130. Indigo Blue Dye for Yarn

130.    Indigo Blue Dye for Yarn. The vats used for dyeing indigo blue are usually wine pipes or other large casks, sunk in the ground to a depth convenient for the operators to work at. Five of these constitute a set, and are worked together and kept of the same strength. The yarn being worked in quantities of 100 pounds, 20 pounds are passed through each vat.

Each vat is filled about three-fourths with cold water; there are then added 8 pounds of indigo, 16 pounds of sulphate of iron (copperas), and 24 pounds newly-slaked lime. The whole is well stirred with a rake for half an hour, and this stirring is repeated every 11/2 hours for the first day.

The time to stop the stirring is known by the solution becoming a rich oak yellow, having large blue veins running through it and a fine indigo froth on the surface. When these signs are all favorable, the solution is allowed to stand for several hours till all the solid matter settles, when it is ready for use.

The mode of dyeing consists in simply immersing the goods, and working them in the solution for 15 minutes, taking out and wringing or pressing, and then exposing to the air; repeating this operation until the desired depth of color is obtained. The yarn is then washed in cold water and dried. "When the shade required is very deep, the yarn may, previous to washing, be passed through a tub of water acidulated with vitriol till it tastes acid, and then washed; this adds brilliancy to the color.

131. Sky Blue Dye for Cotton Goods

131.    Sky Blue Dye for Cotton Goods. To dye 10 pounds of cotton, first bleach the cotton (see No. 125 (To Bleach Cotton Cloth)); then, to a tub of cold water sufficient to work the goods easily, add 1/2 pint nitrate of iron, and work in this for 20 minutes; wring out, and pass through a tub of clean water. Into another tub of cold water add 4 ounces ferrocyanide of potassium in solution, and about a wine-glassful of sulphuric acid; work the goods in this for 15 minutes; wring out and wash through cold water, in which is dissolved 1 ounce of alum; wring out and dry. For lighter or darker shades of blue, use less or more of the iron and ferrocyanide; or, should the color be too light after passing through the process described," add 1 ounce more ferrocyanide, repeat the operation through the same tubs, and the shade will be deepened nearly double.

132. Napoleon Blue

132.    Napoleon Blue. For 10 pounds cotton goods, the cotton must be first bleached.

Into a tub of cold water put 1 imperial pint of nitrate of iron and 2 gills hydrochloric acid, then add 3 ounces crystals of tin (or 1 pint chloride of tin); stir well and immediately work the goods in it for 30 minutes; wring out and put directly into the prussiate tub, made up with water into which is put a solution of 12 ounces ferrocyanide, and one wine-glassful of hydrochloric acid; work in this for 15 minutes, then wash out in clean water in which is dissolved 2 ounces of alum. If a deeper shade of blue is required, wash them in clean water without the alum, pass them again through the two tubs; and, lastly, wash them in water with the alum.