Physiology or Psychology of Colors

Color has an astounding effect on perceptions & feelings.

Different colors evoke different memories & ideas.

For instance in China the color red

tends to make people feel calm, while

in America red tends to make people

more aggressive. � effect of color on

a persons mind is perceptual, rather

then being physiological & inherent

���� an effect of social training of the

individual

Therefore people dislike unusual

combinations of food, furniture bed

sheets etc with unusual colors.

Examples: green or yellow caviar

or sauerkraut, green or black bed

sheets, green or spotted TV sets ….

The earth tones (browns, oranges, & yellow) Browns cause feeling of

ease & belongingness & safety, and family.

Here is what Joe the Plumber thinks:

Blue & green evoke serenity and peace associated with nature & ocean

White is uninspiring; it is the generic look for many offices. Good color

for warm climates as it reflects light creating cool and breezy feeling

Black is an attention grabber; it also makes rooms look

small and seem restrictive. It darkens a person’s mood

Orange makes people happy, stimulates appetite

Yellow creates a short-term positive effect on the

psychology of people.Long exposure can lead to irritation.

Pink is an extreme calming color: one finds it

impossible to act aggressively against pink creatures �

Red is an exciting color. Red makes Americans aggressive. It speeds up

their metabolism and gives them energy & inspiration

Green is the color of growth, freshness, & welcome

The Subconscious Importance of food Color

Aim is to simulate the color expected by consumer to be

natural such as adding red coloring to glacé cherries

(would otherwise be beige), but also just for effect, like

green ketchup Heinz launched in 2000.

Few people know that seemingly "natural" foods such as

orange & salmon are also dyed to mask natural variations

Why adding dyes to products:

People associate certain colors with certain flavors,

the color of food can influence the perceived flavor

Some of the primary reasons include:

Offsetting color loss due to light, air,

temperature, moisture, storage conditions

Masking natural variations in color.

Enhancing naturally occurring colors.

Providing identity to foods

Protecting flavors from damage by light

Maraschino cherries are

preserved in brine + sulfur dioxide

or alcohol, then soaked in a

suspension of red food dye FD&C

Red 40 +sugar syrup, artificial

almond flavor, while cherries dyed

green by combination of FD&C

Blue 1 & FD&C Yellow 5 are

sometimes peppermint-flavored.

Subconscious effects of Color on Taste

If cherries, & beetroot

were snowy white

instead of red, would

they taste the same to us

Would chocolate taste

different if it were

bright blue?

Do garden peas and

spinach have an

intrinsically green taste?

There is no actual correlation between color and taste, but there is a

perceived one., if something was dirt brown and not chocolate, we'd be

very put off, even if it tasted the same as our favorite fruitcake.

Food presented in an unorthodox manner is dismissed as disgusting

Green caviar, chocolate, meat, blue fish meat

An antigen is a substance that is a close enough fit to bind to the specific

site of an antibody.

Food Colors

An allergen is a substance that binds to specific site of an IgE antibody

Color Additives Permitted For Direct Addition To Human Food (USA)

Certifiable Colors Colors Exempt from Certification

FD&C Blue No.1 (Dye and Lake), Annatto extract, B-Apo-8'-carotenal*,

FD&C Blue No.2 (Dye and Lake), Beta-carotene, Beet powder, FD&C

Green No.3 (Dye and Lake), Canthaxanthin, Caramel color,

FD&C Red No.3 (Dye), Carrot oil,

FD&C Red No.40 (Dye and Lake), Cochineal extract (carmine);

FD&C Yellow No.5 (Dye and Lake), Cottonseed flour, toasted FD&C

Yellow No.6 (Dye and Lake), Ferrous gluconate *, Orange B*,

Citrus Red No.2* Grape color extract*, Grape skin extract*

Paprika, Paprika oleoresin

* restricted to specific juices Riboflavin, Saffron, Titanium dioxide*,

Turmeric, Turmeric oleoresin,

Fruit juice, Vegetable juice

In US, FD&C indicates that FDA has approved colorant for use in

Foods, Drugs and Cosmetics: numbers are given to synthetic food dyes.

In EU, E numbers for all approved additives, both synthetic & natural,

Natural colors are not required to be tested by a number of regulatory

bodies throughout the world, including the United States FDA.

Common Uses of Artificial Food Colors

Common Food Uses

FD&C Blue No.1 dairy products powders, jellies, confections

Brilliant Blue FCF Bright blue Beverages condiments, icings, syrups,

FD&C Blue No.2 Baked goods, cereals, snack foods, ice cream,

IndigotineRoyal Blue confections, cherries

FD&C Green No.3 Beverages, puddings, ice cream, sherbert

Fast Green FCF Sea Green, cherries, confections, baked goods, dairy FD&C

Red No.40 Gelatins, puddings, dairy products,

Allura Red AC Orange-red confections, beverages, condiments

FD&C Red No.3 red Cherries in fruit cocktail and in canned

ErythrosineCherry fruits for salads, confections, baked goods,

dairy products,

FD&C Yellow No.5 Custards, beverages, ice cream

TartrazineLemon Yellow, confections, preserves, cereals

FD&C Yellow No.6 Cereals, baked goods, snack foods, ice cream

Sunset YellowOrange, beverages, dessert powders, confections

Natural food dyesAnnatto E160 cis-bixin + norbixin from red-colored resin coating of the

seeds of tropical bush Bixa orellana) in cheese, oil, butter, smoked fish

Anthocyanins E 163 common red + blue pigment of most flowers, fruits

Betalains E162 red pigment of beetroots, Swiss Chard, pokeweed,

Curcumin E100, yellow pigment of turmeric spice, not water-soluble

Cochineal E120: insect-cactus-derived red pigment from crushing

female Dactilopius coccus insects, expensive rel. to carminic acid

Orcinol E121, red pigment derived from lichen Rocella tinctoria

converted to orcein (red-brown microscopic dye), with ammonia to

orchil – a blue pigment

Carbon black E153 charcoal from plants & animals in liquorice, jam

Capsanthin E160 capsorubin extract from paprika pepper, in eggs, meat

Caramel E150 brown ammonia-treated sucrose in beer, wine, bread, …

Natural food dyesCarotene cis-bixin + norbixin from red-colored resin coating of the

seeds of tropical bush Bixa orellana) in cheese, oil, butter, smoked fish

Lycopene E160 common red + blue pigment of most flowers, fruits

Chlorophyllin E140 in sweets, soups Copper chlorophyllins repl Mg

& are more stable & water soluble olive-green dye

Lutein red pigment derived from lichen Rocella tinctoria converted to

orcein (red-brown microscopic dye), with ammonia to orchil – a blue

pigment

Chlorophyllin E140 in sweets, soups Copper chlorophyllins repl Mg

& are more stable & water soluble olive-green dye

Rhodoxanthin charcoal from plants & animals in liquorice, jam etc

Caramel Caramel is made by heating sugar slowly to around 170 °C (338 °F).

As the sugar approaches this temperature, it melts proceeding to

isomerization & polymerization of the sugars into various high-weight

compounds providing the dark color. Fragmentation reactions result in

volatile low- molecular-weight compounds that create flavor together

with difructose-anhydride. Candies & desserts made with caramel.

Caramel apples or taffy apples

are created by dipping or rolling

apples-on-a-stick in hot caramel,

then rolling them in nuts or other

stuff, and allowing them to cool.

4 cups sugar in sauce pan, add 2 cups water, heat to 170 C water will evaporate, solutin

goes through var stages, watch for brown color, stop because it blackens quickly

Analysis with Natural Pigments

Litmus is water-soluble mixture of different dyes extracted

from lichens, especially Roccella tinctoria, Orchella weeed

or orchil. The mixture has CAS number 1393-92-6. If

absorbed onto filter paper. it becomes a pH indicator.

Cudbearobtained from the lichens

Ochrolechia. Lichen dyes were dissolved in

human urine � gyrophoric acid –yellow dye

Wolfbane lichen (Letharia vulpina), a

fruticose lichen that grows on the bark of pines,

contains a mildly toxic yellow dye called

vulpinic acid.

A brownish dye from the foliose lichen

Parmelia omphalodes is used on hand-woven

Harris tweeds from Scotland..

Dyeing with Natural Pigments

Nothing is more colorful than flowers, insects and birds. However,

early humans must have been frustrated to realize that the dyes

from insects and birds cannot be extracted.

Exceptions confirm the rule:

cochineal, a red dye, + Lac, a scarlet dye is made from ground up

insects.: carmine comes from cochineal (natural red 4) lac (natural red

25) and hematein which comes from the logwood tree (natural black 1).

Tyrian purple was an expensive dye in antiquity extracted from the

aquatic mollusk Murex brandaris. imperial purple is a purple-red dye

which was first produced by the ancient Phoenicians in the city of Tyre.

Plant Colors & Humans

The painters of the walls of Lascaux & Altamira

used mineral pigments, the Celts of Britannia did

not blue themselves with woad (as ascerted by

Caesar) but with Copper minerals

Experimenting with plants, that the beautiful colors of

flowers are ephemeral. They do not adhere to body or

cloth, wash out easily & fade in the sun. (exception is

anatto serving the Secoya Indians well). Early humans

used minerals for cave paintings & body ornaments.

To make plant dyes last meant mastering the chemistry of

dye binding & fixation to the fabrics such as wool &

cotton. Mordants like fermented urine, vegetarian ashes,

and minerals like aluminum & potassium sulfate ( =

alum) were used.

Egyptians stained their flax fibers blue with extract from

Acacia, red with Safflower, & yellow with madder.

Dyeing with Plant Dyes

Many dye plants need no mordants since they

contain lots of tannins on their own.

Lichens, Black Walnut fruit hulls, Oak

acorns, alder catkins, sumac berries etc.

No mordants needed

Dyes like tumeric, beets , blueberries, apple

peels, cherries etc. need mordants to become

permanent 7 stand up to fade & wash testing.

Mordants are substances that bind or fix the

dye permanently to the fibers.

Most common mordants are (1) ALUM= Al, K, NH3 sulfates normally used 1,5 g / l

& CREAM of TARTAR (= tartaric acid, i.e.

wine acid, normally used at 2.5 g / l

Plant Colors & Humans

Indigo. Leaves were harvested & mashed

in water. Beating the slurry aerated the mix

& precipitated the dye, then dried & shiped

Classical Europe imported most plant stains from Asia.

Wood dyes. The dark heartwood of the

Indian Sander or Sandalwood tree Pterocarpus

santalinus (Fabaceae) produced the brilliant water-

soluble red of Indian textiles. An alternative source

were the pods of the Sapper tree, also an Indian

legume. Much later in History replaced by

American trees like Brazilwood & Quebracho.

Cochineal. It is a red dye obtained from scale

insects living Kermes oaks e.g in Armenia.

Insects were harvested in the fall, pressed into a

material called kermes & shipped to the west.

Flower Pigments

Dyers’ Chamomile (Anthemis tinctoria)

Beautiful daisy flowers which yield a strong

yellow dye, the flower heads are harvested and

used when freshly picked or dried for winter

storage.

Safflower flower heads are dried & used for

colouring foods & clothing, and making red

(carthamin) & yellow dyes (carhamidin – a

flavonoid),

The roots of the madder plant Rubia tinctorum

supply the coloring substances that are converted

to madder lakes, the principle coloring substance

which is alizarin. The shades of colors vary from

scarlet (stannous madder lakes), carmine red (to

red with a bluish tint (alizarin lakes).

Flower Pigments

Tanacetum vulgare, Tansy, Roundish, button-like, yellow flower

heads in terminal clusters from mid-to-late summer. Traditional

dyers use both tansy leaves & flower buttons to produce a golden-

yellow color (flavonoids). For 100 grams wool you need 300

grams tansy. The plant can also be dried. Before dyeing simmer

wool for 1 h at 90 C in alum solution. 20 g alum for 100 g yarn.

Other common names include Weld (Reseda

luteola), Dyer's Rocket, dyer’s broom, is a

European plant with long spikes of small, yellowish-

green flowers cultivated as a source of yellow dye

Calendula officinalis, Pot Marigold, Asteraceae. native to southern

Europe. The petals and pollen of Calendula officinalis contain the

carotenoids flavoxanthin and auroxanthin as antioxidants, & source

of their yellow-orange coloration. The carotenes promote the

renewal of skin tissue + antibacterial properties prevent infections.

As a rinse for the hair, pot marigold gives a golden tinge to fair

hair: Viking women used it to dye their hair & textiles yellow.

Flowers to Color � Marigold petals do not fade

Marigold (Calendula officinalis) in Asteraceae,

native to Iran. not to be confused with other

marigolds, such as Tagetes, corn or marsh marigolds.

Petals used to add color to salads (carotenes, 80 %

lutein + flavins), extract is common food additive to

produce darker egg yolks. Aroma not sweet,

resembles hops in beer. The oil from its seed contains

calendic acid.

Perfume oil of patchouli

Once used as blond hair dye, still wholesome

coloring agent in for cheese, soups & salads +

textiles: for 110 g cotton/wool: Needs previous

1 h cooking in mordant: 30 g alum + 10 g

tartaric acid in 300 ml water. Transfer to

simmering solution of 250 g flowering heads,

cover with water & boil until right color is

achieved.

Used by Gipsy women to keep

their hair black.

Herb yields dark pigment

Gypsies were reputed to stain their

skin with the juice of the plant,

althgough Howard (1987) states

that they used it to dye their linen

Gipsywort Lycopus europaeus

Extract red- to-

dark brown

pigment with

hot water.

Nature of

pigment

unknown!

plant melanin??

Henna (Lawsonia inermis, is a flowering plant

form North Africa. it does not thrive where

minimum temperatures are below 11 °C. used

since antiquity to dye skin, hair, fingernails, leather

and wool. Lawson is a Quinone that stains proteins.

Henna Lycopus europaeus

For skin dyeing, a paste of ground henna

(either prepared from a dried powder or

from fresh ground leaves with lemon juice

or vinegar) is placed in contact with the

skin from a few hours to overnight. Henna

stains can last a few days to a month

depending on the quality of the paste,

individual skin type, and how long the

paste is allowed to stay on the skin. Henna

also acts as an anti-fungal and a preservative , it

is a UV protectant.

lawsone

Lawsone (2-hydroxy-1,4-

naphthoquinone), also known as

hennotannic acid is a water-soluble

red-orange dye

From the leaves of the henna plant

(Lawsonia inermis) as well as

jewelweed (Impatiens balsamina).

Henna Lycopus europaeus or jewelweed (Impatiens balsamina).

lawsone

jewelweed

Slightly acidic henna extracts contain

lawsone, which reacts chemically with

the protein keratin in skin and hair,

Lawsone strongly absorbs UV light, and

aqueous extracts can be effective sunless

tanning sunscreens. Chemically, lawsone

is similar to juglone, which is found in

walnuts..Walnut Juglans

Indigo as in blue jeans (Strauss 1873)

Is challenging dye to use because it is

not soluble in water; to be dissolved,

water must be free of oxygen.

In temperate climates

indigo is obtained from

woad (Isatis tinctoria) and dyer's

knotweed (Polygonum tinctorum).

BASF developed a commercially

feasible manufacturing process in

1897, by 1913 natural indigo had

been almost entirely replaced

How to stain clothing with Indigo Indigofera tinctoria)

India was supplier to Europe as

early as Roman era. Association of

India with indigo is reflected in

Latin word indicum, for the dye

Extraction of indigotin from leaves:

extraction in O2-free alkali turns

water blue in 24 h. Aeration

(paddling) precipitates indigotin.

Blue sludge is dried and sold.

Requires no mordant, but alkaline

(add 1 TBS alkali NaOH to 1 l water

pH 10-11 + 1 oz of indigo powder) &

O2-free bath (add 1 TBS thiourea

dioxide or Na hydrosulfite). Wait 15

min to reduce & mix � solution

turns from transparent green-yellow

to blue showing oxidized form. Test

by dripping some solution on paper.

Cotton requires pH 11.

Woad biennial in family Brassicaceae

Woad also name of the blue dye. The

blue pigment indican is the same as in

indigo, it is insoluble in water, alcohol,

but soluble in chloroform, H2 SO4

woad might prevent cancer, having

more than 20 times more glucobrassicin

than broccoli. Young leaves when

damaged can produce even more

glucobrassicin, up to 65 times as much

leaves crushed with wooden rollers,kneaded into 3-inch-diameter balls.

This gave the workers black hands. balls were dried and ground into

powder piled into deep layers. layers were watered to ferment

(breakdown of indican, a glycoside - to dyestuff indigotine) producing

horribly foul odors from sulfur-containing glucobrassicins . After two

weeks of fermentation, the leaves dried; powder contained indigotine

Woad (Isatis tinctoria )

Red Indian Dyes

Navahos made the famous Navaho rugs for US tourists from wool

(sheep introduced by Spain), very selective colors have symbolic

meaning: Red = sun and life, Indians themselves “the people”,

Yellow, orange = sunset or the ending, White = dawn or the

beginning, Black = rain and joy (Seattle?)

Alnus sp. Alder, bark stained deerskin red-brown

Coreopsis. Blossoms dye wool dark red

Opuntia prickly pear: fruits boiled with salt spruce bark

Rhus sumac berries used to dye baskets & body

Sanguinaria Bloodroot pounded rhizomes gave face paint

Rust or Iron ores, red to brown for totem poles and body

Animal blood mixed with fat used to color totem poles

Indigofera leptosepala Native indigo ferment. in urine

Chrysothamnus sp. Rabbit brush bark boiled to produce

green color, the flowers boiled for 6 hours for deep yellow

Xanthorhiza yellowroot for baskets

Hydrastis canadensis goldenseal roots for baskets

Xanthorhiza yellow root ���� berberine

The Yellowroot (Xanthorhiza simplicissima, syn. X.

apiifolia) is one of the few plants in the family

Ranunculaceae with a woody stem (the other notable

example being Clematis), native to the eastern

United States. It was used to produce a yellow dye

by Native Americans. The species name refers to the

simple (not branched) root.

While yellowroot is toxic in large doses, it has

been used as a substitute for Hydrastis

canadensis. Native Americans also used it to treat

various skin ailments. According to Foster &

Duke (1998), the plant contains berberine which

is anti-inflammatory and can produce a transient

drop in blood pressure.

Xanthorhiza yellowroot and also Hydrastis

canadensis goldenseal roots were used to dye

baskets

Alizarin is an anthraquinone

originally derived from roots of

the madder plant. Tut’s cloth had

it. 1869 first pigment to be

duplicated synthetically. Related

dyes: Alizarine Cyanine Green G

Alizarine Brilliant Blue R

Madder is the common name of

Rubia, a genus of 60 species of

perennial climbing native to Old

+ New world: Common Madder

(Rubia tinctorum), Wild Madder

(Rubia peregrina), and Indian

Madder (Rubia cordifolia).

Madder (Rubia tinctorum) � alizarin red

From the Arabic Alkanna ( a

term for henna).

The root has a red unidentified

pigment. The leaves have highly

poisonous alkaloids

Alkanet - Pentaglossum sempervirens

Anthraquinone resorcinol-type pigment is easily extracted from Alkanet

root by oil & ethanol. It imparts a ruby red color to natural fibers,

wool, wood, stone, lip balm, lipstick, ointments, salve, soap, lotion, and

to tint oils, vinegar, tinctures, varnishes, or wine. In the past, it was used

to improve the appearance of low quality wines and ports, and to give an

aged appearance to wine corks. In soap, it will yield shades of pink,

blue, and purple, depending upon the amount used, types of oil used,

and the alkalinity of the soap.

Saffron, has for decades been the

world's most expensive

spice,derived from the 3 dried

stigmas of the flower of the

saffron crocus (Crocus sativus).

Stigmas are dried & used in

cooking as a seasoning and

coloring agent.

Saffron - Crocus sativus

Saffron has a bitter taste & hay-

like fragrance; It also contains a

carotenoid dye, crocin, that gives

food a rich golden-yellow hue.

Saffron also has medicinal

applications.

Crocin – a carotenoidal glycoside

Woad biennial in family Brassicaceae

Woad also name of the blue dye. The

blue pigment indican is the same as in

indigo, it is insoluble in water, alcohol,

but soluble in chloroform, H2 SO4

woad might prevent cancer, having

more than 20 times more glucobrassicin

than broccoli. Young leaves when

damaged can produce even more

glucobrassicin, up to 65 times as much

leaves crushed with wooden rollers,kneaded into 3-inch-diameter balls.

This gave the workers black hands. balls were dried and ground into

powder piled into deep layers. layers were watered to ferment

(breakdown of indican, a glycoside - to dyestuff indigotine) producing

horribly foul odors from sulfur-containing glucobrassicins . After two

weeks of fermentation, the leaves dried; powder contained indigotine

Woad (Isatis tinctoria )

Genista tinctoria, with common

names: Dyer's Broom, Dyer’s

Greenweed. I t was from this plant

that the isoflavone genistin and its

aglucone, genistein,was first

isolated in 1899; and hence the

name of the chemical compound.

The medicinal parts are the

flowering twigs. The tincture or

extract can be used externally for

herpes or tetters.

Dyer’s Rocket Genista tinctoria

Pigment is a Flavonoid: 2 % of the dry

weight Plant material extracted with

hot water, add wool or silk to to extract

and simmer at max. 80°C

Other species with flavonoids

is Weld (Reseda luteola), The

yellow dye was obtained from

the roots of R. luteola by the

first millennium or 900 BC

Mignonette (Reseda) is a genus of

fragrant herbaceous plants native

to the Mediterranean region The

species include annuals, biennials

and perennials, and grow to 40-

130 cm tall. Flowers are produced

in a slender spike, each flower

small (4-6 mm diameter), white,

yellow, orange, or green, with four

to six petals. The volatile oil is

used in perfumery.

Weld: Reseda luteola + R. odorata

Pigment is a Flavonoid: 2 % of the dry

weight

Plant material extracted with hot water,

add wool or silk to to extract and

simmer at max. 80°C

Other species is Weld (R.

luteola), Dyer's Rocket

The yellow dye was obtained

from the roots of R. luteola by

the first millennium or 900 BC

Lincoln green is the color of dyed

woolen cloth associated with Robin

Hood and his merry men in Sherwood

Forest, Nottinghamshire The dyers of

Lincoln, a cloth town in the high

Middle Ages, produced the cloth by

dyeing it with woad (Isatis tinctoria)to

give it a strong blue, then overdyeing it

yellow with weld (Reseda luteola) or

dyers' broom, Genista tinctoria.

Robin Hood – the green of forest bandits

Pigment is a Flavonoid: 2 % of the dry

weight

Plant material extracted with hot water,

add wool or silk to to extract and

simmer at max. 80°C

Other species is Weld (R.

luteola), Dyer's Rocket

The yellow dye was obtained

from the roots of R. luteola by

the first millennium or 900 BC

Native to SE Europe,

contains 5-10 % tannic acid

(= natural mordant)

�subtle dye from elephant grey

to parchment (beige).

�Chestnut tannin is one of the

pyrogallol class of tannins.

�Since it tends to give a reddish

tone to the leather, it is often

used in combination with

quebracho.

Chestnut - Castanea sativa Horse chestnut Aesculus hippoc.

Aesculus hippocastanum is a large

deciduous tree, commonly known

as Horse-chestnut. Native to small

area in mountains of the Balkans.

Aesculin is fluorescent whitener

saponin aescin, used for health

(varicose veins, edema)

Used are the hulls = exocarp or

outer coverings of the fruit

Walnut hulls are substantive or

direct dyes = no mordant required

contains > 10 % tannic acid and

quinone pigment juglone

� Rich brown color of juglone

do not raise temps above 180 F and

10 % walnut extract

Black Walnut Juglans nigra

Walnut hulls gave the famous

grey color for the cotton uniforms

of the Confederate Army during

Civil War

Cutch tree is native to India is

used for many purposes breath

freshener & diuretic

The wood is chipped and boiled,

the sap dissolves & liquid becomes

syrupy. Liquid is cooled, pressed,

cut into pieces & ground into

powder

When dyeing with cutch extract

the dye becomes not only deeper

but redder the more it is simmered.

Other wood dyes:

Logwood Heamatoxylon, red alder

Alnus rubra, red sandalwood,

fustic Chlorophora etc.

cutch – Acacia catechu – a wood dye

Dye for all fibers :

with alum� yellow-to-red brown

with iron sulfate � black-brown

with soda ash=Na carbonate � red

Carminic acid & Scleranthus perennis

Carminic acid is a red glucosidal

anthraquinone structure that occurs

naturally in some scale insects such as

the Mexican or Polish cochineal.

insects prod. acid as feeding deterrent.

Carminic acid is pigment in carmine.

= C.I. 75470 and C.I. Natural Red 4.

Perennial knawel (Scleranthus

perennis ) is a perennial herb of the

carnation family. It grows on sandy,

dry, acidic soils of Central Europe.

Polish carmine

scales are used to

produce a crimson

dye colloquially

known as Saint

John's blood.

larvae of P.

polonica live on

the roots of various

herbs – esp. knawel

(from Knauelkraut

German)

Logwood tree (Haematoxylum

campechianum grows in Central America &

led to founding of Belize from British

logging camps of 17th century. an important

histological stain. (H. + Eosin = popular for

animal cells

Haematoxylin, hematoxylin, Natural Black 1, or

C.I. 75290 extracted from the wood of the tree.

oxidised it forms haematein = blue-purple color,

used, together with a suitable mordant (Fe(III) or

Al(III) salts), to stain cell nuclei. Structures that stain

with haematoxylin are called basophilic.

Related to Brazilin - red

pigment from brazilwood

Caesalpinia. Natural red 24

= dye for fabric, paints, inks

in acidic sol yellow, alk red

Logwood tree (Haematoxylum campechianum)