h en t reat ing it w ith eth er . A ll th at is solu ble in e th er goes 1n t osolu tion th e m are which i s n o t solu ble in et h er i s th en dissolvedin ben zole an d u sed as wan ted .

(a .) HUSNIK’S PROCE SS.

Professor Hu sn ik h as im proved th i s process in so far that hedoes n o t di ssolve th e asphal t powder in eth er, as , according t o h is

view ,a com plet e solu t ion of al l th e in sen sitive portion i s n o t

attain ed by t h i s process, b u t he di ssol ves coarse asph al t powdercom pl etely in rec t ified spirit of tu rpen tin e t o the con sisten c e of am oderat ely-th ick syru py m ass , u n ti l n o hard part ic l es or a re sidu e

are con t ain ed in th e solu tion . To th i s v i scou s asphalt sol u t ion a

plen t ifu l qu an t ity of eth er i s added gradu ally, and w ith con stan tstirring, and a big flask sh ou ld be u sed for t h i s pu rpose . A fter as ufficien t qu an ti ty of eth er has been added a pi tch -l ike deposi t

V A LE NTA’S P ROCE SS . 1

separates ou t at th e bottom . I n order to test whether there isstill any ligh t -se n sit ive asph alt 1n th e su pern at an t liqu or a sm allqu an t i ty i s pou red into a glas s an d m ixed w ith eth er, wh en if a

precipit ate en su es m ore eth er m u st be added t o th e big flask .

A ft er st an din g for abou t twen ty-fou r h ou rs t h e eth er c on tain sal l soluble in sen sitive con stitu en t s of t h e asph alt ; the pit ch l ikeres idu e in the flask

,after pou rin g Off the solu t ion , i s again t reat ed

with eth er, so that all tu rpen tin e is extract ed an d an y stray in sensit ive particles are di ssolved . The pit chy residu e i s n ow rem ovedfrom th e flask an d allowed to stan d in a porcelain dish in a warmplace

, w ith frequ en t st irring, till it i s qu ite freed from ether, an dh as form ed a h ard, brittl e, black sh in in g substan ce , which can b e

easily broken u p in to powder w ith th e han d . This produ ct i s n owth e ligh t-sen sit ive asph alt, wh ich i s dis solved for u se in

‘

an h ydrou s ben zole . A S ben zole i s on ly t o be obtain ed an h ydrou s w ithdifficul ty

,some ch l oroform i s added to th e solu t ion i n orde r t o

preven t th e ru nn ing togeth er in drying, wh en ce t h e film w ou ldbecom e u n equ al and pat chy .

Th e coating of th e st on e or plate w ith the asph alt film i s verysim ple ; it shou ld be placed horizon tal , an d then wh irled rapidlyon a wh i1 ler .

P 1 in t in g u nde i a clear n egative takes from a qu arter to half anhou i i n d 1i e c t su n ligh t .T h e picture i s developed w ith tu rpen tin e .

(b .) V A LE NTA’S PROCE SS.

V alen ta recom m en ds for photo-lithography asphalt which h asbeen su lph u rized by th e w e t process

,as it possesses a con siderably

h igh er ligh t- sen sit iven ess than th at which is n o t su lp h u rize dfif

The process is as fo llow s z— IOOg . of raw Syrian asph alt areboiled in a retort w ith an equ al qu an tity of raw pseu do- cum en e

,

wh ich has th e form u l a C 6H3(CH3)3 , an d a boil in g-poin t of abou t1 70°C , w ith 12 g. of flowers of su lph u r

,wh ich sh ou ld h ave been

previou sly di ssolved in th e pseu do -cum en e . Wh en aft er abou tth ree or fou r hou rs’ boilin g the evolu t ion of su lph urett edhydrogen h as ceased, the pseu do-cum en e is di st ill ed off an d th e

black pi tch y~residu e dissolved in ben zole in t h e proportion Of

an d u sed for th e preparation of th e plat e or s ton e .

Th e su lphu rized asphalt prepared in this way is alm ost in solu blein eth er

,b u t dissolves fairly readily in ben zole

,t olu en e

,xylen e

,

m en e,an d t u r

,pen t in e and is very sen sit ive t o ligh t .

W i th th is asph alt good prin t s are obt ain ed even in b ad,

c lou dy w e ath e i . For u se fou r part s of t h e su lph u rized asph altare di ssolved in 100 parts Of ben zole , th e solu t ion filtered an d

dilu t ed t i ll a th in film o n a zin c plat e sliows a golden yellow colou r .

E xposu re of th e asph alt solu t ion in an open flask for from h alf t oo n e h ou r in su n ligh t i s advisable .

For developing t h e asph al t im age rect ified o il of tu rpen t in e freeE der

’s Jah rbu ch der Ph o tograph ie , 1 892, p . 24 1 .

6 2 PHOTO- LI T HOG RA PH Y .

from acid is u sed ; th e best is Fren ch or A u s trian . T h e developm en t m ay be accelerat ed b y addi ng Hungarian or R u ssian t urpent in e , wh i c h ,

h owever, at tack th e asphalt im age ; it c an be res train edby t h e addi t ion of ligroin , ben zin e , or wood oil to th e tu rpen t ine.Z in c plates are best developed in a dish

,s tones by m ak ing a wax

m argin rou nd t h e drawi ng . The oil of tu rpen tin e is poured o n

a nd rocked t o and fro . Ru bb ing w ith a p ad of cotton wool , etc .,

sh ou ld b e avoided . A fter developm ent th e plat e sh ould be wellwash ed u nder a s tream of water, and before gumm i ng

,th e plat es

shou ld be exposed fo r som e t im e to light, as t h i s m akes t h e g1 o undm ore resis tan t to th e e tch ing.

(E ) COA l‘

ING T E E STON E S.

Th e ston e or zin c plate i s n e w coa ted w ith o n e of the aboved esc ribed asp hal t sol u tion s , or w it h th e following

A sph alt 20 g.Ch loroform 300

Benzol e 100

Oil of Lavender 20 drops .

Th e solu tion m u st be th in,so th at it flows over th e ston e w ell

a nd does n o t form u n eq ually-covered patch es .Th e subseq u en t m an ipu lation s m u st b e condu cted in th e dark.

Th e s ton e which i s to be u sed m u st be wel l ground,and polish ed

w ith dry pum ice stone , w ell du sted, and be absolu t ely flat . Itou gh t n o t t o have any depress ion s

,as t h e n egative wou ld n o t lie

‘ in con tact there . The places w ou ld n o t prin t sh arp,an d therefore

a b ad resu lt wou ld be obtain ed .

T h e n ecessary qu an t i ty of t h e solu t ion i s n ow pou red in to th em iddl e of a well-polish ed s tone

,and d istribu ted as even ly “ as

p ossibl e by rocking backwards and forwards . When th oroughlyd istribu ted th e stone sh ou ld be placed o n t h e whirler and kept forsom e tim e in m otion . The asphalt solu tion m u st be as thin aspossible

,so th at it appears yellowish-brown and th e colou r of th e

s ton e appears th rough it . If the ston e is on ly covered all over th e‘

fi lm c an be very thin ; on th e other han d, if it is too th ick it w illn o t prin t through, an d w il l develop badly, as too m u ch of the

.a sphalt w ill dissol ve . If z in c pl ates are u sed for prin ting theysh ou ld be prepared as previou sly described o n p . 6 . Zin c platesfor deep etch ing m u st be well grou n d and w el l poli shed

, and‘ o ught n o t to repel water. The z inc plates are coated the sam e as

t h e s ton e .

(C.) PRINTING .

“Then th e film i s absolu tely dry , which w ill be in abou t fifteenm in u tes , prin ting m ay be proceeded with . For th i s purpose th en egat ive is either laid o n to the asphalted ston e , film side down ,:an d pressed down wi th screw bands , or it i s laid, the glass downwards , in a spec ially-con stru c ted and very strongly-bu il t prin tingfram e, which is provided with a sh eet of plat e glass, and t h e

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64: PHOTO-L I T HOG R A PHY.

e tchin g solu t ion of tin ctu re of galls or gallic acid and ph osph oricacid

,and inked u p .

Prin t s o n zin c plat es for deep etchin g are gum m ed after developing, an d if th e asph al t film is perfect w ith ou t rubbing u p w ith a

p ad, wh ich th icken s th e drawin g, etched for som e m in u tes in verydilu t e n i tric acid .

Many l ith ograph ers are accu stom ed, an d in deed it is n ecessaryw ith som e t ran sfers

,t o rub t h e prin ts u p w ith greasy in k .

‘

The process i s as fo llow s z— Crre asy t ran sfer ink i s di lu t ed w i thsom e t u rpen t in e, and after th e st on e h as been gum m ed and allowedt o dry , t h en washed, th e drawin g is w iped over w ith a soft p adw i th t h i s di lu t e in k

,wh en th e in k adh eres to t h e drawing

,

strength en s it , and if great care i s n o t t aken,th icken s it also .

W i th asph alt prin t s th is i s absolu t ely u seless,and for o th er direct

prin t s,as w ell also as for good c h rom at ed gelat in e prin t s , in m ost

cases u nn ec essary . T h e exposed asphalt com bin es so in t im at elyw ith th e ston e th at st rength en ing w ith a greasy ink i s q u i t e u nn ecessary

,i s in deed absolu tely pu rposel ess , as th e ink c an n ei th er

pen etrat e th e h ard asph al t film n or com bi n e wi th it . T h e film ofasphalt alon e i s so resi st an t t o every et ch in g solu t ion th at it i s forthis reason absolu tely u seless to st rengt h en it .

2 . OTHE R PROC E SSE S .

Besides t h e asph al t o th er m ixtu res of oth er light-sen si tivesubst an ces m ay be u sed for direct prin t ing, an d t h ese are m ost lyorgan ic subst an ces in com bin at ion w ith a ch rom ium salt

, an d

possess al so a great er sen sit iven ess to ligh t th an asphal t .

Th e solu t ion s wh ich have been special ly u sed in ou r establishm en t con sist of

(A ). A lbum en 5 g.

A m m on iu m bich rom ate 3

D is t illed w ater 500

A m m on ia 15 -20 drops

(B). Ch loroform 250 g .

Ben zin e 50

A lc oh ol 20

Mast ic 2

A n i lin e re d 2

Solu t ion A . i s s tron gly sen sit ive t o l ight, and i s u sed for coat ing ,

t h e st on e or zin c plate ; w it h solu t ion B t h e ston e 1 s c oat ed beforedeveloping . Th e detail s of th e process are as follows

(A .) COA T1NG THE PLATE S.

A fter th e st on e h as been carefu l ly pol ish ed an d w ell du st ed itsh ou ld be firs t flow ed over wi th di st ill ed water

,in order t o

in crease th e possibil i ty of spreadin g th e sen sit ive solu tion . W h ent h e w at er h as ru n off, t h e st on e wh il s t s t ill dam p sh ou ld be flowedover w ith sol u t ion A ,

an d care sh ou ld,

be t aken th at th e sam e iseven ly dis tribu t ed an d that n o bubbles form . Th e ston e sh ou ld b e

FURTH E R M A N I PULAT I ONS . 65

plac ed im m ediately o n th e wh irler and rotated til l the solu tion isdry . Obviou sly a th ick film m u st be avoided, as in su ch a casethe prin t w ou ld n o t adh ere t o th e st on e .

If a zin c plate be u sed it m u st be w el l prepared an d be ren deredfree from grease . To prove th i s th e plate is flowed over w ithdist il led water, an d wh en th i s Spreads equ ally all over an d i s n o trepelled from an y part, th e solu t ion c an be poured on . If, h owever

,th e plat e does n o t w illingly t ake water everywhere , it m u st

be again clean ed or poli sh ed . The oth er operation s are t h e sam eas for th e ston e .

(B .) THE PRINTI N G .

Wh en the film i s qu ite dry , prin tin g m ay be proceeded w i th .

Th e du rat ion of prin t ing depen ds Obviou sly also here again on two

im portan t factors— the qu ality of th e n egat ive an d th e stren gth oft h e light . U nder a good n egat i ve w ith absolu te bare glass in thelin es of the drawing I prin t t o abou t 10° V ogel , for exam ple

I n direct Su n l ight (m iddl e of A pril , 1 1 a m .) 2 m in .

I n t h e shade 5

I n electric are light (3000 c .p ., at a di stan ce of50 cm .

2 20 in s . w i thou t reflector) 25

The pictu re i s fain tly visib l e . If t h e n egat ive was too thin,or if

it be over-prin ted, th e im age develops badly or n o t at all . W ithu n der-prin t in g t h e film w ash es righ t aw ay.

Im m ediately after prin t ing t h e stone or plate i s coated w ithsolu t i on B

,which i s distribu t ed as even ly as possibl e by rockin g

backw ards an d forwards . It is n o t n ecessary,however

,to ob tain

even distribu t ion w ith a whirler. The whole of the coated su rfacebecom es deep v iolet .

(C.) THE D E V E LOPME NT .

When solu tion B has becom e com pletely dry ,th e ston e i s placed

in a su itable v essel with pu re w at er . A fter abou t five m inu t es t h eplaces n o t affect ed by light dissolve if th e ston e is rocked

,an d it

i s on ly n ecessary t o go ov er the draw in g w ith a p ad of cot ton w oolto cl ean the sam e c om pletely . Th e draw in g n ow appears a deepviolet on a bright grou n d . The developm en t i s con t in u ed w i th ou trubbin g strongly w ith th e p ad— wh ich m ight ru b u p t h e draw ing—t ill al l th e detai ls of the draw in g appe ar clear an d di st in ct .This especially applies to the detail s in t h e deep sh adows .

( D .) FURTH E R MANIPULA TIONS

When th e ston e or plate i s correctly developed, which can b e

easily told, it sh ou ld be wel l rin sed an d again exposed to m akethe film adhere firm ly .

’

It shou ld then be g um m ed an d treatedas previou sly described in the asphalt process . Th e “

ru b b ih gup of the ston e or plate i s n o t n ecessary it i s bet t er to rol l u pthe draw in g with an ink roller . Zin c plates for deep et ching c an

be lightly et ched, then du sted w ith fin e asphalt of resin powder,

heated an d then further e tched .

PHOTO-L I THOGRA PHY.

R . J. Sachers, of Toron to,Can ada

,published a sen sitive s olu

tion which has t h e foll owing c om posit ion :

D istilled water 1150 partsFish glue 50

A m m on ium bichrom ate .2

A m m on ia 2

Ch rom ic -acid .1 partThis solu t ion i s brown

,n o t very t ran sparen t , w ith an ol ive green

t inge , an d‘

m u st stand and set t l e at leas t tw elve h ou rs before itc an be decan ted , filt e red,

'

and u sed . T h e t im e of exposu re is abou tD irect sun ligh t 2-5 m inut esD iffu sed ligh t 12-15

E lectric are l ight (3000 c .p .,50 cm .) 30

The im age appears a bright brown o n t h e golden yel low groun d‘

Of th e plat e . T h e developm en t i s effect ed in an aq ueou s sol u t ion ofm ethyl violet

,when th e im age assum es a b eau tifu l blu e violet colou r.

The developed im ag e i s h arden ed w ith alc ohol . Th e resu lts byth i s m ethod are very good

,and although th is is recom m ended for

half~t on e et ching, it i s al so su itable for ph oto-l ith ograph y.

E xcellen t resu lt s also attend t h e sen s itive Marin e glu e solutio n ,

" prepared by A . H e b e n sp e rge r, of Mu n ich ,t o wh ich a second

solu t ion called Ch lo rogu t t-losu ng

‘ ” i s added .

‘

T h e sen siti ven esst o l ight i s very high , and the t reatm en t abou t th e sam e as w itht h e first described substan ce . Th e “

m arin e glu e solu tion ”

c o n

si s ts of album en , bich rom ate of soda and amm on i a . Th e dye

solu tion of V ictori a blu e di ssol ved in ben zin e .

Th e process publ ish ed by W aterhou se con sists of coating *

a

prepared zin c pl ate w i th a thin c h rom at e d solution,and th en

dryin g in a few m in u t es w ith a gen tle heat

(A .) A rrowrootPotassium bichrom ateWater

(B .) A lumWat er

For u se m ix‘

Solu tion A 40 partsPotassium 5

Solu t ion B 15

This is prin ted u nder a '

re ve rse d n egative for abou t six m inu tesin th e su n . The plate .i s then laid for abou t half an hou r in c oldwater in order t o rem ove t h e .chrom ium sal t s , an d th en clean sedfrom '

all soluble parts w ith a pad, and afte r well wash in g set u p todry .

It i s th en inked up w ith tran sfer ink, and after abou tfifteen m in u tes washed w ith tu rpen tin e . This process ; as , indeed ,

a ll direct prin ting processes , offers m any advan t ages for preparing colou r plates from a coloured object with o n e n egat ive . Th e

r egister of the separat e p lat e s i s very exact , w h ich is n o t alwayst h e case w ith a tran sf er process . I n reprodu cing lin e drawingst h e unn e cessary p arts on the ston e or plat e can be covered.

BRE AK ING UP THE H ALF-TONE ON TH E N E GA TI V E .

CHA PTE R V .

THE HALE -TON E PROCE SS FOR PHOTO-LITHOG RA PHY.

T HE half-ton e process i s u sed in photo l ithography t o reprodu ceo rigin al s w h ich do n o t con tain dist in c t l in es o r poin ts

,b ut closed

t on es,wh ich a1 e execu ted e ith er in o n e or several coloni s W i th

th i s process any col oured pic tu re, oil , water, past el , indian -in k or

s epia draw ing, as w ell as any ph otograph s from n at u re of l iv ingm ov in g scen es , or still l ife obj ect s c an be prepared for re p rodu ct ion o n t h e prin ting press .1 w ill first describe briefly the theory of the process, an d then

c om e to th e pract ical part .A s regards th e phot ographic part and the q u al ity o f th e n ega

t ive s , in th e present s tat e of t h i s m ethod of rep1 odu c t io n t h e

sam e prin ciples apply as in lin e reprodu ction,where they d iffer I

w ill m en tion th e sam e .

T h e durat ion of prin ting the tran sfer of the Im age t o t h e s t on e ,a s wel l as t h e o t h e i arrangem en ts w ill be de sc rib e d

C2I n t h e diffe ren t

p rocesses .W e divide this chapter again in to two section s1 . Methods I n which t h e h alf-ton e i s broken u p when makin g

t h e n egat ive .

2 . T he se m e thods in which the form ation of the grain is e ffe c t eda fter the n egat ive has been m ade by som e su itable m ean s .

1 . BR E A KING UP THE HA LE -TONE ON TH E N E GATIV E (A UTOTYPE).

Of th e variou s m ethods by which a breaking-u p of th e halft on es can be Obtain ed, the so called au t otypy is th e on e mostu sed practical ly . W ith this proce ss the half-t ones are broken u pin the n egative .

A s every im portan t techn ical discovery is form ed n o t a t on ce,

b u t m u st be m ade by a longer or short er series of sm aller disc ove rie s or im p I o vem en ts in order to attain th e hoped for goal so

was it al so w i th au totypy .

From the work of P au l Pre tsch , Mar1 io t , Brown

, an d Fred . E .

I ves the presen t state of th e cert ain an d beau t ifu l ly-workin g h alft on e process gradu ally evolved, and the last process , which o ughtt o be con sidered as the im m ediate predece ssor, is far o u tshone byau totypy as n ow practised .

E arly attem pts w ere m ade to obtain. a prin table Im age .on ston eb y breaking u p the c h rom at e d gelat in e .film

,so that an irregu lar

s e cal led serpen tin e grain was form ed on it, which corre spon de d

68 PHOTO-LI THOG RA PHY.

fairly w el l w ith th e th eory of li thography, b u t gave no preci sel in es and n o beau tifu l gradat ion s of s ton e . If t h e grain was

som ewh at t o o coarse th e effect of th e pic tu re was lost , th e t onegradat ion s w ere too far apart

, and on ly ligh t and Sh adows w eregiven ; if the grain was t o o fin e th e st on e was n o t prin table .

A fu rther experim en t was prin t ing a design over t h e origin al ,the strength of wh i ch h ad t o be brough t in correct proport ion t o th eo rigin al ; th e im pressin g of a design was al so t ried

,and wh en

u sing th is m ethod t h e c orrect angle of t h e in ciden t ligh t whenm aking the exposu re h ad to be taken in to accou n t .Fu rth er experim en t s , wh ich w ere prin cipal ly carried ou t by

Mario t , Cron enberg, an d oth ers, w ere fou nded prin cipally o n th e

basi s of breaking u p th e t on es in prin t ing. For th i s a l in eat u reo r screen o n glass , or a gelat in e film

,was in troduced between th e

n egat ive an d the sen sit i ve film . Oth ers , again ,coat ed th e blank

glass plat e w ith a lin eat u re , an d prepared th e plat e afterwardsw ith col lodion or gel at in e em u lsion for th e exposure .

It w il l be th u s seen h ow th is m eth od of reproduct ion developeds tep by step t ill n e t -work of silk m u sl in or woven h orseh air

, an d

fin ally grat ing im ages , stron gly redu ced by ph otography, w ereplaced in fron t of th e ph otographic plat e .

Th u s w ere effort s m ade t o m ake h alf-ton e pictu res su itable forprin tin g by lith o or typograph y, and alth ough th e e n d was veryn early at t ain ed , yet the c ru x was n o t qu it e solved . Th ese m eth odsdid n o t , h owever, yield t h e desired resu l t

,n am ely

,a beau t ifu l

sh arp c lear im age . Th ere was s t i ll req u ired a con siderable improvem en t of t h e exist ing m eth ods , and t h is was m ade byMeisenbach

,of Mu n ich .

Th e prin cipl e by wh ich Meisenbach prepared his im ages was

e ssen t ially di fferen t from th e previou sly-described resu l ts . H e

broke u p the half-ton es , al so by m ean s of a l in eature , in t o a prin table grain

, b u t th e process was essen t ial ly differen t from th e prev iou s m eth ods , in th at Meisenbach u sed a glass plat e on w h ich

,o n

a black ground,a gratin g was drawn t il l th e glass w as l aid bare

,

an d in th i s way prepared a lin eatu re wh ich con sist ed of clear glass.t ran sparen t l in es and absolu t ely opaqu e lin es .He produ ced

,first , an ordin ary n egat ive

,from th is a posit ive

,

an d from this,by th e in t erposit ion of th e l in eatu re

,t h e act ual

h alf-t on e n egative for m aking th e prin t in g plate . The lin eatu reor sc reen was in th e secon d exposu re in t erposed before t h e sen sit ive plat e, and h alf th e t im e of exposu re given ; t h en th e screenwas t u rn ed till th e l in e first obtain ed crossed t h e sec on d at an

angle of and then th e exposure was com plet ed . By th ism ean s an absolu tely certain breakin g u p of th e h alf-t on es in tom ath em at ically exact poin t s was attain ed , an d th e m ost im portan tstep m ade in m aking ph ot ography u sefu l for preparin g prin tingp lat es for th e two prin cipal m eth ods, typograph i c and l ith ograph ic .

Meisenbach h as called h is proces s “ au t o typy.

” It was,indeed

,

BR E AK ING UP TH E H A L F-TON E ON TH E N E G AT I V E . 69

som ewh at in con ven ien t , b u t h ad th e advan tage that o n the n egat ive and also o n t h e p o s1t ive an y retou chin g th at was n ecessarycould be don e .I can not h ere en ter in t o th e n um erou s sim plification s an d im

p rovem e n t s of Me ise nb ach’s process w h ich , as w ell I n t h e ph oto

graph ic process as al so in th e preparat ion of th e lin eat u re, w ere int h e cou rse of t im e m ade part ly by h im an d partly by CarlA n gerer

,Gillot

, Bu ssod an d V al adon ,Le fm an n

,an d ot h ers

,sin ce

,

o n t h e o n e h an d , it w ou ld carry u s t o o far, an d, o n th e oth er han d ,th ey m ay be con sidered as a n at u ral con sequ en ce of th e discovery.

I w ill on ly m en tion that it w as foun d aft er a short t im e that th etw o exposu res and th e produ ction of th e n ecessary posit i ve cou ldbe om it t ed

,an d that t h e l in eatu re cou ld be sim ply in terposed

before t h e sen sit ive plat e in th e firs t exposu re , by w h i ch an im

portan t sim plificati on of th e work was at tain ed,an d

,t h anks t o th e

con t inu ed perfect ing of th e processes,n o detract ion of t h e good

resu lt s was t h u s produ ced .

I do n o t con sider it su perfluou s to give a short expl an ation ofthe action of th e in terposed l in eatu re o n the photographic plat-edu ring exposu re .

If w e t ake,for the sake of sim plicity, n ot a pictu re, b u t a scal e

w ith fou r or five -ton e gradat ion s from l igh t t o deep b l ack, th elight ton es w ill act m ore or less o n t h e sen si t ive ph otograph icplat e accordin g to their degree of brigh tn ess , b u t as the rays oflight have t o pass throu gh th e cross - lin ed screen in t erposed b etween th e l en s an d sen sit ive plat e

,an d as the rays c an on ly pass

t h rough th e t ran sparen t parts an d n o t through the opaqu e , n o

hom ogen eou s su rface i s obt ain ed on t h e n egat ive,b u t a t on e pro

duc e d by t h e cross-lin es of the screen . If th e ton e was verybrigh t

,th e rays reflected w ith great in t en sity on the sen sitive w i ll

com pletely decom pose the silver film . S in ce th ey are preven t ed byt h e screen from actin g w ith equ al power o n all places of the surface

,these places w il l show very plain ly o n th e n egat ive

,an d t h e

resu lt is therefore a darker ton e on t h e sam e , wh ich i s m arkedw ith bright fin e l in es

,corresponding in thickn ess t o t h e screen

l at e .pIf th e origin al ton e was darker so m an y rays of light w i ll n o t be

reflect ed,and these have thu s n o t th e power to im press t h e s c reen

o n t h e sen sit ive plate in fu l l in ten sity ; th e resu l t i s therefore o nth e n egat i ve a t on e wh ich does n o t con tain su ch strong dark lin esas the first ; t h e t on e appears lighter in th e n egative

,an d in t h e

prin t from the sam e darker t han th e first .

I n th e reprodu ction of deep black surfaces fin ally n o rays of,

light are reflected,therefore n o rays of l igh t c an pen e trat e th rou gh

the screen,and becau se actu ally h ere n o .chem ical ch an ge of th e

l ight sen sitive film t akes place, w e obtain a n egat ive w h ich is

c lear an d tran sparen t in these places, that is t o say w ithou t anyin terruption

, which gives in th e prin t a fu l l black t on e.

70 PHOTO

I n this p rOc e ss there com es , h owever, t o ouraid a very im portan tphysical law,

nam ely, t h e diffrac ti on of l igh t . A ray of lightp assin g t h rough a rou n d h ol e or a slit an d falling o n t o a blacksu rfac e

‘

i sl

rep re se n t ed n o t th e sam e size as th e sl i t,b u t m ore or

Iess broaden ed t h e‘

m ore t h e re c e ivm g su rface is m oved away, andin

’

the m iddl e‘

th e brigh test l igh t w il l be, an d thi s gradu ally fadesoff in to shadow towards th e m argin .

If we take ‘

n ow t h e Opposi te, and u se in stead of t h e hole or sh ta

‘ black surface 011 a conglom erat e of su ch in the form of poin t s

,

squ ares , or oth er geom etrical figu res , an d if t h ese be placed beforea

' screen illum in ated w i th a brigh t l igh t,t h ese figu res becom e

somewh at sm all er w ith t h i s brigh t illum in at ion, wh il st w ith a

weaker il lum in at ion t h ey are represen t ed in correct strength .

W h ere th e light ac ts in its fu l l in ten sity,or in excess

,in a

m an‘

n e r‘

of speaking it i s diffracted or ben t over t h e figures, an d

p roport ion at ely m akes th em sm aller.

Th is law does good s ervice in au totypic work .

A s We h ave seen ,t h e ray s of light m u st pass th rou gh th e screen

du ring e xposu re . Th i s screen con sist s of equally th ick opaqu eblack an d t ran sparen t white lin es . Wh ere th e ligh t acts w i th fu llin t en sity it w ill be m ore diffract ed over th e black lin es . I t m akesth e l in es of th e screen broader o n th e n egat ive

,and w ill , therefore,

h ave‘

m ore covered places , wh ich in t h e after prin t ing of t h e prin t scan n ot be pen etrated by the ligh t , and th u s represen t th e l igh t ,plac es in th e prin t covered w ith fin e dots .

Th e darker t h e t on e t h e l es s th e rays of light reflected, an d th eless

,th erefore , c an th e ligh t be diffracted . A s th e t on es ge t darker

th e l in es of t h e screen bec om e of eq u al valu e on th e n ega tive , t il lfin ally

,wh en at t h e opposi t e e nd of the screen , t h ey tot ally

d isappear in t h e deep blacks .A valuabl e qu al i ty of a correctly-prepared au totype is , therefore ,

th at th e “ covered lin es or th e covered grain appear of differen tstrengths o n th e n egat i ve . I n the high l ight s th ey are stron ger

,in

the h alf-ton es w eaker, t ill finally in th e black parts th ey h avet otally disappeared .

A fu rth er n o t less valu abl e property is that th e grain in t h ehigh est ligh ts is n o t sharply defin ed, does n o t appear as a squ are

p oin t, b u t i s rou nded by t h e diffrac tion of light , which gives aso fter, m ore beau tifu l appearan ce an d plast icity .

Whil st th e‘ light reflected from th e brigh test parts of th e draw

ing' acts w ith fu l l in ten sity, and is di ffracted over the figu res

st an ding in its path an d m akes th e sam e sm aller, and cu ts off th esh arp corn ers an d gives m ore covered su rfaces to the n egative, asit dec reases according t o th e m ore or less deep shadows of th edraw in g, and c an

’ on ly ac t n ow w ith less in t en sity th rough theo pen pl aces of the screen ,

th e resu lt i s that t h e poin ts becom el arger, till fin ally in t h e deepest parts it i s qu i t e in active , and th eshadows begin to block .

‘

Th e act ion of t h e l ight rays of differen t

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72 rHo 'ro-e n o em rnr .

and sharply drawn in m any ton es , the light reflects the leastalterat ion of ton e in the size of the grain .

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F ig. 8.

A s prev iou sly m en tion ed, th e sm all est poin ts represen t th e

high est l igh t s of th e drawin g t h e l arger,according to o u r graphic

represen tat ion ,t h e darker ton es , b u t a correct reprodu ction of th e

ra i n .gI n a sim il ar way obviou sly the form ation of th e l in es on the

n egative beh ave with an in terposed bu t n o t revol ved screen . Hereal so th e lin es in th e high lights of the n egative appearm ore coveredthan in t h e sh adows .Th e proportion of grain c an

,if the origin al requ ires it

,be so far

altered by n o t givin g equ al exposu res for each posit ion of th escreen— for in stan ce

,in t h e proportion of two t o o n e or th ree to

o n e . W e ob tain t hen o n th e given sch em e l ess closed ton e gradat ion s

,3,4,and 5 , and ju st before 3, an d between an d after 5 , ton e

gradation s, n o single black and white poin ts , b u t m ore or less j aggedblack or wh ite lin es , wh ilst t h e open black grain in 1 and 2 becom esm ore an oval in stead of th e rou nd form in 6

,and beyon d th e rou n d

Open ings are drawn ou t in to oval s .W e h ave, h owever, in au t otypy still the physical law,

wh i ch i svery u sefu l to u s, an d that i s the greater or less distan ce of th ep oin t from t h e l igh t su rface. The n earer a poin t or a figure isbrough t to the wall on which it sh ou ld throw the shadow ,

th e

great er the size of th e origin al , and so m u ch sharper w i ll be theou tlin es of th e shadows . Th e m ore the poin t or th e figure i s

; 0 0 0 0 0

BRE A KI NG UP TH E HA LF-TON E ON TH E NE GA T I V E . 73

rem oved from th e wal l th e l ess th e shadow w il l correspond to th esh ape Of th e Origin al ; it w il l be sm aller an d les s defin ed . Th e

shape w i ll al so frequ en t ly ch ange , an d a sq uare w il l becom e a

round . W e have th en in t h e n ear or di s tan t posit ion Of th e

l in eatu re t o t h e sen sit i ve p la te , o n w h ich it throws i ts shadow , an

im portan t assi s tan ce t o ac t on t h e gen eral ton e grada t ion s Of th e

im age . Le t u s rem em ber that in focu ssing t h e shadow-form ingObj ect on t o th e su rface o n wh ich th e l igh t fa ll s

,w e Obtain t h e

sam e form ed in all its actu al i ty o n t h e receiving su rface t h erefore,

when thi s refers t o a lin eat ure w i th equal p re port ion s Of black an d

white , we Ob tain th ese in equal rat io . Wh e n,h owe ve r , we rem ove

t h e l in eatu re from th e l ight-receiving surfac e, t h e sh adows whichi t throws c on tract , the ligh t s predom in ate , we Obtain n o l onger t h era t io Of 1 1 between ligh t and sh adow, b u t abou t l and

so on .

By placing th e l in eatu re close to t h e sen sitive plat e , we Obtainm ore closed ton es , an d as th i s gradat ion of t on e i s carriedn atu rally throughou t th e wh ole of t h e im age , also l es s h ighligh t s , l ess deep , m iddl e shadows , wh il st t h e deep sh adow sappear in their n atu ral stren gth . W ith t h e rem oval Of t h e

l in eat ure from t h e sen sitive plate , o n th e oth er han d , t h e rat io Of

t on es for th e whole im age, as w ell as for th e det ai ls , i s displaced .

I n t h e first place we sh all Obtain a pictu re which con t ain s m orecon trasts of black and wh ite . The ligh t ton es becom e c on siderablyl igh t er by th e redu ct ion Of the sh adows . The dark par ts , o n t h eo th er h and, attain fu l l vigou r. I n t h e first place

,t h erefore

,t h e

o riginal h as t o be con sidered as regards t h e distan ce Of t h e

l in eatu re from the sen si t ive plate . Obviou sly, th erefore, n o

accu rate direction s can be given in a case where feelin g an d

e xperien ce are requ ired. N ext to the origin al,the n u m ber Of t h e

l in es on t h e screen has to be con sidered . A s a ru l e, o n e u sesl in e atu re s w it h five or s ix tran sparen t and opaqu e l in es t o t h e

m i ll im e tre ( 2 125 -150 to the in ch), an d for t h ese a distan ce ofto 1 m m . l

lg-n th in ch) from th e sen sit ive plate i s gen er

ally su ffic ie n t for m ost cases . W ith a less n um ber Of l in es th ed istan ce c an be in creased .

A u totypy is a process in which unprin tabl e half-ton es c an bebroken u p by t h e u se Of a w ell-defin ed physical law in t o a

m athem at ically determ in ed grain , an d th e size Of th e grain can

al so be regu lat ed t o a certain exten t w ith certain precau t ion s .

I t i s,therefore

,easi ly u n derstood that the au t otypic process i s

n ow very gen eral an d m ost u sed, an d n o t on ly in the lim itedd epartm en t Of ph oto- lith ography, b u t in a m ore extended way ,

does excel len t service for t h e preparation Of i llu stration s of allkinds

,for the s im ples t pictu re for the daily paper as for t h e

fin e ly-prin ted m agazin es an d j ou rn als

,for sim ple m on och rom atic

p rin t ing, an d for t h e highest colour prin t in g.

W ith accu rate kn owledge an d comm an d Of th e techn iqu e of

74 PHOTO-L ITHOG RA PHY.

photography and li th ography , th ere i s requ ired before everything,for s uccessfu l work

,a fau l t less screen plate . Th e indispen sable .

requ irem en t s wh ich m u st be fou nd in th e screen are absol u telyopaqu e b lack lin es and bare gl ass in t h e whi te lin es . The hom e

preparat ion Of s uch a s creen pla te is a som ewh at di ffic ul t m atter,

an d will n o t be ab solu t ely s uccessfu l if o n e h as n o t a faul tl essru l ing m achine, a com posi t ion w h ich i s thorough ly Opaq ue , wh ichadh eres well t o t h e g lass and gi ves clean

,sharp lin es in rul i ng,

an d wh ic h does n o t ch ip,and it w ill req u ire a trem endous ex pe n- x

d it u re Of pat ience an d perseveran ce . Glass sc reen s of excell en tqu ality m ay n ow be Ob tai ned comm ercially .

For reproduc t ion Of t h e very h ighe st quality,a drawn and

e tched screen plate is m ore s u i table t h an o ne . m erely rul ed on

pigm en t, wh ich n ever gives s uch sharp resul ts .From variou s firm s e tch ed screen plat es m ay n ow be obtai n ed.

e ith er as s ingle or crossed-l in e scree ns, which fu lfil all require

m en ts .

T h e bes t screen to,

u se i s on e w ith five or six Opaqu e an d‘

tran sparen t l in es t o t h e m il lim e t re, wh ich corresponds w i th

to poin t s t o t h e sq uare cen t im etre . T h e aboven um ber Of lin es wil l s u ffi ce for n early all w ork

,an d su ch screen s

give reproduct ion s in wh ich th e grain is n o longer visible to th en aked eye

,bu t appears as a closed t on e . I t i s n o t advisab le t o go

beyond t h i s n um ber Of l in es,except in Spec ial c ases

,wh en th e

det ail s of th e draw ing in t h e origin al are special ly sm al l. W i th:a sm aller n um ber Of abou t t h ree or four lines t o t h e m illim etre

,

too c oarse a grain res ul t s,Of wh ich t h e individual poin t s becom e

t o o plain ly visible,and t h ese are di s trac ting an d ac t rough ly , a nd

do n o t accurat ely reprodu ce th e gradation Of t on e .

Th e best proport ion be tween Opaci ty and t ran sparen cy is 1 1 .

From this i s Ob tain ed, according to m y Opin ion ,th e m ost b eau t ifu l

and restfu l ton es . It m u s t also be rem em bered that th e Opaqu e;spo ts ac t u ally lose con siderably in strength in t h e brigh t er

p orti on s of th e pictu re by th e spreading ac t ion Of th e l ight .T h e prin t ing m ay be don e on bich rom at ed gelat ine paper

,

w ith wh ich ,however

,extrem ely accurat e ink ing u p of th e prin t

i s essen t ial,an d t h e prin t s m u st n o t h ave tOO m u ch ink an d m u st

be very carefu lly prin t ed. If,however, very good ,

clear n egat ivesare u sed

,either of th e direct prin t ing m eth ods , as already

described in Ch apt er I V .,is t o be preferred. (Se e N o . 4: S upple "

m en t .)

2 . PROCE SSE S I N WH IcH TH E GRA IN I S NOT

FORME D D URING THE E X POSURE .

Of the m any existing processe s by wh ich th e breaking-u p of th ehalf-ton es in to prin tab l e l in es or grain i s effected, n o t in th e

n egat i ve, b u t subsequ en tly by m e ch an ical an d ch em ical action on‘

t h e s ton e or plat e or th e . t ran sfer. film,I will on ly m en tion those

THE c o'

LOUR PRINTI NG'

PROCE SS. 75

wh i ch appear to m e to be th e m ost im portan t, the n e w m ethodswh ic h have already fou nd firm footin g 1n pract ical w ork or wh ichappear likely to do SO

'

. A ll t h e e lde r processes, which w ere eith ern ever ac tually su ccessfu l or h av e been su perseded o n accou n t Ofdifficu lty Of working, We m ay properly pass over.

(A .) THE PATE NT A SPHALT PROCE SS OF ORE LL, FUSSLI , AND 00.

USE D FOR THE PRE PA RATION OE COLOUR PRI NTS.

I h ave already m en tion ed that the u se Of light sen sitiveasph alt for th e preparation Of prin ting plates for t h e variou sbran ch es i s by n o m ean s n ew .

Th e fun dam en tal prin c ip l es Of th e well -kn own processes we find

also u sed in th e p i e c e ss Of Orell , F iissli, an d CO .

Th e grain ed s ton e is coated w ith a thin film Of light -sen sitiveasph al t , t h e com posi tion Of which we hav e previou sly learn t

, an d

exposed u nder a reversed 01 stripped n egative . Th e 1m age aft ercorrect exposu re i s developed, an d th en ,

according tO the con stru et ion Of th e as phal t, in com bin at ion w ith th e grain in g Of th e ston ean d th e developer

,there i s form ed a fin er or coarser grain

, or a

closed or open im age .

T h e developm en t is effected with petroleum ,to which On e -fifth

or on e -sixth of its volum e Of ben zin e i s added, or w ith tu rpen t in ealon e . D evelopm en t takes pl ace rather rap idly

,an d after a sh ort

tim e th e im age appears on t h e ston e . The prin t i s then treated as

was suggest ed in asph al t prin tin g ; t h e ston e i s first gum m ed,an d

th en by rollin g u p w ith ink an d et ching ren dered su itable forprin tin g . The pictu res produ ced by th i s have a very fin e grainand are in appearan ce v ery m u ch l ike good c ollotypes ; stil l two01 m ore t on es are n ecessary t O Obtain an absolu t ely closed and

v igorou s act ion .

V ery sim ilar to Orel an d Fussli’s process i s the fo llow in g, al sopat en t ed .

(B.) TH E COLOUR PRINTING PROCE SS OE W E ZE L AND NAUMANN OE

R E UD NITZ , LE IPZI G .

I n this process al so al l t h e colou r ston es of a ch rom e pictu re areprodu ced from a sin gl e stripped and reversed n egative wh ich it aken Of t h e origin al . For t h e p 1 e p arat ion of any colou r ston et h ere a1 e th i ec distin ct stages . The first stage is the exposu re,t h e secon d th e developm en t , an d th e third th e developm en t cont in ned st ill fu rther, an d any n ecessary sm all help by the lithograph er . I n each Stage a Special m ode Of t reatm en t i s requ ired,accordin g t o whether th e ston e in qu estion i s to be u sed for a light ,a m ore v igorou s , or fu l l colou r. The ston es for grey an d th e lightbl u e o r l igh t re d inks— thu s those for m any su rfaces, b u t w ith fewd e tail s— are t reated differen tly to those for yellow,

the secon d red

7 6 P HOTO-L I THOG RA PHY .

or bl ue ; and th ese, again ,differently to those for brown or q u ite

dark c olou rs .E veryon e only sligh t ly con versan t with colour prin ting kn ows

that t h e first plates are u sed for t h e gen eral t on es of th e pictu re,

a nd con tain ,t h erefore, fe w de tails , and with th e exception Of t h e

high es t ligh t s are t olerab ly fu ll ; t h e latter plat es , o n th e otherhan d, wh ich are devoted t o t h e darker colou rs

,con tain l ess t on ed

su rfac es , b u t , o n t h e con trary, m ore detail s Of t h e drawings .I n order t o at tain t h i s correctly t h e th ree stages Of th e produ ct ion of t h e plat es are carried o u t w i th th i s e nd in V iew .

I t S hou ld s t i ll be m en t ion ed that th e m ore or less fin e grain ing Ofthe ston e de term in es t h e gen eral rat io Of th e grai n Of t h e pic t ure .

T h e first s tage is th e exposure of grained Stone coated w ith

ph alt . Wi t h longer or sh orter exposure it is possible t o m aket h e asph al t fi lm m ore o r less sol uble , t h at i s t o say, t o m ake thesam e m ore or less capabl e Of resist ing eth ereal Oil s .I t i s t h erefore possib le at t h is s tage , by long exposu re Of th e

ph al t film , t o give to t h e co lour s ton e for brigh t e olo urs m ore

t on e and les s de tails . T h e s ton es for th e darker inks are print edfo r a Sh ort er t im e, and t h e asph al t film i s less c apable Of. w ithstan ding t h e solven ts , and t h e res u l ting plate con tain s l ess tonesan d m ore details. Fin ally, t h e plates for t h e deep colours are

n orm ally prin t ed ; th e asph al t film i s still less resis tan t,an d c o n

sequ en t ly t h e ston e wi l l on ly have ton e and details o n th ose placesw h ich in prin t ing ough t t o be t h e darkest .I t i s possible , therefore , by correct m an ipu lation Of this Opera

t ion,t o Ob tain approxim ately t h e correct colou r plate .

There is,h owever, in t h e second process a corrector for th e first .

The developm en t m ay be SO perform ed that by t h e longer orSh ort er u se Of s trong sol ven t s , Hungarian or Ru ssian t u rpen tin e

,

m ore or less Of t h e asph alt w ill be dissolved . Th u s if a slighte rror i s m ade in prin t ing it c an be m ade good in developin g. A s

a ru l e,th e s ton es for brigh t colou rs , which con sis t of m any t on es ,

are n o t developed so long as those for the stronger colou rs . Th e

actu al ston es for t h e deep colours are very strongly developed, SOt h at alm ost all t h e del icat e parts Of th e pictu re disappear, andOn ly th e den se strong part s rem ain o n the st on e .

S t ill th e fin e det ail s wh ich are to be fou nd in the vigorou spart s

,and which can n ot be recogn ized , m u st be brought ou t . Th e

fin e part s Of t h e draw ing m u st be q u ite clear if the details are t obe recogn ized , or t h e picture w i ll be a fu zzy copy Of th e origin al

,

w an t in g in s tru ctu re .

Th is fau lt is rem edied in the third stage of the treatm en t,in

which a strong developm en t Of the picture is effected with stronga ct ing Oil s or ben zole and turpen tin e . A s this operation ,

h ow

ever, wou ld also wash away such delicate places which ought t o

rem ain o n th e colou r s ton e, t hey m u st be covered with solu t ion of

gum and all owed to dry . Then th e se parts n o t covered with gum ,

J . B A RTOS’P ROCE SS . 7 7

in which th e details Of th e im age can n ot be seen , are pain ted for a .

longer or short er tim e , as m ay be requ ired, w ith a bru sh dipped int h e developing sol u t ion ,

and when correct ly developed m ay b e

covered u p . Th e l igh t er places are t reated for a Shorter tim e, th every dark p laces for a longer t im e .By th i s treatm ent t h e par ti cu lar parts Of th e pic tu re becom e

ligh t er and ligh ter, th e det ail s appear m ore an d m ore ; and,

fin ally , t h e wh ole pictu re sh ows as it Should do . Th en t h e gum i s .washed OE and t h e st on e s ubj ected to th e already described treat sm en t , so as t o m ake it su itable for prin ting in qu an t ities . Fin ally,t h e li thographer c an m ake correct ion s w ith a n eedle or tu sch .

Th i s process m ay be u sed ,t h erefore

,t o prepare c olour-prin ting

plates from a n egat ive Obtain ed in t h e cam era from an Oil pain ting or any colou red origin al .T h e n egati ve for th i s process m u st contain all th e detail s very

clear , m u st be soft , an d n o t be t OO den se .

Th e differen t colou r plat es are th u s in this process Obtain ed bylong or sh ort prin ting, by strong or w eak developing, an d fin allyt h e detail s in th e dark plates are Obtain ed by separat e developm en t an d covering u p th e o th er places w ith gum .

Th e break ing u p Of th e h alf-ton es in to prin ta ble grain'

is effectedby grain i ng the st on e , before coat ing w i th th e ligh t sen si t iveasph alt fi lm . On th e fin er or coarser grain in g Of t h e ston e depen dsalso t h e s truc tu re Of the grain Of the im age .

This process y i elds th e m ost beau t ifu l res u l ts w ith correct .

m an ip u lat ion , an d in the han ds Of an expert ph otographer an d

li thographer is a valu abl e aid to the preparation Of colou r plates .

The process is pat en ted .

(C.) J. BARTOS’ PROCE SS FOR PRE PA RING PHOTO-LITHOGRA PHS A ND

PHOTOTYPE S IN GRA IN AND HA LF-TON E .

Bartos’ process belon gs to those in which th e breaking up of th ehalf-t on es in t o a prin table grain i s effected subsequen t ly o n t h e

plat e or ston e by m echanical m ean s . Th is i s attain ed in a veryorigin al m ann er by m ean s Of a san dblast, wh ich m akes th e half-uton e prin table . We have here n o t the breaking u p of th e a h alfs

t on es in a m athem at ically regu l ar m ann er, dependen t o n op t ical

l aws , as i s t h e case w ith au totypy, b u t a m eth od sim ilar t o that Of"

Pre t sch,wh ich Obtain s the prin tabl e grain by reticu lat ion of t h e

c h rom at ed gelat in e film, or other di scoverers wh o at t ain th e sam e .

resu lt by asph alt du stin g or som e other m ean s .For t h i s process a wel l-polished litho ston e or zin c plate is coated

w ith a th in film of varn i sh , com posed Of

ChloroformMast i cA sphaltBe n ze le

Lin seed Oil

7 8 PHOTO-LI THOGRA PHY.

O n the ston e or plate thu s prepared 18 tran sferred a carbon 1m agein half-ton e .

Th i s pigm en t film, when c om pletely dry

,i s

,gflowe d o ver w ith a

m ixtu re Of

Glycerin eWaterA lum

and this sh ou ld be all owed tO ac t for about five m in u tes an d th enrem oved wi th blo tt ing-paper. A f ter thi s Operat ion t h e pigm en tim age c an be easily destroyed . T h e pigm en t im age i s n ow exposed t 0 t h e ac tion Of a weak san dblast . Th e san d act s o n ther eli ef im age and gradually destroys it

,an d SO th at th e film Of var

n ish u n dern ea th is gradually grai ned .

A fter th e pigm en t film has been rem oved the pictu re Shows ina ll it s de tail s in grain o n t h e varn i sh Of th e s ton e or plate . Theim age is n ow v isi bl e o n t h e film Of varn ish

,ac c ordi ng t o th e

s t rength Of th e t on es in part i al grain ing,and c an b e e tch ed in to

t h e ston e or plate .

Th i s i s effec ted by e tching w i th phosphoric acidW at er 100 g.

Phosph oric

W h en th e e tch ing solu tion h as acted for abou t two m in utes,th e

.s ton e is w ash ed an d coated with a sol ution Of gum

W ater 100 g.

G um arabic 5

a n d all owed t o dry .

Then the film Of varn i sh is rem oved w ith a p ad Of cotton w oold am ped w ith tu rpen tin e , the dry ston e rolled u p w ith lith o ink ,

d am ped, and the excess Of ink roll ed Off. Th e picture n ow Sh owsw ith all it s fin est detail s o n the ston e

,an d c an be prin ted .

I n preparing a relief prin tin g plate the film Of varn ish form s ther esi st for th e first etching . It ’i s then rol led u p and e tched in th eu su al way .

For preparing larger pictu res on ston e or m etal plates , in whicht h e grain m u st be coarser than w i th sm all p ic tu I e S , th e fu llydeveloped and still dam p pigm en t im age is du sted with powderedresin and th e film allowed t o dry w i th

o

the powde r adh ering to it .T h e pigm en t Im age th u s du sted 1s treated, as previou sly de sc I ib e d,w ith alum an d glycerin e

,exposed to the action of t h e sandblast

,

a nd then etched with ph osphoric or n itric acid .

A s the soft pigm en t film receives a grain by the du s ting,this is

r eprodu ced Of th e sam e size by the action Of th e sandb last on thefilm Of varn ish o n th e ston e or plat e .

The prin cipal poin ts of this process of. preparing photo litho

g raphs Or pho totypes 1n half ton e, w ith a grai n are as foll ows1 . From th e ph otographic n egative a pigment imag e is taken

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80 PHOTO-L I THOGRAPHY.

d istribu ted by m ean s Of a l ithographic ink rol ler, which m u st n o t

be u sed for any other pu rpose b u t th is , t i l l the coating is absolu telyeven and sh ows a l ight brown colou r.When this film h as becom e quite hard

,fin e parall el lin es are

drawn o ver th e whole su rface Of ' the ston e w ith a very accu rat ew orking ru l ing m ach in e, by m ean s of which from five t o t en lin esper m i ll im et re c an be ru led .

W h en t h e ru l ing is fin i shed the ston e i s given a m argin Of wax,and qu ickly and even ly flooded w ith the follow ing e tch ing flu id

P ure n itric acid 0 16 parts .A lcoh ol 36 per cent . 060Wat er 35

A nd, watc h in hand , i s e tch ed for about half-a-m in ute .

In s tead Of t h e above a solu t ion Of

Glacial ace tic acid 2 g.

100

m ay be u sed and allowed t o act for h alf-a-m inu te . Th e ston e ist h en w ell w ash ed u n der a strong stream Of wat er

,al lowed to dry ,

and covered with l in seed Oil . A fter abou t five m in u t es the wholeOf th e ston e m ay be washed w ith turpen tin e . Th en it shou ld beinked u p w ith a p ad, care being taken th at all lin es take th e inkw ell an d even ly . This patt ern ston e serves as the origin al platefor t h e subsequ en t ru led tran sfer.From th e origin al ru led ston e can be m ade

,according to the

n atu re Of th e original , a single, double, t riple, or fou r-fold t ran sfer .

For preparing a st on e w it h a ru l ed t ran sfer,a sm oot h ly groun d

ston e wel l poli shed w ith oxalic acid i s even ly coated w ith sen sitiveasph al t solu tion . 011 t h i s , when dry , th e desired single or crossedt ran sfer from th e origin al ston e i s m ade, and du sted w ith bron zepowder. Th i s adh eres to th e l in es Of th e patt ern

,an d in com bi

n ation w ith t h e prin t ing ink prot ects th e asph alt h lm u ndern eathfrom th e act ion Of l igh t . D u rin g the subsequ en t exposu re , wh ich ,

according t o th e sen sit iven ess of t h e asph alt and in t en sity Of th e

l igh t,c an last from a half t o two h ou rs or m ore , the particles Of

asph al t n o t covered by th e bron ze powder becom e in solu b l e, wh ilst

t h e prot ected part s preserve th eir solubil ity .

A fter correct exposu re th e surface Of th e ston e i s carefu llywash ed w ith a tu ft Of cotton wool soaked in Oil Of turpen tin e

,

when th e p ar t icles Of asphal t u n derlying the bron zed lin es dissol ve . Th e ston e at these parts i s laid qu ite bare , and thereforem ade c apable Of bein g su bsequ en tly etched . The deep etching of

the pat tern is effected in the sam e way as was suggested in th e

preparat ion Of the m other pattern ston e .

By this m ethod a positive pattern is Ob tam ed, that 1 s to say, th elin es prin t

,an d t h e im pression show s therefore a black n etwork .

A second m ethod Of m aking a pattern tran sfer con sists inm akin g a pu l l from the origin al ston e o n to chalk tran sfer paper.

LI'

l‘

HO-H E LI OG RA V URE ; 8 1

T hi s pu ll i s then dam ped o n the back, and when ju st properlydam p is laid on

"th e poli sh ed stone (w i th ou t any asphalt) and th e

t ran sfer m ade . I n order t o rem ove t h e chalk paper w ith ou tdam aging th e pat t ern t h e ston e i s covered w ith warm water, whent h e lin es w ill di ssolve . Th e sim ple pattern w ill n ow be fou n d o n

t h e ston e, wh ich sh ou ld n ow be w ell wash ed, th en du sted w ithresin powder

,which shou ld be m e lte

’

d o n w ith ether vapou r.

T h en if t h e direct ion of t h e first l in es was vert ical,the secon d

t ran sfer i s arran ged with th e direct ion of th e lin es h orizon t al tot h e first

, an d th ere i s thu s ob tain ed a sim ple crossed pat t ern .

With fou r-fold crossed pat tern s th e subsequ en t pu l l s are m ade inOpposite diagon al direct ion s . A ft er each t ran sfer th e ston e is w el lw ashed, allowed t o dry , th en du st ed w ith resin powder, an d w ithe th er m elt ed o n t o th e pa t t ern .

T h e s ton e i s n ow deep e t ched w ith dilu te n itric or ac e t ic acida nd covered w ith lin seed oil .By th is m eth od a grain in stead of l in es is obtain ed. By

p oli shing the ston e and t ran sferin g on t o it, as well as by et chingt h e places n o t covered by th e ink , w e have the pattern reversed

,

that i s to say,it i s con verted in to grain .

For fu rther operat ion s of li th o-h eliogravure a very clear an ds oft n egat ive is requ ired, from wh ich a glass t ran sparen cy i st aken . Un der th i s t ran sparen cy pigm en t paper sen sit ized on a20 p er c en t . solution of potassium bich rom at e i s prin t ed to 8 or 10d egrees V ogel . P rin t ing m u st be very c arefu lly perform ed

, as

w ith u nder-prin ting t o o m any detail s are lost . T h e expos edpigm en ted paper i s wash ed in cold wat er, laid film side down o n

t h e previou sly prepared ston e, an d pressed in to con tact w ith an

india-rubber squ e egee . I t shou ld then be allowed to dry in a n o tt oo dry or too warm place.T h e ston e sh ou ld n ow b e placed in a trough w ith warm water

o f abou t 40 to 45° C ., and c are shou ld be taken to obtain wat er ofa s even a t em peratu re as possible . A fte r abou t five m in u te s th ep aper w il l be free from th e ston e, which shou ld rem ain in theb ath and be developed so long by shaking in order that the wat erm ay flow even ly over it till th e im age appears qu ite distin ct a

n egat ive im age i s thu s obtain ed o n the ston e. The film i s thena l lowed to dry spon tan eou sly for four or five hou rs til l th e p igm en t im ag e has becom e q u ite hard .

For etch ing a solu t ion of perchloride of iron of variou s strengthsis u sed, 40, 37, 33, an d 30

°Beaum e. W i th subj ec t s very ri ch in

t on es all fou r w ill be u sed w ith sim pler su bj ects on e or th e o th eray be om i t t ed .

T h e et ching w ill begin , as a ru le,w ith th e 40

° solu tion . Th ef erric chloride w il l first dissolve the t h in

,harden ed pigm en t film

and then go through th e open lin es of the pattern,where it w ill

.attack th e ston e an d etch t h e deepest parts ..S lowly the ferric chloride dissolves also th e thicker pigm en t

G

8 2 PHOTO-L lTHOG R-A P I I Y .

fi lm — begin s al so to e tch the ston e th ere , b u t less deeply. To t ellwh en th e fou r sol u t ion s sh ou ld be u sed in turn ,

as wel l as t h ecorrect mom en t t o in t errupt th e etch ing r

,eq u ires con siderable

experien ce . The 30° solu tion ,th e w eakest of t h e ferric ch l oride

solu t i on s,i s u sed last

,and 1 11 con seq u en ce of th e g1 eater propor

t ion of water possesses a sol ven t power for th e wh ole of th e ligh th arden ed pigm en t film .

-A ccurate direc tion s as t o h ow long t h ee tc h ing w i th t h e differen t solu tion s i s to be con t in u ed can n ot b egiven

,as t h i s depends u pon th e character of t h e subj ect as w el l as

u pon t h e thickn ess of t h e p lgm e n t im age . I t m ay be alwaysa ssum ed, h owever, th at any indi vidual etc h ing ough t t o last u n dern o circ um s tan ces longer th an th ree t o four m inu t es . W ith wellc overed s ton es the first etching sh ou ld n o t be allowed to ac t so longas t h e l ast , and m

'

ce c erso‘

t w it h less covered ston es .A s soon as th e 1m age shows th e correct character through th e

e t ch ing solu t ion th e s t on e sh ou ld be brough t u nder t h e tap m th e

t rough and q u ickly wash ed with clean cold water. The su rface oft h e im age sh ou ld th en be flowed over w i th oil of tu rpen tin eo rder to rem ove t h e asph alt and gelat in e film

,an d fin ally well

w ash ed w i th th e rose and allowed to dry . Th e pict u re w ill b efou nd deeply et ched in to th e sto n e . Th e s ton e i s n ow sm earedo ver w i th l in seed oil , inked u p , and further t reat ed as in ordinaryl ithogravu re .

I n this process the n egative pigm en t 1m age i s tran sferred to th es ton e and t h e prin t ing im age prepared by e tch ing ; the form ationo f th e grain i s produ ced by th e pattern prin t ed either on a

p olish ed ston e , wh en it i s con verted in t o poin ts , or t h e tran sfer m aybe effected o n t o an asphalt ed polished stone

, when a n etwork of

l in es w i l l be obtain e d .

For dark subj ects the latter process is better, for l ighter sub

j e c t s th e gi ai n .

Pr in t ing frr om su ch a plate has m ore sim i l arities with etching

p rin ting th an f1 om ston e ; the efi e c t of the ink i s v ery good and

e xpress i ve .

V a1 10 118 pic tu res execu ted by E ckst em an d m o ur establ i sh m en tin o n e or m ore colours have proved th e valu e of this process inprac t i ce .

T h e foregoin g are th e diffe i e n t ph oto lithographic m eth ods forobtain ing prin t ing im ages in h alf t on e

,an d alth ough 111 n o way

exh au st ive, yet it appears to m e that they are practically th e m ostim portan t.

N E G AT I V E TRA NSFE R W I TH B I CHROMA T E D G E LA T I N E PA PE R. 83

APPEND IX .

1 . NE GATIV E TRANSF E R WITH B ICHROMAT E D G E LAT lNE PA PE R.

THE properties of bichrom ated gelatin e paper can also be very w ellu sed for t h e so -called n egative prin t ing

,an d this m e thod offers

m any advan tages .I n order t o conv ert a positi ve prin ting 1m age in t o a n egative

variou s m eth ods m ay be u sed th e m ost con ven ien t for t h e lithograph er i s t h e fo llowing z- A good lith o ston e is first groun d inth e ordin ary way an d t h en the su rface ru bbed w i th a p ad and

oxal ic ac id solu t ion t i ll it has a h igh glaze or pol ish . On t o thi sston e is then t ran sferred a sharp im pression in a n o n -greasy inkfrom t h e positive prin ting im age . A ccord in g to t h e des t in at ion ofth e st on e for large or sm all editi on s o n e of two processes m ay beadop ted . I f a t h ou san d or m ore pu ll s are requ ired from the st on ethe t ran sfer m ay be du sted w ith resin powder , an d this m elt edw i th th e bu rn ing, heating, or eth er process an d th e draw in g et chedin reli ef wi th 8 t o 12° n i tric acid an d gum . Th en th e s ton e m aybe w el l wash ed w ith water an d the acid rem oved w ith on e to twoper cen t . ac et ic acid .

For sm all ru n s th e first etching i s om itted , and the ston e treatedwith acet ic acid . I n both cases th e st on e shou ld be w ell wash ed

,

dried, an d th en coat ed with dissolved l i thographic tu sch or au tograph ic ink . The greasy su bstan ces of these m aterial s pen e tratein to t h e su rfaces of th e ston e that are laid bare , an d firm ly adh ere .

Wh en t h e tu sch or ink i s com ple tely dry th e ston e is wash ed w ithtu rpen t in e , inked u p , an d on e n ow has a n egat ive im age from th e

su bj ect in qu est ion ,which sh ow s all th e origin al prin t in g places in

wh i te an d al l wh i t e places black .

Th e process of preparin g su ch n egative prin ts by t h e u se ofbich rom ated gelatin e papers i s m u ch sim pler.

A sheet of gelat in ized paper i s sen sit ized for this pu rpose on a5 per cen t . bath of potassium bich rom ate, squ eegeed to a sh eet ofplat e-glass and w ell dried , and on thi s i s m ade w ith black ink

,

wh i ch i s very opaqu e, in the dark or in gasl ight , a sh arp cleanprin t . Th is prin t i s then laid on a flat table

,u n der a sh eet of

plate-glass,so that it can n ot rol l u p , an d exposed t o th e light for

from five to thirty m inu t es . A lon g exposu re rarely does h arm in

su c h cases, as the good opaqu e bl ack ink a llow s n o rays of lightto pass th rough to th ose places w h ich lat er shou ld prin t wh ite .T h e n ext m an ipu l at ion i s t h e dev elopm en t an d inking u p , which

1s don e as- in ordin ary pho to-lithography. 1 11 th i s operation al l

84 PHO'

I‘

O-L ITHOG RA PHY.

those places which w ere n o t covered u p by the prin t ing w ill tak ethe developin g ink ; o n th e o ther hand, th ose places where t h e impression was w il l wash o u t clean and whi te . Th e prin t hasassum ed th e appearan ce of a ph otographic posi ti ve . Th e prin t i sn ow t reat ed like any oth er ph oto-l ith ograph i c prin t, an d fin allytran sferred t o a ston e or zin c plat e . Th is m eth od i s dis tingu i shedby its sim plicity and safety ; it has al so the advan tage th at anydesired prin t ing subj ect can be directly tran sferred in n egativeform t o a zin c plate for reli ef e tching, wh ich o therwi se cou ld on lyb e don e by prelim inary tran sfer t o ston e and subsequ en t tran sferto zin c .

2 . PHOTO-A UTOGRAPHY.

D RAWING WITH AUTOGRA PHIC INK OR LITHOGRA PHIC CHALK ON A

CYA NOTYPE , SA LT E D OR OTH E R PRINT FROM A PHOTOGRAPHIC

NE GAT I V E OR POSITI V E .

By au tograph y w e u n derstan d that m ethod of reprodu ction bywhich any writ in g or drawing i s m ade o n a prep ared or n o t prepared paper w ith greasy ink , t u sch o r chalk, which is subsequ en tlyt ran sferred to ston e or zinc for prin ting, or to zin c pl ates for reliefe tchin g.

A u tographic drawing papers difie r for the differen t pu rposes,

and for writing an d sim ple lin e drawings sm ooth hard post paperis u sed, an d l in ed tran sfer paper for fin e p en or chalk draw ings .The latter are prepared com m ercially by A ngerer and G esch l .

V ery beau tifu l grain ed draw ings c an also be m ade for tran sfer onpyram idal grain paper . The proof for su ch draw in gs i s u su allydon e w ith lead pen cil or re d chalk, or it m ay also be m ade on a

gelatin e proof .I n order t o obtain fu l ly and com pletely the character an d correct

reprodu ction of t h e drawing, w ith ou t special expen se of artistich elp

,it i s advisable t o u se a photographic prin t as proof. It

Sh ou ld be n oted th at for p e n drawing o n sm ooth pape r w ith greasyt u sch or ink, for chalk drawin gs o n a prepared grain ed paper don eas previou sly m en t ion ed , w i th greasy lithograph ic ch alk, t h edraw in g sh ou ld be tran sferred direct t o zin c or ston e in order t osave h aving to m ake subsequ en tly a photographic prin t .If a pen cil

,red crayon , or other proof is u sed for an au t ographic

draw ing on paper w ith the idea of tran sferring it direct t o st on eo r zin c , a su itable photographic prin t m ay also be u sed on su itablepaper w ith ou t any disadvan tages .For t h e prin ts all photographic papers w ith ou t glaze, su ch as

o rdin ary plain salted paper, E astm an’s posit ive brom ide paper

,

an d oth ers, m ay gen erally be u sed , Glossy or album en ized papersare n o t su itable for this, as th e ink ru n s, and does n ot form solidcl ean l in es .

P AIO'

l‘

O-A UTOG RA PH Y. 85

The best of all how ever, is cyan otype paper, as even with verydeep prin t ing it keeps th e de tail s in th e shadows open

, an d on .

accoun t of its bl u e t on es i s m ore su itable for t h e subsequ en tdrawing w ith black t u sch . Wh en ,

h owever, p ru ssI at e paper

is n o t h andy, and subj ec ts w ith fewer sh adow s and l es s detail sare to be treated, any of the other papers above m en t ion ed m ayb e u sed .

If ferro pru ssiat e paper i s to be u sed,the sam e m ay be prepared

as recom m ended on p . 23.

The so called sal ted or plain paper is prepared as follow sA sheet of wel l-Sized post paper i s first bathed in a solu tionof

Ordin ary sal t 1 partWater 25 parts

an d then sen sitized in a solu tion of s ilver n itrate 1 12. It i sprin t ed t ill the prin t h as assum ed a fairly fu l l brown ton e

,an d al l

t h e detail s in'

th e Shadow s are w el l prin ted ou t . I t shou ld thenbe ton ed in the following t on ing bath 1

D i still ed waterSodium acetate (twice fu sed)Solu tion of gol d chloride (1

til l the prin t has assum ed a deep dark brown ton e . I t shou ldthen be fixed in a solu tion of sodium hyposu lph ite

,1 : 15 . It

shou ld be prin ted rat h er deep, as in ton ing an d fixing th e im age .

loses m depth . It i s m oreover u n n ecessary in thi s case to m akea beau tifu l prin t ; the chief thin g i s on ly that al l detail s of th eim age Shou ld be clearly seen . Th e prin t i s then wel l wash edin frequ en t chan ges of water an d then dried.

The prin t on E astm an’s brom ide paper i s prepared as follow sR ed light m u st be u sed . It shou ld be prin ted by an ordin ary

gas flam e at a distan ce of abou t 50-80 cm . to 36 in s .) for 1t o 20 sec on ds, according to the den sity of the n egative . Hereagain a t echn ically perfect prin t n eed n o t be arrived at

,b u t on e

which con t ain s all th e detail s very clear. Un der a good tran sparen t n egat ive a u sefu l im age for t h e artist w i ll be ob tain ed w ithabou t two secon ds’exposu re .

The developer is com posed of two solu tion s

(A . W aterN eu tral oxalat e

.

of potash

(B .) W aterSu lph ate of ironCon cen trated sulphu ric acidOr glacial acetic acid .

Th ree parts of solu tion A a nd on e part of solu tionB shou ld b e

86 PHOTO-LI THOGRA PHY.

m ixed toge ther. A s soon as th e shadows have attain ed the desiredton e , th e prin t s Sho uld b e place d in seve ral fresh baths of

Water 200 c cm .

A cet ic acid l drachm .

Sat . sol . alum 50 g.

and then washed and fixed in a bath o f

Water 50 c cm .

Sodium 10 g.

for abou t t e n m inu tes . Then well wash e d and dried .

For p e n drawings all no t gel atin ized or alb um en ized prin tingp ap e rs m ay b e u sed as already m en tion ed . Th e chief thing is t h att h e paper shou ld b e we ll-sized and of good firm tex t ure . If p repared

grain paper i s u sed, which i s provided with a film of chalk,kaolin

,

or any o the r white co lo uring m atte r c om bin ed w ith gelat in e , andon which film t h e grain is impre sse d, o n ly pru ssiate prin ts can b eu se d. Th e paper is sen sit ized as p re vio usly described , on ly it isadvisable n o t t o leave it

,

to o long in the solu tion s, o r e l se the film

m ay becom e softe ne d. The film will also dissolve in hot water at

ab out 80° C.

Th e prin ts as soon as dry c an be u se d for draw ing on . On th e

grain papers the o u t lin e m ay be drawn with the p e n and be shadedw ith c halk, or it m ay be drawn with chalk o n ly . W ith u nprepared

p ape rs it i s advisable to coat them w ith a thin solu tion of boiledstarch , as then the tran sfer to zin c or ston e i s m ost exact. Th e

drawing m ay al so be left a long tim e withou t Spoiling. Th e c oat ‘

ing is perform ed w ith a pad dipped in to th e liqu id, which con sistsof on e p art o f fin e bo okbinder’s starch and fou r or five part s of

wate r, and p assed several tim es o ver th e prin t .The drawings ought o n ly to b e don e w ith greasy lith ographic

tu sch or chalk or au tograp h ic‘

ink, which con sists prin cipally of

greasy m aterial s and lampblack . For p e n drawin gs hard pen sshou ld be u se d, and care m u st be taken to m ake thick strokes .On ly a little tu sch or ink ought to be taken in to th e p e n ,

so that itdoes n o t ru n ou t , and thu s clean , Sharp lin es be obtain ed. If thisb e observed very close Shadings and cross lin es c an be produ cedc le an and n eat .Whe n th e drawing is fin ishe d and the tu sch or ink has becom e

dry th e sam e Shou ld be laid between dam p b lotting-paper, and

m eanwhile a clean ground, and dry pum iced ston e worked in th epress and th e pressu re correct ly adju sted . A S soon as the drawing h as becom e m oderately dam p righ t through , and the paper feelssoft witho ut being we t , it shou ld be laid w ith th e im age down

wards on the Ston e and tran sferred to the sam e with stron gpre ssure . A fter repeated working the paper w il l adhere firm ly t ot h e stone . I n order to loosen it the s ton e Shou ld be covered withhot water o f abou t 80° C ., when the film w il l di ssolve and t h e

p aper be com e qu ite free. A ny e xert ion of force m u st in this

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88 1 1 11OTo -L ITHOG RA rn Y.

T h e ston e i s n ow, according t o the sen si ti ven ess of th e film and

th e s tren gth of th e l igh t , exposed for from fifteen m in u t es t o twoh ou rs . Over-prin tin g

,if it i s n o t very exorbi tan t

,does n o t do any

h arm w ith t h e stronger letters or li nes o n accou n t of th e goodcover ing . W ith v ery fin e l in es , h owever, m ore care m u st be t aken .

If t h ere i s any doubt as t o th e length of th e exposu re a test m ay bem ade at o n e corn er of th e plate wi t h a p ad dipped in rect ifiedt u rpen t in e . W hen th e asph al t will n o longer dissolve th e exposu rem ay b e discon t in u ed. Wi th som e experien ce th e photom et er m ayalso be u sed .

Th en t h e w h ol e su rface sh ou ld be wash ed with rect ified t u rpent in e and a pad of c ot ton wool

,wh en t h e ink lying u nder th e bron ze

,

t h at is,t h e lin es wh ere t h e asph alt h as been prot ect ed from th e

act ion of light dissol ve, and th e su rfac e of th e st on e appears . Th e

rest of t h e asph alt film has becom e in soluble from t h e action of

light,and n ow form s th e etching-ground for the reversed n egative

im age o n th e surface of t h e s ton e .

W h en th e ston e has been w ell wash ed w ith w ater it m ay b e

etched, wh ich i s don e w ith glacial acet ic acid two part s, wat er 100

W h en there are any fin e l in es in the drawing t h e et ch in g i s int e rru p t e d a t t h e e nd of two m in u tes , an d th ey Sh ou ld th en becovered w ith t u sch ,

an d then when th e t u sch is dry th e otherpart s are fu rther etched for a longer or Sh ort er t im e ac cording t oth e degree of fin en ess . I n any case th e tim e of etching shou ldn o t exceed five m in u tes . Th e ston e i s allowed to dry and thencoated w ith a solu t ion of tu sch or lin seed oil , wh i ch pen etrat esin t o the etch ed parts and m akes them capabl e of taking ink .

A fter abou t t e n m in u tes the whole s ton e sh ou ld be wash ed w itht u rpen tin e or ben zole , by wh ich t h e etch ing grou nd i s rem oved

,

when t h e ston e i s inked u p like an ordinary gravu re .

In t h i s w ay i s obtain ed a ston e w ith deep etched drawing,

which according to the blocking con tain s th e t it l es , the rivers orroadways , and from which subseq uen t ly the n ecessary gravu res .

c an be t aken . This ston e can eith er be u sed for direct prin tingo r it m ay be u sed as an origin al ston e from which th e n ecessaryt ran sfer can be m ade .The sam e process m ay also be m ade for in taglio prin ting plates

o n zin c or copper, on ly then th e etching m u st be don e w ith n itricacid or ferric chloride .

In stead of th e t ran sfer on the light sen sitive film, a draw ing 011

t ran sparen t paper m ay be u sed, or a ph otograph ic tran sparen cy .

The exposu re in th i s case , as the opaqu e ink and bron ze powderare n o t u sed, m u st be very carefu lly est im ated .

Th e advan tage of this process i s t h at an in taglio printingsu rface m ay be obtain ed so that engraving is en tirely or part iallyavoided, an d that this prin ting surface m ay be u sed as an originalfrom which th e reprodu ction s are m ade .

SCRA P E R BOA RD S . 89

SCRA PE R BOARD S, MANUFACTURE D BY A UG E RE R G OSCHL,

V 1E NNA .

No . 6 .— A white scraper board prin ted w ith black lin es . There

are 40 black and 40 wh ite l in es t o t h e cen t im etre th e rat ioof black t o whi t e is as 1 2. A t righ t angles t o the black lin esim pressed lin es are arranged, of wh ich 37 are depressed and 37

raised u p t o th e squ are cen t im etre .

N o . 7 .— Th i s i s pract ically the sam e as No . 6

,on ly th at the lin es

are sligh t ly less in n um ber,n am ely , 35 black and 35 whit e and 26

im pressed l in es in equ al areas to N o . 6 .

N o . 8 .— Th iS con tain s do t s in st ead of lin es , both black and im

pressed ; th ere are black dots at regu l ar in t ervals , an d 961im pressed do t s t o the sq uare c en t im e tre .

N o . 9 i s a sm ooth scraper board .

N o s. 10 and 1 1 .— Th ese are im pressed with straigh t l in es in th e

proportion of 1 1 . W i th No . 10 th ere are 27 lin es , in No l l

37 l ines to th e c en tim e tre .

N o s . 12 an d 13 .— Th ese are im pressed with lin es at righ t angles

t o o n e an other, so that regu l ar sq u ares are form ed . N o . 1 1 con tain s730, No . 12, sq uares in every squ are cen tim etre.

I N D E X .

A c id, A c e tic G alls,T inctu re o f

C itric G e latin iz ing Pape r 1

G allic G en e ra l N o te s o n Pho to -lith o

Hydro chloric graphyNitric 1 G o ld and Mercury lii te nsifie rOxa lic 1 a G re asy D rawing Mate rials

Ph o sph o ric G um A rab ic

Sulph uric

A c tio n o f Lin e ature . Ha lf-to ne , Breaking up

A lbe rt’s Ph o to -lith o Paper Ph o to -lith o graphy

A lbum e n Proc e s s He b e n spe rgc r’s Proc e ss

A nge rer 81 G esch l Hub l’s Hydro q uin o ne Inte nsi

A sphalt fier

Proc e ss lso E m u lsio n

Husnik’s Hu sn ik

’s A sp h alt

V ale n ta’s Ph o to -lith o Pape r

A u to graph ic Ink Hydro q uino ne D e ve lo per

A u to typyNegative

Barto s’Pro ce ss 20 , 77Behaviour of A sphalt o n Sto n e

Cadm ium In te nsificatio n

Chrom a te Salts

Coating th e Stone

Co ld Me lt ing Proc e ss

Co rre c ring Negative s

Cyano type Paper

Ble ach ingLem erc ier and Lerebo urs

D ark Ro om,T h e Line D rawings

D e ep-e tch ing Pro ce ss Lith o Chalk

,Hard

D eve lop er So ft

D e ve lo ping Ink Sto n e

D irec t Prin ting Lith ogra vu re

T ransfer Lith o -He liograxu re

D istance of Lineature Lithography, T h ec ry o f

D rawing o n Blue Prints

Pre pare d Pape r Making D irect Nega tive s

Mungo , Po n to n

E berle’s Pro c e ss

E ckste in’s Pro c e ss N egative fo r Ph o to -lith o

E le c tric Lam p s T ran sfe r with Paper

E tch ing th e Sto ne N egre

Nic eph o re , Nie’

pc e

Failure s in T ran sfers

Fixing Ore ll and Fussli Pro ce ss 20, 75

Fox T albo t

Franz’s Paper Ph o to -A utography

Indirec t T ransfer

Inking u p and D eve lo pingIn te nsifica tio n .

In te nsifie r,Le ad

Me rc uryMe to l

Silve r

Uranium

Iodized Co llo dio nIsoc h rom a tic E m u lsion , A lb e rt

Hubl

P AG EPh o to-Lith o T ran sfe r 5 7 Sen sitizing Pap e rPh o tom e ter 5 1 Silver Bath

Po ite i in 1 7 Stripping N egatives

Prism 44 Studio,T h e

Prin ting 6 2

o n Bich rom ated G e latin e 50 T u sch

Pyram idal G rain Paper 2 6

V ale n ta’s A sph alt

Re produc tio n o f Prin ts

Siz e o f Wa te rho u se’s A rrowro o t Pro c e ss 66.

Reversed N egative s W e z e l Naum ann 75

Sach e r’s Fish -

glue Pro c e ss Zinc Plat e s

Scam o n i'

s Pro c e ss

Sc rap er Bo ards

Sc haufi'

e le n Co .

Month ly , Price 6d? Post Free , 8d. PerA nnum , post free, 8]

Th e on ly j ournal sp ecially devot ed t o th e int erests of Ph oto-mechanical

workers.

A P h e n o m e n a l S u c c e s s .

Mr. A LLA N W. SE WA‘

RD , o f Mon t c lair, N .J say s A lth o’an o ld p ro ce ss

-worker IW 111 n o t do wit h ou t t h e Pao c ass PHOTOGRA M .

”

D r. J . H . SM I TH, o f Zu rich , say s“ I am p le ased t o find y ou are bringing o u t a.

PROCE SS PHOTOG RA M . I h ave n o doubt i t will b e a su c ce ss .

”

Mr. JOHN CUMM I NGS, of A lloa, N .B., a be gin n e r in p ro c e ss-work , say s Yourm agazin e is sp len d id .

”

L IM IT E D IS S U E .

Ord e r at on c e from an y N ew sag e n t or Ph o t o Mat e rial D e al e r, or at p ost

fre e p ri c e s from t h e Pu b l ish e rs.

M o n t h ly , P r ic e 3 d . P o s t F r e e , 4 2-d .

D E VOTE D TO PHOTOGRA PH I C WORK .

E D ITO RS

H . SNOWD E N WARD . CA THARINE WE E D WARD .

P E RM A N E NT S TA FF

CHARLE S W . G AMBLE . SCHRIFTFUHRE R.

W. E THE LBE RT H E NRY, C E . W.T .WHI TE HE A D .

Has t h e l arg e st c ircu lat ion o f an y Ph o t ograp h ic Jou rn al . Con t ain s e ac h

m on t h su p p l em e n t s o f gre at valu e t o p h o t ograp h ers an d p ro c e ss m en.

Far and away ah ead o f its p h o tograp h ic c o n t em p orarie s .—0p tic ian .

Th e PHOTOGRA M sm acks o f sm art n e ss. I s sm art ly e d ite d . exc e lle n t ly arranged ,and ve ry tast e fu l in ty p e and grap h ic d re ss, as we l l as be in g m u c h be t t e r p rin t e d ando n be t t e r p ap e r t h an any o f t h e p h o tograp h ic jo urnals o f h om e p rodu c t ion .

— Th¢B ret t

'

s/t Lithograp her .

“ Sim p ly invaluable t o all wh o are in t e re sted in p h o tograp h y .—B ook and N ews

T rades G aze tte .

“ Th e P HOTOGRA M is a rem arkable p rodu c t ion , bo th in le t t e rp re ss and illu st rat ion s.—é

‘

h efi ie ld Te legraph .

Th e first vo lum e o f t h e PHOTOGRA M h as be en o ne of rem arkable exc e llen c e , bo th i n

it s m at t e r an d illu st rat ion s. —Liverpoo l Courier.“I t is a m arve l .

'

h igh ly in te re st in g m at t e r, an d filled with illu strat io n s. Th esty le , ge t up , an d p rin t ing are all h igh c lass.

” — l e P hotograp h er.

D AWBARN WARD ,Limit ed

,6 , m axim um A V E NUE ,

LOND ON,

Pric e I s . n e t t . P ost Fre e

1s . 6d .

I n A m e rica an d ab ro ad .

P o st Fre e 2s . o r 50 c e n t s .

R eady a bou t Oc t ober

20th .

A P I OTORI A L A ND LI TE RARY RE CORD

O f t h e B e s t P h o t o g rap h i c W o rk o f t h e Y e ar .

Arrangea by the E ditors and Of

THE PHOTOGRAM.

To b e followed n ext y ear b y Ph otograms of ’96 .

Ph o t o gram s o f ’95 aim s t o re p re sen t m odern ph o t ograp h y as“Royal A cadem y P ic

t ure s,”

P ic ture s of th e Ye ar , &c ..rep re sen t th e arts of p ain t ing and scu lp t ure .

T h e Wo rk c onsist s of 96 p ages, sup er-royal 8vo (9§ by and is p rint ed on h eavy art

p rin t ing”

p ap er.

T h e I l lu st ra t i on s are th e fin e st p ossible p h ot o-m ech an ical (h alf-t one) rep rodu c tion s,

and are m ade b y th e M E I SE NB A CH Co ., We st N orwood .

Th ere are abo u t th irty ful l-p age rep roduc tion s, and th e sam e num ber of sm aller size s,m ost ly h alf-p age , as we ll as

F o u r Ch em igrap h Su p p l em e n t s , p rin t ed b y t h e NA TI ONA L CH E M IGRA PH Co o f

St . Lou is, N ew Y ork , and Ch icago , and m ount ed on h andsom e boards. Th e y rep re sent

t h e four p rin cip al im itat ion s o f p ure p h o tograph y b y p h o‘o -m e ch an ical p roc e ss, and as th e

work o f th e N A T ION A L CH E M I GRA PH Co . h as n ot be e n p ublish ed in E ngland, will b e a re ve la

t ion t o p h o tograp h ers and p h o to -m ech an ical work ers alike , of t h e lat est p ossibilit ie s in“

p roc ess”

work . I t will b e qu ite im p ossible t o rep e at th e se su pp lem ent s, and t h e refore

im p ossible t o sup p ly any cop ie s th at m ay b e dem an ded aft er th e first edition is exh au st e d.

T h e L i t e rary P o rt io n 0° th e work

'

in cludes critic al n o tice s o f th e two gre at British

Ph o t ograph ic E xh ibit ion s , and sp e c ial art icle s on th e work o f th e ye ar in th e E nglish-sp e aking

c oun t rie s and colon ie s b y som e o f th e best—q ualified writ ers in each c oun t ry .

‘

A m ongst th em

BRI T I SH I SLE S — G LE E SON WH I TE , assist ed by th e stafi of Th e P h otogram .

UN ITE D STA TE S z—A LF R E D STI E GLITZ , E dit or o f Th e A m e rican A ma teur Ph otograp h e r .

CANA D A z— A . M . CUNN INGHA M , Pre side n t of Th e Ph ot ograp h ic A sso ciat ion of Canada .

T h e Brit ish E xh ib it ion s of Th e Royal Ph o t ograp h ic Soc ie ty and Th e Salon h ave su p

p lied m o st o f th e originals for rep roduc t ion , b u t som e of th e gem s o f th e p rovin c ial exh ibit io ns

are also In cluded .

N o u -E xh ib i t e d P ic t u re s are rep re se n t ed as far as p ossible , for th e aim is t o em brace

t h e wh ole fie ld of t h e y e ar’s work .

A m e r l c an , Co l on ial , & c .,work 13 rep resen t ed by a few typ ical p ictu re s, select ed b y th e

gentlem e nwh o sup p ly t h e m at t er de aling wit h t h e work of th e variou s c oun t rie s .

T h e S c ie n t ifi c an d P rac t ic al ap p licat ion s ofph ot ograp h y are n o t ignored , th ough th e

bu lk of th e sp ac e is devot ed t o art works. Som e of th e lat e st ach ievem en ts in astron om y ,

m icrosc op y , &c ., are illu strat ed by re p rodu ction s of th e fin est recen t Work .

T h e E di t io n is L im i t e d t o c op ie s .

Order early . Ready Oct ob er 2oth .

Publish ed for “ THE PHOTOGRAM Ltd.

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N EW YORK z— SPON 8: CH AMBE RLA I N, 12, Cort landt Stre et

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Ce ram ic an d Me t al l ic su rfac e s.

W. E THELBERTHE NRY, C.E ., andH. SNOWD ENWARD

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Cloth Gilt. Pric e 128 . 6d. ne t . Post fre e , 13s .

A CompleteHandbook of the T erms, Processes, F ormulae, and Appliances available

for P hotography , arranged in Cy clope dic F orm for ready reference.

BY E D WA RD L. W I LSON , PH .D .,

E ditor o f “ Wilso n’s Pho tograph ic Maga zin e A uth o r o f “ Wilso n’

s Ph o to

graph ic s,“ Wilso n’

s Q uarter Ce ntury in Pho tography, Ph o tograph ic

Mo sa ics, & c .

o f al l P h ot ograp h ic D e al e rs or Books e l l e rs ,

N DA

D A W B A R N 80 W A R D, L t d . ,

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HThe A r t and Practice o f In terior Pho tography ,

“ Photography

for A rchitec t s,

” “ Photography applied t o th e Microscope ,”

A n

In troduction to th e Study o f th e'

D iatomaceae,”

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P o s t a g e 2 d .

Wit h axp asu r e an d o t h e r 94521 619 3 .

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Of all Ph otograph ic D ealers and Bookse llers or

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PHOTOLITHOGRAPH FROM A PEN AND lNK SKETCH.

FROM A N E TCHING PUB LI SHE D BY E . A UMULLE R IN MUN I CH .

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