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The Secret of Everyday Things by  Jean Henri Fabre


 

 

DYESTUFFS

[71]

"C
OULDN'T you tell us, Uncle Paul," said Marie, "how all those colors we see on printed goods are obtained? There are such beautiful reds, blues, violets, that real flowers can hardly compare with them."

"Yes, I will tell you. Let us first take madder, the most valuable of dyestuffs on account of the beauty and fastness of its colors. It is the root of a plant cultivated in France, chiefly in the department of Vaucluse, and of about the size of a large feather, reddish yellow in color. The preparation it undergoes before being used in dyeing consists simply in reducing it to very fine powder and purifying it as much as possible.

"Madder by itself imparts absolutely no color to [72] any stuff, be it silk, wool, cotton, or whatever other you please. One might boil for days at a time a piece of percale in water containing powdered madder; the fabric would remain white. For the color to take form and impress itself on the stuff there is some essential condition lacking."


[Illustration]

MADDER

"No doubt it needs what you call the mordant, that substance that mixes with the dye to bring out the color and fix it on the goods, just as gallnuts bring out the black of ink by mixing with copperas."

"That is it: it lacks the mordant. In the case of madder this is sometimes iron-rust and sometimes a white substance resembling starch and called alumina, which is obtained from very pure clays. If the material to be dyed is first saturated with a strong solution of alumina, it takes a dark red tint on being dipped into boiling water containing a proper amount of powdered madder. If the quantity of alumina is small, the resulting tint is simply rose-color. Thus by varying the proportion of the mordant any shade can be given to the fabric, from the deepest red to the palest pink.

"With iron-rust for mordant other colors quite unlike the preceding are developed. A liberal quantity of rust gives black, a small quantity violet—always with madder, be it understood. Finally, if the mordant is a mixture of alumina and rust the color produced is a chestnut brown, intermediate between red and black, and varying in shade according to the proportions of the ingredients used. You see, then—and it cannot fail to surprise youÔthat with a single dyestuff, madder, it is easy to obtain a numer- [73] ous series of tints ranging from dark red to pale pink, from deep black to delicate violet, and including also the chestnuts or mixtures of red and black.

"Let us suppose the calico-printer has stamped the different mordants on the goods with his printing-block and has artistically grouped them to obtain bouquets of flowers. This done, the cloth appears merely soiled with unsightly blotches, the iron-rust showing with its dirty yellow, while the alumina, being colorless, remains invisible. But as soon as the piece is plunged into a boiling bath of madder each mordant attracts to itself the coloring matter dissolved in the water, incorporates it, and with it forms such and such a color according to its nature. The reds, pinks, blacks, violets, chestnuts, all come out at the same time before our astonished eyes, which at first might imagine themselves beholding the birth of enchanted bouquets."

"If you had not explained this curious operation," said Claire, "I should have been astonished to see those magnificent printed bouquets taking shape all by themselves in the confusion of that boiling vat."

"Then it is in that one vat," added Jules, "containing only water and madder, that there are formed all at the same time the reds, pinks, and violets for the flowers, the chestnuts for the bark of the branches, and the blacks for the shadows. The bouquets lack only the green of the leaves to be complete."

"Madder does not give green; another substance and another operation are necessary to obtain that color. Nevertheless, who could fail to perceive the [74] importance of madder, that one substance which furnishes so many hues, so remarkable not merely for their beauty but also for their unequaled permanence? No other dyestuff contains in itself so many excellent qualities."

"And the other colors—blue, for example—how are they obtained?" asked Marie.

"The most lasting blue is the product of a plant called the indigo-plant. It is too cold in our part of the world to raise this plant, but it grows on the warm, damp plains of India. It is the leaves that are used. They are green at first, but if they are allowed to go to decay in water containing a little lime, a substance having a superb blue color and called indigo is formed from them.

"A very beautiful yellow remarkable for its fastness is prepared from a plant that grows around here and is known as woadwaxen or dyers' greenweed, bearing flowers closely resembling those of the mignonette, so famous for its sweet odor. By mixing this yellow with blue we obtain the green that Jules spoke of as needed for the leaves of the bouquets.


[Illustration]

WOADWAXEN DYERS' GREENWEED

"A small, rather ugly-shaped insect gives the dyer his most beautiful reds. It is known as the cochineal, and it lives all its life in one spot, as do the lice [75] of our rose bushes. It infests a fleshy plant whose branches are flattened in the shape of a palette and studded with tufts of thorns. This plant is known under the names of nopal, cactus, Indian fig, and Barbary fig. Mexico produces most of the cochineal. The insect is gathered from the nopal, killed by immersion in boiling water, and dried in the sun. It then looks like a little wrinkled seed. About one hundred forty thousand insects are required to make one kilogram in weight. It is only necessary to boil the cochineal in water to obtain a red liquid which deposits as sediment the beautiful coloring matter known by the name of carmine. Wool and silk are dyed scarlet with cochineal.


[Illustration]

FEMALE COCHINEAL

"I will conclude with a few words on the brightest, clearest of all dyestuffs, but unfortunately, also, the most changeable, the most evanescent. Recall the splendid hues now given to wool, silk, and above all to ribbons. The rainbow alone can rival them. Now do you know the origin of these colors, so pure, so bright, so charming to the eye? They come from a horrid, malodorous substance called coal-tar.

"In the first place you should know that illuminating gas is obtained by heating coal red-hot, in large iron vessels to which no air is admitted. The heat liberates at the same time gas for lighting and tar which is set aside by itslef; there is then left a kind of coal, light, shiny, full of holes, and called coke. Let us turn our attention to the tar only, which [76] despite its disgusting appearance is one of the most marvelous products known to the manufacturing world. By treating it first in one way, then in another, and after that in still another, there are obtained from it a number of very different substances, some resplendent like mother-of-pearl or the scales of fishes, others white and powdery like fine flour, and still others resembling limpid oil and having in certain instances a strong and disagreeable odor and in others an aromatic fragrance. When this separation is complete, we have at our disposal various substances which further processes will transform into colors of all kinds. One of these substances derived from coal-tar, and at first a colorless oil, becomes an azure blue that would not disfigure the wing of the most gorgeous butterfly; another, at first a floury powder, reproduces exactly the colors yielded by madder; a third gives shades of red beside which the queen of flowers, the rose, would look pale. But one capital fault is common to most of these splendid colors obtained by man's skill from the somber coal: hardly any of them can stand the least washing without injury, and even light alone fades them quickly.

"Colors that are really fast, those that last as long as the fabric that bears them, and can without fading stand light and soap, are particularly the colors obtained from madder, the browns and blacks into the making of which gallnuts have entered, the blues from indigo, and the yellows of woadwaxen. Beware of a dye that charms the eye but turns dim under the first ray of sunlight or with the first washing."


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