Home › Aniline Colors › To Remove Aniline Colors

To Remove Aniline Colors

There are various ways proposed to remove aniline colors, the following being the simplest and most practical. Goods dyed with aniline colors may easily be rendered white by the use of zinc gray; the metallic zinc contained in this powder reduces the colors, forming also found this to be the case with red aniline soluble colorless products. To apply the colors, such as fuchsine, rubine, &c., the adul- principle, triturate 100 grains zinc gray with teration amounting in some cases to as much 50 grains mucilage marking 20° Baumé, until as 50 per cent. The amount of sugar present can be ascertained by treating a sample of the suspected dye with absolute alcohol; or, still better, with a mixture of alcohol and ether; the sugar will remain undissolved. the mixture is homogeneous; incorporate with this 20 grains of a solution of hyposulphite of soda marking 20° Baumé, apply this mixture directly to the goods, let it dry and vaporize. After this operation it is best to wash the goods with water slightly acidulated 2562. To Remove Sugar from Aniline Dyes. If it be found by the test given with hydrochloric acid. Cotton goods may in No. 2561, that an aniline color has been be bleached by chlorine or bleaching liquor, adulterated with sugar, this may be removed but this is not applicable to other than cotton by repeatedly washing the color with cold fabrics. water, which will dissolve the sugar.

Another simple method consists in digesting the fabrics for a sufficient length of time solved until the solution shows 2º Baumé; in 90 per cent. alcohol, which usually com- for the wool the mordanting bath should be pletes the decolorization in a short space of at a boiling heat, and the goods should also time. The same alcohol can be used several be placed in a warm bath of tannin 90° Fahr. times in succession, and can afterward be puri- for half an hour. In dyeing, a hot solution of fied by rectification or redistillation, so as to the color must be used, to which should be involve but little loss. The work is best done added, in the case of the cotton, some chloride in a well-covered copper kettle, which is to be of zine, and, in the case of the wool, a certain set in boiling water. A little hydrochloric amount of tannin solution. acid may be added if the articles are not too 2569. To Dye Aniline Opal Blue on delicate, thereby increasing the solubility of Cotton. To mordant the aniline color known the aniline colors. as opal blue upon cotton it is recommended If all other methods fail, cyanide of po- to rinse the goods, after bleaching, in a dilute tassium is absolutely certain. A stone vessel solution of soda crystals, to neutralize the is to be selected, in which a small quantity of acid of bleaching, then to pass them into a cyanide of potassium is to be introduced, and hot bath of soap, in which oil exists in emulhot water poured upon it, so as to make a so- sion in these proportions: Water, 100 liters (211 lution of to 1º Baumé. The whole is to pints); soap, 8 kilos (21 pounds troy); oil, be stirred well with a long and strong glass 2 kilos (5 pounds troy). Wring them out, rod, and the operation conducted in the open dry, and pass them into a solution of acetate air, so that no harm may result from the con- of alumina of about 40 or 5° Baumé, wring densation of the vapor. The fabric in question, out, dry, and rinse in hot water. Finally dye previously well cleaned, is now placed in the in a solution of opal blue to which acetic acid vessel, and pushed under the liquid with the has been added. The temperature of the dye glass rod, and the top of the vessel laid on. bath should be 75° to 90° Fahr. Rinse and It is advisable to keep the solution warm, by dry. immersing the stone vessel in a wooden tub 2570. Difficulty in Dyeing Cotton with properly supplied with steam or hot water. Aniline. This difficulty consists in the ir- After a short time the lid should be removed regularity of intensity of color when the aniby taking it off at the end of a long handle, line colors are applied. This effect is attriallowing the vapors to pass off before the buted to the unequal oxidation of the tin salts operator comes near. By means of the glass applied before dipping the goods into the dye rod the cloth is to be lifted, and if not entirely bath; in using these colors, avoid the use of white, is to be replaced and the process con- | the tin salts, which have little or no beneficial tinued still longer. When finished the cloth effect on the results in any case; and dip the is to be transferred by means of the glass rod goods into the dye bath, after treating with to a large vessel containing hot water, and infusion of nut-galls or sumach. If tin must stirred around for a time, then removed and rinsed off. The solution of the cyanide of chloride. potassium can be used several times without losing its power. Cyanide of potassium is a deadly poison; contact with any sore or cut is extremely dangerous, and inhaling its va- chlorate, and bichromate of potassa, it yields por is sudden death. 2566. To Remove Stains of Aniline from the Hands. The best way to remove such stains from the hands is to either wash them with strong alcohol, or what perhaps is more effectual, to wash them with a little bleaching powder, and finally with alcohol. be used, the best salt of that metal is the bi-