The art of Dyeing - No.5. Red on Silk. Cochineal Red. London Scarlet.

Scientific American 20, 27.1.1855

Red on Silk

Silk is generally dyed in the yarn state, as none but that of the softest quality, in the piece, can be colored without creasing and injuring the appearance of the fabric, excepting by the use of complicated machinery. As has been stated in former articles, almost all silk has to be deprived of a naturul gum previous to being colored. — Some silk is dyed in a gummy state, but the amount is small, and of this we will not speak. Silk, cotton, and wool, to be dyed any of the primitive colors — yellow, red, and blue — must be white, or they cannot be dye a pure color. Only two kinds of substances are commonly employed for coloring red on silk, namely, cochineal and red wood — embracing Brasil, peachwood, or Nicaragua. The mordant for Brazil wood red is simply alum, a tub of which is kept standing at a strength of about 3° hydrometer, or of a strong taste. As it Is a simple color to dye, the peculiar strength of the mordant need not trouble any person who wishes to dye this color. The silk being deprived of its gum and soap, and well washed, is wrung (if in yarn,) and entered into the above tub, where it is handled for about ten minutes and sunk beneath the liquor, and allowed to steep thr about four hours. It is thru lifted and dripped, and washed in one tubfull of clean cold water, and is wring and scutched on pins for the dye stuff. About four pounds of good Brazil wood boiled will dye ten pounds of silk yarn. This should be given hot in a tub, and the silk entered and handled for about half an hour, wnen it will be found to have acquired a good full color. It then washed well in cold water, wrung, and dried. Some dyers give their dye stuff at two separate times, one-half in the first tub and one-half in a second tub, and this is the best plan. The alum should always be given cold, and the dye stuffs should be given moderately cold in the first tub, and pretty hot in the second. Peach wood and Brazil wood should be kept boiled up in strong liquor for dyeing either silk or wool.

Old silk dresses, if boiled in a strong solution of soap, then well washed, and the old color discharged in a hot liquor of diluted sulphuric acid, and well washed again, can be dyed a good red by the same mode as that described for white silk yarn. Ribbons may be dyed in this manner by any female by simply making up a solution of alum in a crock, and proceeding as above directed for the silk dress. Old ribbons can in this manner, if they are of soft silk, be made to look equal to new. They can be stiffened with a little weak white glue, dissolved in water, and ironed on the wrong side with hot iron. All Brazil wood reds are of a rich color, but inclined to a ruby shade, that is, they are not of a bright red color. Another way to dye red on silk with Brazil wood, is by making up a strong standing tub of the nitro muriate of tin and Brazil wood liquor, and handling the silk in this till it is the proper depth of color. This liquor must be very strong, the spirits at the ratio of 3°, and the dye wood liquor as strong. For common purposes, this method of dyeing red on silk should not be pursued. If a very few drops of the nitro muriate of tin is added to the last liquor — for dyeing by the alum process, as described — a few minutes before the silk is finished (but it must be lifted out of the tub for this purpose,) it will make the color more brilliant.

Cochineal Red

This is the most beautiful red that is dyed on silk, and far exceeds all ancient colors for brilliancy. The mordant for this is nitro muriate of tin spirits, and cream of tartar. The spirits should be strong, about 3° in the hydrometer, and for each pound of silk no less than three ounces of cream of tartar should be mixed with the spirits. The silk is spirited moderately hot, handled for half an hour, and left to steep for three hours. It is then lifted, squeezed, or wrung, and is ready to receive the cochuneal. It takes no less than four ouuces of cochineal to dye one pound of silk. This is ground fine, put into a clean copper kettle and boiled for ten minutes. It is then put off the boil and cooled a little down, and the silk entered end handled at a scalding heat, for three quarters of an hour, when it will be found to be a beautiful color. To dye white crape shawls a full red, it requires six ounces of cochineal to every pound weight of the shawl. Four ounces of good cochineal will dye fifteen yards of silk. By preparing silks with alum instead of spirits, they can also be dyed red with cochineal, but they must lie in the alum for at least six hours.

London Scarlet.

The London jobbing dyers, in dyeing crape shawls a scarlet color, give them first a strong body of annatto, then steep them over night in a tub of strong cold alum liquor, and give the cochineal as has been described, in a kettle at a scalding heat, with two ounces of spirits for every heavy crape shawl. They allow four ounces of cochineal for every pound weight of silk, but the experience of New York jobbing dyers is different; they have to give six ounces of the common cochineal. All silks should be well washed before they are dried. There is no fear of spoiling this color with too much cochineal; it is too dear to be used indiscriminately.

Crimson is a binary color, composed of the red and blue rays, but it is commonly called red, because the red ray greatly predominates. It is dyed by preparing silk with a strong body of archil, instead of the annatto as for scarlet, and then dyed a cochineal red on the top of this, by putting the silk through the whole process described. After being dyed red it can be toned down to any depth of crimson by handling in a weak alkaline liquor; urine is used for this purpose. Silk in pieces about twenty yards in length, can be handled easily by selvedging.

London has been long distinguished, in England, for dyeing the finest cochineal reds, and the spirits; which are made there for this purpose used to be sold to all the other dyers throughout that country. The simple muriate of tin, however, makes a very good spirits, but the red they produce is more on the blue shade than spirits made having the greatest proportion of nitric acid. All nitro muriate of tin spirits, for cochineal red colors, should have one ounce of sal ammoniac added in a dissolved state, to every gallon of spirits. This removes any trace of iron
(which saddens the color) that may be in the nitric acid, and there is but little made which is free from it. The next article will relate to dyeing blue.

Note — James Yates, in writing to us from Bridgeport, Ohio, thinks these articles in the Scientific American imperfect for country manufacturers, "because," as he says, "they do not tell us how to make or proportion the different acids, and how much tin to put in." He is mistaken so far as it relates to the making of spirits, if he means this. On page 130, we gave the proportions of acid and tin; the proportion of tin is to feed it slowly in, till the acid will take no more. The complicity of spirits, and the mystery which some dyers throw around them, is all fudge. If Mr. Yates wishes to know how to make acids, we can inform him, but it is no more a part of the dyers regular bueiness than to make indigo, the bichromate of potash, or to cultivate tho cochineal insect. Mr. Yates will never go wrong, if he is a country dyer, and uses no other spirits than the simple muriate of tin — fully saturated with pure tin.

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