The London Encyclopædia: Part II. The Practise of Dyeing. Of Dyeing Brown.
The London Encyclopædia, or Universal Dictionary of Science, Art, Literature, And Practical Mechanics, Comprising A Popular View of The Present State of Knowledge.
By The Original Editor of The Encyclopædia Metropolitana, Assisted By Eminent Professional And Other Gentlemen.
In Twenty-Two Volumes
Printed For Thomas Tegg, 73, Cheapside;
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Part II. The Practise of Dyeing. Of Dyeing Brown.
227. The substances employed in [creating?] browns are very numerous, but those chiefly used are sumach, walnut-peels, and walnut-[wood?].
On separating the bark from the [... sub?]stance of the walnut-root, says Berthollet [...] some experiments on the subject the [...]
yielded in equal weight a liquor much more charged with color. The bark of the wood of walnut also exhibited properties approaching to those of walnut-peels, but its decoction formed a blackish precipitate with sulphate of iron.
Walnut-peels exercise a lively action on oxide of iron, dissolving it, and forming a liquor as black as ink. If boiled along with clean filings they fo not attack them; but, if left exposed to the air, the liquor becomes soon black.
The coloring matter of walnut-peels has a great disposition to combine with wool. It gives it a very durable walnut or dun color, and mordants appear to add little to its permanence, but they may vary its shades, and give them more lustre. By preparing the stuff with alum, a richer and [...] color may be obtained.
Walnut-peels are of excellent use, because they give agreeable and very durable shades, and, being employed without any mordant, they preserve the softness of the wool, and require but [...] simple, and not expensive, operation. Walnut-peels are gathered when the nuts are entirely ripe. Large casks or tubs are filled with tem, and a sufficiency of water is poured on them to cover their surface. In this state they may be kept a year and upwards. At the Gobelins, where a very extensive and varied use is made of this ingredient, it is kept for two years before it is employed. It is found then to furnish much more color. It has a very unpleasant putrid odor.
The peels may also be used which are taken from the nuts before they are ripe; but they fo not keep so long.
228. The following are the results of M. Berthollet's experiments on sumach (rhus coriaria): - The infusion of sumach is of a dun color, bordering on green. It speedily becomes green in the air. When it is recent, the solution of potassa produces little change on it. The acids clear up its color, and render it yellow. Solution of alum makes it turbid, producing a scanty yellow precipitate, while the liquor remains yellow.
Acetate of lead forms instantly an abundant yellowish precipitate, which takes a brown color on its surface; the liquor remains of a clear yellow.
Sulphate of copper affords a copious yellowish-green precipitate, which, after some hours, changes to a brown-green. The liquor remained clear, and a little yellow.
Sulphate of zinc of commerce rendered the liquor turbid, blackening it, and forming a deep blue precipitate.
Pure sulphate of zinc deepened the color much less; only a slight dun deposite, verging on brown, took.
Muriate of soda produced no sensible change at first; but after some hours, the liquor was a little turbid, and its color had become somewhat clearer.
Sumach acts like nut-galls on solution of silver, whose metal it reduces; a result promoted by the action of light. We have already dwelt at sufficient lenght on the explanation of this phenomenon, as well as the general properties of astringents. Sumach affords of itself a fawn-color bordering on green; but it communicates to cotton stuffs several very permanent colors, when they are combined with mordants.
229. Sanders, or sandal-wood, is also employed for the purpose of giving a fawn-color. There are three kinds of this wood, the white, the yellow, and the red. The last only, which is a compact heavy wood, brought from the Coromandel coast, is used in dyeing. By exposure to the air it becomes of a brown color: when employed in dyeing, it is reduced to fine powder, and it yields a fawn-color with a brownish shade, inclining to red.
The quantity of coloring matter, however, which it yields of itself is small, and it is said that it gives harshness to woollen stuffs. When it is mixed with otrher substances, as sumach, walnut-peels, or galls, the quantity of coloring matter is increased; it gives a more durable color, and produces considerable modifications in the coloring matter with which it is mixed. Sandal-wood yields its coloring matter to brandy, or diluted alcohol, more readily than to water.
230. Soot communicates to woollen stuffs a fawn or brown color, of a lighter or deeper shade, in proportion to the quantity employed; but the color is fading, and its affinity for wool is not great; and, besides leaving a disagreeable smell, it renders the fibres harsh. In some manufactories, it is employed for browning certain colors, and it produces shades which could not otherwise be readily obtained.
231. In dyeing with walnut-peels, a quantity proportioned to the quantity of stuff, and the intensity of shade wanted, is boiled for fifteen minutes in a copper. All that is necessary in dyeing with this substance is, to moisten the cloth or yarn with warm water, previously to their immersion in the copper, in which they are to be carefully stirred till they have acquired the proper shade. This is the process, if the aluminous mordant be not employed. In dyeing cloth, it is usual to give the deepest shades first, and the lighter ones afterwards; but, in dyeing woollen yarn, the light shades are given first, and the deeper ones afterwards. A fresh quantity of peels is added each time.
232. Berthollet made a number of experiments to ascertain the difference of color obtained from the simple decoction of walnut-peels, and the addition of metallic oxides as mordants. The oxide of tin, he informs us, yielded a clearer and brighter fawn-color than that of the simple decoction. The oxide of zinc produces a still clearer color, inclining to ash or gray. The color from oxide of lead had an orange cast, while that from oxide of iron was of a greenish brown.
233. A fawn-color, which has a shade of green, is obtained from sumach alone; but to cotton stuffs, which have been impregnated with printers' mordant, or acetate of alumina, sumach communicates a good and durable yellow.
234. Vogler employed the tincture of sanderswood for dyeing patterns of wool, silk, cotton, and linen, having previously impregnated them with a solution of tin, and afterwards washing and drying them. Sometimes he used the solution unmixed, and at other times added six or ten parts of water, and in whatever way he em-
ployed it, he obtained a poppy color. When the mordant employed was olution of alum, the color was rich scarlet; with sulphate of copper it was a clear crimson, and with sulphate of iron beautiful deep violet.