The Art of Dyeing. - No. 30.

Scientific American 45, 21.7.1855

Fast Black on Woolen Goods - If woolen goods are first dyed a light reddish color with camwood, and then finished in a blue vat, the most durable color known is obtained. Boil the goods in camwood - two pounds of dyestuff to the ten of goods - for one hour, without any mordant, then wash them, and finish with an inidgo woad vat. This, by some dyers, is believed to be the best method of dyeing fast black on woolen goods. The oldest plan has been to dye the blue color first on the goods, then to dye a black on the top, in the manner described in article 29, with the addition of some madder to the logwood, and abuot one handfull of sumac to each ten pounds of wool.

Camwood Black. - Boil ten pounds of woollen goods for one hour in two pounds of camwood and one of fustic, then lift them, an introduce eight ounces of copperas, and boil for twenty minutes. Take them out of this, air them for fifteen minutes, and then wash them. after this they are boiled in a clean liquor with four pounds of logwood for one hour, and then lifted. Four ounces of copperas are then introduced into the kettle, and the goods boiled for half an hour longer, after which they are lifted, washed, and dried. Some dyers use one pounds of madder and one of camwood, with a handfull of sumac, instead of using camwood altogether.

Chrome Black. - Within fifteen years the bichromate of potash has come into extensive use in dyeing black colors on white woolen goods. Prepare the goods - 10 lbs. - by boiling them for one hour in six ounces of the bichromate of potash, three ounces of alum, and two of red tartar (argol.) They are then lifted, aired, and rinsed in two clean waters. Into a clean kettle, five pounds of logwood and half a pound of camwood are introduced, and the goods boiled in this for an hour and a half, when they are lifted, washed, and dried. This is a blöue black, and has not that depth of shade belonging to the other processes. By avoiding the use of alum and tartar in the mordant, and giving some fustic and more logwood, jet black is produced.

The use of sumac must be carefully attended to in woolen dyeing. Excepting for blacks and drabs, it should never be employed, and for these colors only a very limited quantity. Some dyers have supposed that because sumac and copperas make a black solution in water, that the same results can be obtained by the use of these substances on woolen dyeing, but this is a mistake. - Woolen goods boiled in sumac assume a rusty brown color, and are so altered in their nature by the tannin of the sumac, as to repel every effort to dye them a good black. Excepting in very minute quantities, sumac should never be used even in black woolen dyeing, as it is liable to injure the goods in appearance. it is often necessary to give weight for weight of logwood and goods for a good full black, and about one-fourth of the weight of fustic, to throw the color on the het shade. Some dyers use too much blue vitriol (sulphate of copper) in dyeing black on woolen goods; and out farmers' wives, when dyeing wool a black for home-made cloths, make the same mistake. Wool dyed black with a preparation of blue vitriol soon becomes rusty, and fades when exposed to sunlight and the atmosphere. This is owing to this salt of copper parting so easily with its oxygen. copperas of a dark dirty green color, free from peroxyd, is the best quality for use. In dyeing black on woolen goods, one ounce of it to the pound, with one-fourth of an ounce of blue vitriol, are about the proper quantities for the mordant. Verdigris is recommended by some dyers; but it is found in but few dyeshops; its use is far more limited now than it was fifty years since. Nut galls, hickory bark, and the rinds of walnuts are used in dyeing black on wool, but should in no instance be so used unless on the top of logwood; or with logwood when the goods have received and indigo bottom in a vat. None but the finest quality of black goods receive a dip in the woad vat, as this makes the color expensive. Almost all blackwoolen goods - broadcloths, narrow cloths, merino twills, delaines, &c. - are now dyed with the bichromate of potash preparation or mordant, and finished in a logwood and fustic liquor.

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