Patterns in indigo may also be produced with the vat. Either certain reserves (resists) are first printed on, and the pieces are then vatted ; or the cloth is first died a uniform blue, and discharges are afterwards printed on to form the design. Examples are given of the mixtures used for both purposes.
White reserve (block).—Blue-stone, 3 lb.; water, 1 gal. ; pipe-clay, 15 lb. Beat up with some of the solution ; mix gradually to a smooth paste, and add thick gum senegal water, 1 gal. ; and muriate of copper at 80° Tw., 1 qt.
White reserve (machine).—Blue-stone, 2i lb, ; water, 1 gal. ; flour, 9 lb. ; British gum (dark), 2 lb.
White resist (for lighter vat-hlues).—Dark British gum, 25 lb. ; water, 15 lb. Boil for 10 minutes ; and add soft-soap, 71 lb. When thoroughly incorporated, add sulphate of zinc, 20 lb. Stir in well, and add further :—Water, 71 pints ; pipe-clay, 10 lb. ; nitrate of copper at 80° Tw., 71 gal. Work all thoroughly together.
Orange reserve.—Heat 2 lb. water to a boil, and add, with constant stirring, 1 lb. sugar of lead, and lb. litharge ; boil for 20 minutes, and add to the liquid, to which more water must be supplied, to compensate for the loss by evaporation, 1 lb. blue-stone, 2 lb. nitrate of lead, and 11 oz. verdigris, previously softened in acetic acid. The whole is let stand for a day, with frequent stirring; 1i lb. powdered gum senegal, and 1 lb. sulphate of lead, are then stirred in ; and lastly, 21 oz. powdered sal-ammoniac, and 1 oz. lard, are added. If the colour is too stiff, it is diluted with water. It is then strained, and printed on at about 50° (122° F.). Age for a day or two at 19°-25° (66°-77° F.). Dye in the cold vat ; dry, and sour at /° Tw. For raising the orange, take for 100 yds., 175 pints water, containing 8 lb. chromate of potash, and 16 lb. lime. Let settle ; run off the clear, and heat to a boil, at which temperature the pieces are passed through at such a speed that each part may occupy 3 minutes in traversing the liquid. Rinse well.
Yellow reserve.—Blue-stone, 20 lb. ; water, 2 gal.; nitrate of lead, 20 lb. Dissolve ; and thicken with flour, 12 lb. ; sulphate of lead pulp, 2 gal. Boil well together.
The sulphate of lead pulp here mentioned is the sediment left on making red liquor with solution of sugar of lead and alum (or sulphate of alumina), after the liquid has been run off.
To produce a pale-blue pattern on a deep-blue ground, the entire pieces are first dyed a light shade in the vat. They are then withdrawn, thoroughly washed in water, taken through vitriol sours at 2° Tw., washed again, squeezed, and dried. One of the white reserves is then printed on, and the pieces are returned to the vat, and dyed the darker shade. The reserved parts appear as a pale-blue pattern on a deep-blue ground.
To obtain a design in two blues on a white, muriate of manganese is printed on, thickened with dark British gum, and is then peroxidized by being passed through chloride of lime and soda, as in the production of " bronzes." The goods are then dried, and those parts of the pattern which are to appear white are printed with a white reserve. The goods are next limed, vatted to shade, taken out, aired to oxidize the indigo, washed, and rinsed in weak muriate sours, to which a little protochloride of tin has been added. The pattern appears then in white and dark-blue on a light blue ground, the white being where the discharge was applied, and the dark-blue where the indigo is fixed upon a bottom of manganese brown.
If yellow or orange is to be obtained in addition, the yellow or the orange reserve (see above) is blocked in beside the muriate of manganese and the white reserve. Vitriol sours must be used here, and the yellow is then developed by a passage through bichromate of potash at 38° (100° F.) containing 2 oz. a gal. Wash in water, and pass through muriate sours at i° Tw., with the addition of 1 oz. oxalic acid a gallon.
If a blue and green design is intended, the yellow discharge above given, or one of a similar character, is printed on, and the goods are dipped in the vat to a full blue, washed, aired, washed again, taken through vitriol sours, at 2° Tw., washed again, and passed through the bichromate beck, but without any treatment in oxalic-muriatic sours. The green is formed by the combination of the yellow and the blue.