media problems 3. media problems (may 1985) characteristics

MEDIA PROBLEMS

3. Media Problems (May 1985)

Characteristics inherent in graphic media which create problems:in the media or in the relationship between media and support; attime of application or as the object ages; or pose special problemsduring conservation treatment.

3.1. Purpose: To identify potential problems so that treatmentand storage and exhibition conditions can be limited ormodified so that media are not altered. To identify problemsto help determine treatment methods.

3.2. Factors to Consider

3.2.1. Inherent physical characteristics of media:

A. ColorB. Surface: glossy or matte, compacted or fluffyC. Topography: raised or flat, thick or thinD. Integrity: fixed or loose, flexible or

brittle (tented, flaking, etc.)

3.2.2. Relation of media to support:

A. Media may discolor or degrade paper (e.g. oilpaint, iron gall ink, printing ink, titaniumdioxide, copper greens, zinc white).

B. Media may protect paper: lead and calciumwhites; opaque pigments

C. Is media well adhered to paper support?(or to ground or underlying layers)

3.2.3. Alteration of media upon aging

A. Desiccation of binders: watercolor, gouache,tempera, distemper, printers inks

B. Oxidation of oils, waxes

C. Color changes, fading and other alterations mayoccur without the influence of an outside agent,e.g. fading of iron gall ink; felt tip pen inks.

D. Materials in combination with each other maycause changes over time, e.g. lead and arseniccontaining pigments in Islamic miniatures. (M.C.)

(3. Media Problems p.2)

3.2.4. Sensitivity of media to environment:

A. Light: e.g. natural organic pigments, gamboge,cochineal lakes, indigo, carmine, vermillion;some pastels. Inorganic pigments are much lesssusceptible.

B. Humidity

C. Pollution: e.g. red lead, white lead, naplesyellow, smalt

D. Heat: e.g. wax

3.2.5. Chemical sensitivity to

A. pH

1. Acidity: (calcium carbonate, red lead,ultramarine). "Litmus" reactions seen inwatercolors which have been in contact withacidic mats.

2. Alkalinity: In most cases it is organicpigments that change colour on deacidifica-tion due to changes in their molecular andelectronic structure (logwood, carthamine,gamboge, litmus, tumeric, cochineal)(Daniels). (Also, Prussian blue, madder,chrome green, Hookers green, yellow lake, vandyke brown, gamboge, some pigments in Currierand Ives prints).

B . Oxidation/reduction: indigo, Prussian blue(develops irridescence)

C . Heavy metal ions (some transition metalsin particular, e.g. Co, Cu, Fe, Mn, Zn) whichmay catalyze degradation of cellulose inpresence of oxygen and moisture (Mairinger et.al.-p.181) Specific pigments: e.g. Ti02, ZnS,ZnO, copper greens.

3.2.6. Potential alteration of media during handling:flexing support, brushing, touching or coveringsurface.

Note: a uniform surface "abrasion" or polishingmay be a positive sign of the good condition andnormal aging of old master prints and drawings kepthistorically in albums. (M.C.)


3.2.7. Potential alteration of media during conservation treatment:Effect of moisture, solvents, consolidants, buffers,weight and pressure, heat, air currents, staticcharge, lining.

Treatment may affect the chemical structure of themedia without causing visible alteration at the timeof treatment.

3.3. Materials and equipment for treatment of media problems.

See specific catalogue categories as referenced below.

Consolidation/Fixing/Facing (#23)Treating friable or soluble media

Matting and Framing (#40)Special considerations for friable materials

Materials/Tools/Equipment (#47)Suction table (47.3.1)Electrostatic plate


3.4. Media Problems

Media problems will be discussed in terms of generalproblems, specific problems, suggested or ill-advisedtreatments, and/or traditional and contemporary formulationsand applications.

3.4.1. Drawing media

Some potential friability with most drawing media.Range from slight to marked friability, withsensitivity to abrasion or to any material capableof generating or holding static charge, e.g.plexiglas/ polyester film.

Dusting of soft pencil or other friable drawing mediaover the surface of a drawing often creates a grimeyor smudged appearance and poses the problem ofwhether or not to dry clean. Careful considerationshould be given to possible creation of "halo"effects around drawing lines before undertaking suchtreatment. (See: 17. Dry Cleaning)

A. Metal Point (See: Ellis; Harding)

1. Medium: An anticipated and desirabletarnishing of the metal media to theircharacteristic colors.

2. Ground:

a. Friable and easily abraded (surfaceshould be carefully protected)

b. Absorbs oils and fingerprints

c. Softens and stains readily withmoisture

d. Susceptible to cracking (See: 3.4.3.watercolor - friability, flaking,etc.)

3. Treatment Caution with oxidative bleaches - can causediscoloration of the media.

Reductive bleaches may cuase changes intarnished (naturally oxidized) media.


B. Pencil

1. Graphite Pronounced reflectivity of natural graphitecould be adversely affected by wet treatment(?) (M.C.)

2. Indelible pencil

a. Visually is virtually identical tographite pencil. Purple component bleedsout with slight moisture application andmay also be solvent (acetone) sensitive.

b. Seen in German and Central European works,often in signatures. Some suggestion that itwas used during WWII when graphite was inshort supply. Also appears in some Picassosignatures, so caution with pencilsignatures on contemporary prints.

c. Treatment: Test pencil drawings andsignatures separately. Will notnecessarily bleed with brief testingwith water.

Colored dye may be pH sensitive andconservator can possibly minimizedisfiguring aspect of bleeding dye bylocally applying buffered solution.

Encountered in a sketch by Dufy. Intreatment it turned purple but did not bleedin acetone. Conservator continued washwith a stronger solvent; rinsed withacetone. Purple was removed except infour heaviest downstrokes. Theselessened with local application ofmethanol.

d. "Mephisto" is one current brand name.

3. Carbon pencil


4. Colored pencil

a. May be fugitive

b. May be water soluble (e.g. prismcolor).If watercolor pencils have been blendedinto a design by applying water, caremust be taken not to soften hardedges of lines not treated with water.E.g. Many Jackson Pollack drawings wereonly partially treated with water by theartist to make washes. (M.E.)

c. Often sensitive to or soluble in organicsolvents.

5. Watercolor pencil

Looks like regular colored pencil, butfeathers even in slight vapor as would beused for flattening. Used dry by JacksonPollack along with regular colored pencils.Each color must be checked prior totreatment. (M.E.)

C. Charcoal

1. Extreme friability makes any treatmentproblematic. In addition, a drawing may beonly partially fixed, the lower layer beingfixed before the last application ofcharcoal. Must test for fixing throughoutthe drawing.

2. Resinous or sooty charcoals may be solublein solvents.

3. Homemade/manufactured charcoals may have dyeadditives.


D. Chalks

1. Natural chalks

a. White: calcium carbonate (see watercolorbelow), lead carbonate, calcium sulphate,etc.

b. Black

c. Red: (iron oxide) Not susceptible tofading. May darken and/or dissolve uponwetting.

Water and some organic solvents willdisperse smallest particles, move outbinder yielding darker, cooler hue.(D.D.M.)

Turns yellowish orange on abrasion.

2. Fabricated chalks and pastels

a. Friability: Greatest natural mediafriability is encountered in pastels andcharcoal. While pastels may be fixed bythe artist, fixing is not generallyrecommended as a conservation treatmentas it can alter the appearance of themedia. (See cautions for drawing mediabelow).

b. Binder: Gum tragacanth, the traditionalbinder, is attractive to insects andpromotes mold growth. Cellulose ethersare now used instead.

c. Sensitivity to light: e.g. Degas used abright red violet; red component is alake (morphology under crossed polars);this fades leaving deep cobalt blue onsurface. (P.D.)

3. Oil Pastels Can be damaging to paper due to oil content.Can be sensitive to organic solvents for thesame reason.


E. Waxy Crayons ("Crayon" also an early term for chalk andpastel).

Likely solubility or softening of waxy binders inorganic solvents. See: 19. Solvent Treatments.

F. Litho Crayon May be solvent sensitive.

G. China Marker Red, black, white.May be solvent sensitive, soluble.

H. Cautions for drawing media duringConservation Treatment

See Paper Conservation Catalogue categoriesreferenced below:

Washing (#18):-float washing: potential compaction,

movement of loose particles.-solubility of one component of a mixed

pigment undetected during testing (e.g.gamboge in a green)

Consolidation/ Fixing/Facing(#23):

Fixatives applied to reduce naturalfriablity of media, especially pastels andcharcoal. Generally not recommendedconservation treatment for drawing media,expecially pastels, as application will alterthe artist's aesthetic. Can causecompaction/ saturation of media and blendingof colors, possibly altering color value andcharacteristic "fluffy" surface.

Fixatives may be absorbed into the paper andcause (J.K.):-discoloration and degradation products to be

held in sheet-haloing-uneven aging of paper.


Backing Removal (#24):Potential transfer if object placed faceagainst surface (particularly pastel). Ifsuch treatment is necessary with friabledrawing media place recto against smoothrelatively frictionless (glass, glassine,silicone release) and weight to preventmovement. Repeated testing essential intreatment, as pressure, steam or moistureapplied to verso may cause unanticipatedtransfer of media.

If possible treat vertically as with a Dutchstrainer (J.K.)

Environment (#43)

Exhibition/Storage (#44)

Matting and Framing (#40)Considerations for friable materials

Transportation/Packing (#45)

Materials/Tools/Equipment (#47)

Suction table (47.3.1):Some conservators are wary of possiblecompaction of media or pulling of mediainto the paper, particularly fluffypastel. Possible problem of pullingsoluble media to the back of the artwork.

Electrostatic plate: (Blythe)Creates an electrostatic attractionbetween the pastel particles and theirsupport through the use of anelectrostatic stabilizing plate(elaborate....)Presented as an alternative to severalmethods of fixing which potentiallyalter the appearance of pastels.


3.4.2. Ink

A. Black carbon inks

1. India ink:Shellac binder soluble in alcohol.

2. Sumi or Indian black carbon inks:Very water soluble.

B. Brown inks Some brown inks are affected by hydrogenperoxide or other oxidizing agents. Necessitatesparticular caution when converting darkened leadwhites on brown ink drawings.

1. Iron gall Can also be categorized as a "black" ink, thecolor after initial application andatmospheric oxidation. Generally fades toreddish brown, often eventually to paleyellowish brown due to decomposition productsof carboxyphenolic acids which can no longercomplex with the traces of metallic oxidesremaining on the support (Talbot et. al.-p.1)

Note: Some inks are pale from the startdepending upon the recipe (J.K.)

a. May penetrate, deteriorate, corrodepaper support due to its acidity.No certain method for stopping orreversing its effect on paper. Weakestareas should be reinforced on verso withJapanese tissue. Extensive deteriorationmay warrant lining.

b. May fade (Talbot, et.al.-p.2)

1) Factors affecting fading

a) external factors: oxygen,humidity, light, pollution

b) internal factors: compositionof the ink, nature of the support

c) high pH in aqueousdeacidification can lightenlines, whether by fading or byincreasing solubility is unclear.(M.C.)


2) Methods of making faded iron gallink visible:

a) U.V. or I.R.

b) Regeneration: various solutionsto reintroduce color.

2. Bistre

3. Sepia

C. Colored Inks and Washes

Red inks are frequently extremely soluble anddifficult to consolidate sufficiently forwet treatment.

D. Writing inks (fountain pen inks)

May have solvent sensitive/ soluble somponents.

Blue/black writing inks (especially those used byElie Nadelman) have often faded to brown.Original color can be detected undermagnification where the edges of the black lineare blue, as wicked out by paper fibers. Verywater soluble. (M.E.)

E. Ballpoint pen inks

Extremely variable in makeup and reaction totreatment. The lubricant in the pen ink is anoil base material.

May have solvent soluble/ sensitive components.

Often soluble in alcohols. This factor may beuseful for removing or diminishing accessionnumbers written on artworks in ball point pen.

Some formulations are quite fugitive.

F. Felt tip pen inks

Most formulations are extremely fugitive evenwhen stored in the dark. Some recentformulations may be more stable.

May have solvent sensitive/ soluble components.


G. Cautions for drawing inks during conservationtreatment.


Washing (#18)

Solvent Treatments (#19)


3.4.3. Paints

A. Watercolor and gouache

May be fugitive, either fading or changingcolor, in the presence of light (also, oxygen andwater vapor) because of thinness of application,minimum of binder, and/or inclusion of dyes andother natural organic materials.

Often one component of a mixed pigment (e.g.gamboge in a green) will be more fugitive thanthe other, shifting the tonal balance of thepigment as it fades.

1 • Pigments: See "D" below.

2. Binders (gum arabic, vegetable gums, dextrin,tragacanth)"An understanding of specific pigment usageand pigment/binder relationships will aid theconservator in deciding whether a watercolorcan be washed and in what solution."(Cohn-AIC-p. 39)

a. Continued solubility or sensitivity to water:

1) Continued solubility has a great dealto do with whether watercolors weredrycake, moist cake or tube.Therefore, pre-nineteenth centurywatercolors are generally a lot lesssoluble, assuming the washes arethin. Thicker accents will besoluble. Later watercolors may bevery safe too, but each color must betested at its point of thickestapplication. pH changes canadversely affect solubility. (M.C.)

Rule of thumb: watecolors over 60years old tend to be less watersoluble.

2) "Folk art, such as Pa. DutchFraktur, where the home made paintwas pigments ground in cherry gum,remain so soluble (esp. redand yellow) it is arisk to even spray the painting withwater." (Weidner)

(3. Media Problems p. 14)

Primary documents also list otherbinders used in Frakturs and folkart. Extreme solubility of thesepigments is not necessarily the rule,and moisture can often be used aftercareful testing. (J.K.)

3) Treatment: Might humidify prior toaqueous treatment for more even andcomplete wetting of watercolors, andto ease the shock to the media.

b. Sensitivity to or solubility in organic solvents:

1) Watercolor pigments which are trulysoluble in water (as compared to"sensitive") may be highly solublein other polar solvents as well.

2) Thanka paintings: Yak fat is used asbinder can be sensitive to naptha andtoluene.

c. Friability, flaking, tenting.

Integrity and permanence of the paintlayer depend on the adhesiveness of thebinding gum, characteristics of the papersupport, thickness of the paint layer,and environmental influences.

1) "The most common cause of flakingpaint is dehydration of the bindingvehicle used in the original mixingof the paint. Binders such as egg,glue or gum can gradually lose theirability to hold the pigment particlestogether or to their support" (e.g.Islamic miniatures, medievalmanuscript illuminations, grounds ofmetal point drawings, tempera,gouache). (Ellis-p.31)

2) If paper surface is not sufficientlyabsorbent, paint adhesion may beincomplete or insecure. Also, thethinner the paper support, the moreit moves (e.g. paper with shortwoodpulp fibers), the smoother itssurface, the greater the possiblityof flaking.


3) If the paint layer is thick as ingouache, it will be brittle andinflexible and will tend to crackwith movement of the paper support.

4) Treatment: Even a stable watercolorcan have friable elements which arenot evident until aqueous treatmentis begun. Surface tension of thewater bath can pull off friablematerial. Suggestion that this canbe alleviated with the addition ofalcohol to the bath (approximately10% solution). Caution: the alcoholmay make float washing a bit moredifficult.

3. Masking agents

"Masking agents that establish areas ofreserved highlights through the principle ofwater repellency (as opposed to waterresistance, the principle of other maskingagents) are other substances that areaffected by organic solvents. Often theirpresence can be detected only through acareful examination in strong raking light,yet they should always be of concern, astheir removal could take with it residues offragmented color films." (Cohn-AIC-p.40)

B. Tempera

1. Often problems with cracking and flaking.

2. Specific artists: Andrew Wyeth oftendid not follow a recipe - problems withcracking and flaking in his works. PaulCadmus followed medieval recipe, and no suchproblems seem to occur. (M.E.)

C. Oil

1. Incompatible with paper support. Causesoxidation of the paper: degrading,discoloring, embrittling. A halo ofdiscoloration appears around the pigments,caused by oil which has bled out and oxidizedthe fibers. A heavily sized paper may besomewhat more resistant to the degradingeffects of oil.

Note: Some artists have sought the haloeffect, e.g. Picasso (C.B.)


2. Can become hard and brittle with age. Aspaper contracts and expands with temperatureand humidity fluctuations "if the paint isapplied to the paper too thickly there is agood chance the paint will become crackledand flake off. It is for this reason that itis often recommended that a thick oilpainting on paper be mounted on a rigidsupport." (Weidner)

3. Specific artists: Degas successfully usedoil paints which had been leached of much oftheir oil, "Peinture a l'essence," groundpigments in spirits. These works are oftenmistaken for gouache because of their mattesurface and "dry" look.

4. Paper can become sensitive to alkali. (J.K.)

5. Thymol softens oil binder.

6. Treatments for drawings severely weakened byoil medium: (Advisable to consult apainting conservator or, better yet, aPainting Conservation Catalogue).

a. Solid mounting

b. Lining with Japanese tissue. (Haneret.al .)

See: 23. Consolidation/Fixing/Facing;29. Lining and Mounting

D. Synthetics

1. Acrylics

a. Magna color: solvent based media(xylene)

b. Liquitex: water based media, but doesnot remain so when dry.

2. Alkyd resins3. Casein4. Synthetic laquers5. Nitrocellulose based products

a. Laquer (Agateen)b. Paint

6. Metallic paints and Phosphorescent paints


E. Pigments (Information on causes of pigment discolorationtaken in large part from paper by D. Evans. Seebibliography).

1. Whites

a. Chalk (whiting)(lime white)(calciumcarbonate):Acids released from papersupport when it is humidified or wettedby float washing may consume, diminishor discolor the white pigment.Tends to soften with water.

b. Lead white (flake white)(basic leadcarbonate):Generally darkens to gray, brown or blacklead sulphide when in contact withsulphide pigments (e.g. vermillion) orwhen exposed to hydrogen sulphide in apolluted atmosphere. This discolorationoccurs more readily in the presence ofmoisture and is favored by darkness.

May be oxidized back to a white pigment,lead sulphate, with dilute, slightlyalkaline hydrogen peroxide (aqueous orethereal).

Hydrogen peroxide for converting leadwhites should not be used in acidicsolution because remaining lead carbonatemay be consumed by the acid.

Occasionally it is observed thatconverted lead whites "appear" to revertto a gray state. It is likely thatinitially only a thin film of the pigmenthad darkened to the sulphide and had beenconverted to the sulphate duringtreatment, and that it is the remaininglead carbonate which has reacted withhydrogen sulphide to form more of thedarkened pigment.


Darkened lead whites cannot always besuccessfully converted to a whitepigment. Lead which which has gone"completely" black seems most resistant.Application of hydrogen peroxide as anoxidizing agent may only turn suchpigment pale gray, and at worst may makeit disappear.

Occasionally a yellow or salmon-coloredphase is seen. Such pigment seems readilyconverted to white with hydrogen peroxideapplication.

c. Lithopone (combination of barium and zincwhites). Can darken in the presenceof iron. (E. Sayer)

d. Zinc white (Chinese white)(zinc oxide):Photosensitizer - reacts photochemicallywith paper. Loses covering power due tohydrolysis by alkalis.

e. Titanium dioxide: Photosensitzer.

2. Reds

a. Natural Alizarin (madder lake) (organic):Purpurin component is quite fugitive.

b. Synthetic alizarin (from aluminum hydratetreated with alkali):Alkali sensitive.

c. Carmine: (cochineal) (organic):Discolors to a greenish grey or a faintsepia-like brown in sunlight.

d. Cadmium red (inorganic):Poisonous if ingested. Blackens inchemical reactions similar to those ofcadmium yellow.

e. Red lead (minium) (inorganic):Darkens to black or deep brown, sometimeswith a silvery sheen, when light causesformation of brown Pb02; can usehydrogen peroxide to convert darkenedsurface pigment to thin translucent filmof white sulphate which allows redbeneath to show through. (see white lead,above).


e. Vermillion (red mercuric sulphide)(redcinnabar) (inorganic):"...its easy redissolution, must beapproached with great circumspection ifwashing in water is contemplated astreatment." (Cohn-AIC-p.39-40)

May darken toward black with sunexposure, which promotes conversion tothe black enantimorph (meta- cinnabar).Darkening occurs more with artificialpigment. Some say that thisdiscoloration is reversible to a certainextent in the dark.

3. Yellows

a. Gamboge (organic):

1) A gum resin so is partially solublein alcohol and some other organicsolvents.

2) Is alkali sensitive. Discolors tored with alkali. Darkens withammonia fumes.

3) Fades in sunlight.

4) Its use in a watercolor may berevealed only after the closestexamination, for it was recommendednot only as a pigment but as a localvarnish, to intensify the tones ofdeep green and brown foliage areas,where its coloring effect would beinconsequential." (Cohn-AIC-p.40)

5) In 19th c. is often mixed withPrussian blue to produce a green.It may pass unnoticed in testingprior to treatment but may solubilizein solvent treatment, changing greento blue.

b. Yellow Lake (Quercitron Lake, Brown Pink)(organic):Fades to bluish gray or yellowish brownon contact with alkalis.


c. Indian Yellow (organic):Discolors to brown on decompositon byoxidation, hydrolysis.

d. Lead-tin yellow (inorganic):Discolors to grey, i.e. may revert towhite lead on long exposure to dampair.

Blackens to lead sulphide in presenceof hydrogen sulphide.

e. Orpiment (inorganic):Blackens when placed with coppercontaining pigments, forming black coppersulphide.

f. Naples Yellow (inorganic):Blackens or darkens in the presence ofsulphur compounds (in air or in otherpigments), or when in contact withmetallic iron, tin, pewter, zinc.

g. Turner's Patent Yellow (inorganic):Blackened by water and sunlight.

h. Chrome Yellow (inorganic):Turns green when mixed with colors oforganic origin: tendency towardsreduction, the loss of oxygen by itschromic constituent, by which the greenoxide of chromium is formed.

Darkens to dark brown or grey on reactionwith hydrogen sulphate in polluted air.

i. Barium Yellow (inorganic):Turns green on exposure to light due toformation of chromic oxide.

J . Cadmium Yellow (inorganic):Bleached by water and oxygen fromatmosphere due to formation of whitecadmium hydroxide.

Darkens when mixed with copper piments orwhen mixed with flake white, the lead ofthe latter takes a sulphur ion from thecadmium yellow, transforming it to blacklead sulphide.


k. Cobalt Yellow (aureolin) (inorganic):Discolors to brown or black when mixedwith indigo in presence of hydrogensulphide.

4. Greens

a. Copper greens Malachite (basic copper carbonate)Green verditer (manufactured basic copper

carbonate)Verdigris (copper acetate)Copper resinate (copper acetate or other

copper salt in resinous solution)

1) Degradative effects on paper("Kupferfrass") (verdigris, copperresinate)

a) Appearance: "During the firststage pigments seem to migrate tothe reverse of the paper supportgiving it a green appearance. Inthe following stage the paperbecomes brownish, first locallyat those places bearing the greenpigment; afterwards thedestruction spreads over widerareas. As the browningincreases, the green colordisappears gradually andin extreme cases cannot bedetected anywhere. Finallythe perforation of the papertakes place on account of itsincrease embrittlement."(Mairinger et. al.-p.181)

b ) Causes: "IRS studies concerningdegradative properties of somecopper compounds with cellulosegave indications for combinedinfluence of SO2 and sunlightwith wavelengths above 330-340nm." (Banik and Ponahol-p.1 )


c) Specific pigments: "Differenttypes of copper acetate showedno uniform behaviour but gavestronger effects than copperchloride, whereas malachite,schweinfurt green andcalcium-copper acetate wereproved to be inert, as far asthe present research work couldbe carried out." (Banik andPonahol - p.1)

2) Alteration in pigment hue:Discolorations ranging from smallshifts of hue to a complete changefrom green to brown or even toblack..." (Mairinger et. al.-p.180.See article for discussion ofchemical reactions).

3) Treatments

a) The literature mentions thatsoluble magnesium, calcium,cadmium salts inhibitdecomposition of cellulose byheavy metal ions. Tests byMairinger et. al indicate that"Magnesium seems to inhibitstrongly the degradation of thepaper carrier." Chelating andcomplexing agents might be usedfor the same purpose.(Mairinger et.al.-p.181)

-Question remains as to how muchmagnesium is needed.-Caution must be taken if thearea is very acidic, as alkalimay be injurious. (J.K.)

b) Locally treating degraded areawith alkaline solutions (See:20. Alkalization and Neutralization).

c) Buffered Japanese tissues placedbehind sensitive areas. (See:20. Alkalization and Neutralization).


b. Scheele's Green:Rapid fading, blackening due todecompostion by acids, presence of lead;also, blackening due to formation ofcopper sulphide in presence ofsulphur containing air.

c. Emerald Green:Turns brown or black in strong light,in presence of sulphur containing air orpigments, or when decomposed by acids orwarm alkalis.

d. Sap Green:Fades.

e. Hooker's Green (Prussian Blue andGamboge):Turns blue due to fading of gamboge.

f. Chrome Green (Prussian Blue and ChromeYellow):Turns blue in strong light, due todarkening of chrome yellow or because ofacids which dissolve lead chromate.

Turns dark orange in alkalis which effectthe decomposition of the Prussian Bluecomponent.

5. Blues

a. Indigo (organic):Vegetable coloring matter. May undergodiscoloration by reduction reactions.i.e. turns white when reduced by anyof several reducing agents to solubleindigo white, which is oxidized by air toinsoluble indigo blue. Also, bleached byhypochlorite solutions.

Fading or browning when decomposed byphotooxidation; fading increased bypresence of alum in the paper.

b. Logwood (organic):Used in 17th and early 18th c. to colorprints.Discolors to red.


c. Prussian blue (organic):Alkali sensitive may turn brown.Fades in strong light. Literaturementions that depth of blue will returnafter brief storage in the dark.

Treatment: some suggestion thatunanticipated browning of Prussian blueexposed to alkaline material duringtreatment might be reversed by exposureto mild acid, i.e. carbonic acid formedby carbon dioxide reacting withmoisture. In practice the materialmight be humidified/moistened andexposed to the air. (A.O.)

d. Ultramarine (natural andsynthetic)(inorganic):Turns pale greyish blue when decomposedby very weak acids and the presence ofsulphur dioxide."Acid sensitive." Will permanentlydecolorize, e.g. if a picture with a slatburn is treated with water, making theacid liquid. (M.C.)

e. Azurite (inorganic):Turns green by hydration.Blackened by warm alkalis or exposure tosulphur fumes.

f. Blue Verditer (inorganic):Turns green through loss of ammoniacomponent.

g. Smalt (inorganic):Turns pale greyish from exposure tomoisture and carbonic acid in air.

E. Cautions for paints during conservationtreatment.

See Paper Conservation Catalogue Categoriesreferenced below:


3.4.5. Miscellaneous media encountered in drawings andpaintings on paper.

A. Wax

Can be applied to paper in the form of drips(Jackson Pollack) or brushed on as resist (VictorBrauner). In both cases, it was observed thatthe paper below the wax darkened and becamebrittle. The same guidelines for painting in oilon paper apply to the use of wax. (M.E.)

Sargent used white wax resist pencil in somewatercolors. (M.C.)

B. Distemper

On early wallpaper may be insoluble butfriable. Particles may physically be moved bytouch or water. (J.K.)

Vuillard used dry pigments and warm glue,"detrempe," on paper. One such painting was seento have severe flaking problems. Literaturementions that Vuillard had flaking problems evenwhile he was working. (M.E.)

C. Enamel

Jackson Pollack used enamel for some of his drippaintings on paper. The paper below these enamellines is severly degraded - brown, brittle, andin several cases, cracked. Suspicion that thisearly type of enamel was nitrocellulose. Pollockpreferred it because it dried quickly. (M.E.)

D. Mixed media

1. Acrylic mixed with gouache, e.g. Altoon

2. Foodstuffs combined with traditional media,e.g. Rusche, Rauschenberg


3.4.6. Prints and Printing Inks

A. General considerations about stability andpermanence:

1. Solubility: printing inks are generallyinsoluble in water and most organic solvents.There are, however, exceptions. Inks whichappear safely insoluble in a given solventduring preliminary testing may soften orbegin to bleed during actual treatment,prolonged treatment or reimmersion. Onesoluble component of an ink may be releasedonto the paper or into a bath, or in rarecases the entire ink may soften or solublize.See: 19: Solvent Treatments. 18. Washing.

2. Contemporary and modified formulations: fromthe mid nineteenth century on printing inkformulations become more experimental andbrief spot tests become less reliable inpredicting the stability of these inkstowards immersion in water, alkaline baths,or solvents.

3. Breakdown of binder: "In some black andwhite prints, esp. 19th [c.] prints where theblacks are heavily applied, the oil mediumappears to have disintegrated and the blackpigment lies like chalk on the surface.Obviously these should not be placed in awater bath." (Weidner)

4. Alkaline reactions: Some fear that veryalkaline solutions may saponify the oil inprinting inks, causing the binder to breakdown.

Have seen oil paint stains on the verso of adrawing which had been stable for 100 yearssaponify after deacidification and stainthrough the sheet. (M.C.)

Consideration might be given to introducingthe print first into a neutral water bath andgradually increasing the alkalinity ofsubsequent baths, thus avoiding possibledamage to the oil binder. (L.K.)


5. If a component of a printing ink is softened or solubilized during treatment theconservator can be faced with a split seconddecision:

a. Is it safest to allow the solublecomponent to bleed out into the bath,hopefully resulting in little apparentvisual alteration of the ink andlessening the likelihood that thesolubilized component will be setpermanently, remaining as a disfigurementon the paper support, or

b. is it safer to immediately remove theobject from the bath and treat thebleeding component locally, possibly onthe suction table, or blot and blow dry?

c. When the softening/solubility is overall,clearly immediate removal from the bathis dictated.

6. Storage Problems:

a. Reported softening of lithograph andengraving inks on prints stored forseveral years in fresh cedar shelving.

b. Urea formaldehyde adhesive in plywood mayeffect media. Air circulation importantin storage areas constructed of plywood.

B. Intaglio

1. Engraving (line, stipple, copperplate, steel)

2. Mezzotint: more friable ink surface thanother intaglio techniques. Especiallyfragile as soap was added to enhanceimpression quality.

3. Drypoint

4. Etching (regular, crayon, soft-ground,sugar-lift, relief, aquatint)


C. Planographic

1. Lithograph (crayon, chalk, pen, wash,litho-engraving, litho-etching,litho-mezzotint, chromo-litho)

Red inks on chromolithographs can split andbleed. Deacidification can make the problemworse. Length of time in a bath can becritical (Calder, Toulouse Lautrec, movieposters: 1930s and 1940s).

2. Offset lithograph

D. Relief: (woodcut, metalcut, chiaroscuro woodcut,wood engraving, linoleum print, letter press,zinc etching (relief etching), white engraving onstippled background.

1. 20th century woodcuts: reported pale tintedmaterial bleeding out from inks in early 20thcentury woodcuts in water baths (ProvincetownSchool, Russian Constructivist). The greenink on a Heckel woodcut split and bled yellowto the verso of the print, so caution withGerman Expressionists as well.

2. Some late 19th early 20th c. woodcutsare printed with paste binder ink "a laJaponnaise."

E. Stencil

1. Screenprint (formerly silkscreen)Soft, matte surface is extremely vulnerableto burnishing, even by cover tissue draggedcasually across the face.

Silkscreen prints by Robert Motherwell,framed with plexiglas, developed whitepowdery accretions both on the surface of theprint and on the plexiglas where the two cameinto contact. It is assumed that this was areaction between the plexiglas and thesilkscreen inks.

2. Pochoir Teriade used Linel paints for Matisse's Jazz series: very water soluble and verysusceptible to abrasion. Some colors alsosolvent soluble (e.g. acetone).


F. Hand colored prints

Hand coloring may remain soluble

G. Varnished or glazed prints

"On some prints, in order to heighten a darkcolor, a thin transparent, varnish like coatingis applied to a print, often in a haphazardfashion. This appears to be either a gum resinor gelatin. It is easily water soluble andsometimes becomes crackled, like a varnish on anoil painting and starts flaking off, taking theink and color beneath with it. This has beennoted particularly on Currier and Ives, racingprints and Daumier prints." (Weidner)

The varnish or glaze is often an important partof the history of the print.

H. Japanese woodcuts Colors are derived largely from vegetable sourcesand are highly impermanent.

1. Fugitive: e.g. aigami blue, beni pink, yukonyellow

2. Soluble3. Mica4. Metallic "inks" (brass, tin, silver) often

tarnish.

I. Photomechanical prints

1. Planographic (collotype, Albertype,heliotype, photolithography/photchrome,offset)

2. Relief (wood engraving and zinc relief, swellgelatin or levytype, line cut photoengraving: half tone, fourcolor process,Woodburytype or gravure, photomezzotint,stannotype).

J . Photoelectric (photocopy)(copy art)(transfer photocopy, direct photocopy, colorphotocopy, color and color photocopy)


K. Other

1. Thermography (pseudo embossing): powderedresinous material is blown across the wetprinting ink and fused with heat. This givesit a raised character which imitatesengraving; often in letterheads. Reportedly,the resinous binder in some formulations maysoften and dissolve in solvents (e.g.acetone), leaving behind only the looseraised ink deposit on the surface.

2. Computer art

3. Monotype

4. Collagraph

L. Cautions for printing media during conservationtreatment.



3.5. Bibliography: Media Problems

Arney, Jacobs, and Newman. "The Influence of Oxygen on the Fadingof Organic Colorants, JAIC, 18, No. 2, (Spring 1979),108-117.

Banik, G. and J. Ponahol. "Some Aspects Concerning DegradationPhenomena of Paper Caused by Green Copper ContainingPigments," ICOM Preprints, 1981.

Banik, G. H. Stachelberger and O. Wachter. "Investigation of thedestructive action of copper pigments on paper andconsequences for conservation. Science and Technology in theService of Conservation, IIC Preprints, Wash. D.C. 1982, pp.75-78.

Blythe, Victoria S. "Electrostatic Stablilizing Plate (E.S.P.):An Alternative Method for Stablilizing the Flaking Tendenciesof Works of Art in Pastel," AIC Preprints, Fort Worth, Tx.,1978, pp.21-30.

Brommelle, N. "The Russell and Abney Report on the Action ofLight on Water Colours," Studies in Conservation, 9, No. 4,(Nov. 1964), 140ff.

Brunner, Felix. A Handbook of Graphic Reproduction Processes.Switzerland: Arthur Nigli Ltd, cl962.

Burgess and Charlette, "Aspects of Image Safety in the Use ofEnzymes in Paper Conservation," ICOM Preprints, Ottawa, 1981.

. "The Use of Fixatives to Protect Fugitive ColourantsDuring Conservation Treatments,:" AIC Preprints, Baltimore,Md., May 1983, pp. 129-139.

Cennini, Cennino d'Andrea. The Craftsman's Handbook, translatedby Daniel V. Thompson, Jr. New York: Dover publ., cl960.

Cohn, Marjorie B. Wash and Gouache. A Study of the Development of the Materials of Watercolor. Cambridge, Mass.: Fogg ArtMuseum, cl977.

. "Wash and Gouache: Watercolor at Harvard, AIC Preprints, Boston, Mass, 1977, pp.35-40.

Costicova. "The Regeneration of Colour of the Darkened Lead Whiteby Method of Absorption of Hydrogen Peroxide Vapors," ICOM Preprints, 1978.

Daniels, Vincent. "Colour Changes of Watercolour Pigments DuringDeacidification," Science and Technology in the Service of Conservation, IIC Preprints, Wash. D.C., 1982, 66-70.


Doerner, Max. The Materials of the Artist. N..Y.: Harcourt,Brace and World, Inc., 1962.Ch. 7: "Painting in Watercolors." Ch. 2: "Pigments."

Ellis, M.H. "Charcoal, Chalk and Pastel Drawings: SpecialProblems for Collectors," Part I, Drawing, 1, No. 3. PartII, Drawing, 1, No.4.

. "A Conservation Checklist for Drawings Collectors,"Drawing, I, No. 2, 29-32.

. "Metalpoint Drawings: Special Conservation Problemsfor Collectors," Drawing, 2, No. 3.

. "Watercolors: Special Conservation Problems forCollectors, Drawing, 1, No. 5.

Evans, Debra. "Color Change in Watercolor Pigments," typescriptof talk given at Winterthur, November 1978.Literature survey on the nature and causes of discolorationof specific pigments.

Fairbrass, Sheila. The Problem of Copy Pencil in Works of Art onPaper," The Conservator, UK-IIC, No. 8, 1984.

Feller, R.L. "Studies in the Darkening of Vermillion by Light,"National Gallery of Art Report and Studies in the History of Art, 1967.

Feller, Rbt., Mary Curran and Catherine Bailie. "Identificationof Traditional Organic Colorants Employed in Japanese Printsand Determination of their Rates of Fading," Japanese Woodblock Prints: A Catalogue of the Mary A. Ainsworth Collection. Oberlin, Ohio: Allen Memorial Art Museum,cl984.

Flieder, Francois. "Study of the Conservation of Pastels,"Science and Technology in the Service of Conservation, IICPreprints, Wash. D.C., 1983, pp. 71-74.

Gettens and Stout. Painting Materials: A Short Encyclopedia,New York: Dover Publications, Inc., cl966.

Haner, Paul, Quentin Rankin and Timothy Vitale. "Paintings onPaper: A Dialogue in Five Case Histories," AIC Preprints,San Francisco, 1980, pp. 26-38.

Harding, Eric. "Restoration of Drawings Executed on PreparedPaper," Conservator


Harley, Rosamond D. Artist's Pigments, c. 1600-1835. New York:American Elsevier Publishing Co., 1982.

Hey, M. "The Deacidification and Stabilization of Iron GallInks-Cellulose Combinations on Paper," Unpublished, Wash,D.C.: Library of Congress, 1977.

Johnston-Feller, Ruth, Robert L. Feller, Catherine W. Bailie andMay Curran. "Kinetics of the Fading of Alizarin Lake," AICPreprints, Baltimore Md. 1983, pp.65-73.

Laurie, A.P. The Painters Methods and Materials. N.Y.: DoverPublications, Inc. 1967.Chapters 6-8: "The Pigments used in Painting," theiradvantages and disadvantages.

Maringer, Banik, Stachelberger, Vendl and Ponahol. TheDestruction of Ppaer by Green Copper Pigments, Demonstated bya Sample of Chinese Wallpaper," IIC Preprints, Vienna,18Off.

Matteini and Moles. The Reconversion of Oxidized Lead White inPaintings: A Control After a Five Year Period," ICOMPreprints, 1981,

Mayer, Ralph. The Artist's Handbook of Materials and Techniques,3rd. ed., N.Y.: Viking Press, 1970.

Perkinson, Roy. "On Conservation," Museum News, 53, No. 3,pp.5-7.

Prochazka, M. Palece, M. and Martinek F., "Procedures for MakingTraces of Iron Gallotannate Writing More Perceptible,"Restaurator, 2, Nos. 3-4, (1978),

Stachelberger, Herbert and Gerhard Banik. The IntermicroscopicCorrelation (LM, SEM) of Cross-Sections of WritingMaterials," ICOM Preprints, Copenhagen, Sept. 1984, pp.44-46.

Talbot, Leclerc and Flieder. "Etude de la Regeneration Chimiquedes Encres Metallo-Galliques," ICOM Preprints, Zagreb, 1978.

Thompson, Gary. The Museum Environment. Boston: Butterworths,c.1978. With reference to the effects of generalenvironment, light, pollution, humidity on works of art onpaper.

Watrous, J. The Craft of Old Master Drawings. Madison Wisc.:The Univ. of Wisc. Press, 1957.


Weidner, Marilyn. Conservation of Art on Paper, information sheetfor lecture at Regional Meeting of the American Associationof Museums, Sept. and Oct. 1970. (unpublished)

Welsh, Elizabeth C. "A Consolidation Treatment for Powdery MattePaint," AIC Preprints, San Francisco, 1980, pp. 141-150.

Media Problems outlineCompiled by: Nancy Ash

Contributors: Bob AitchisonVictoria Blythe-HillCraigen Weston BowenMarjorie CohnPia De SantisMargaret EllisKaren GarlickJohn KrillLeslie KruthMeredith MickelsonKitty NicholsonAntoinette OwenJoanne PageLinda SchafferMark Watters

media problems 3. media problems (may 1985) characteristics

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