Dark Red (for resisting a chocolate cover).—Resist-red liquor (see below) at 18° Tw., 12 gal. ; flour, 24 lb. Boil well, and when almost cold, add 12 lb. tin crystals.
The resist-red liquor consists of acetate of limo at 24° Tw., 90 gal. ; sulphate of alumina, 272 lb. ; ground chalk, 34 lb.
Red (for resisting purple covers).—Resist-red liquor at 14° Tw., 6 gal. ; flour, 12 lb. Boil ; when nearly cold, add 2+ lb. tin crystals.
A " cover" is a small pattern in purple, chocolate, ate., applied over the whole surface of the piece. The "resisting reds" above mentioned prevent it from becoming fixed to those portions of design where they are applied, and where, therefore, a red is produced.
White figures are obtained by printing on some mixture like the following :—Lime-juice, at 8°, 20°, or 30° Tw., 1 gal.; starch, 1 lb. Boil, and stir till dissolved. Where this so-called " acid " is printed in, covers and padded grounds subsequently printed take no effect, and the figure remains white. Upon such whites, steam colours (see below) may be afterwards blocked in, and thus a great variety of effect is obtained.
Chrome Standard—Boiling water, 2 gal.; bichromato of potash, 8 lb. Dissolve, and add muriatic acid at 32° Tw., 11 gal. Stir gradually in 3+ lb. sugar.
The pieces, before printing, are bleached in the most perfect manner. After the so-called " colours " have been printed on, the next step is " ageiug." In this process, the goods were formerly hung up in single folds in enormous rooms, maintained at the proper degrees of warmth and moisture. They are now laid in bundles upon sparred floors, placed at different heights in the ageing house. The temperature is kept at 27° (80° F.), the wet-bulb thermometer marking 244° F.). For this purpose, . large iron steam-pipe runs under the flooring, and steam is allowed to enter directly into the house from a number of small jets. Double windows and doors, a double roof, and thick walls serve to guard against sudden changes of temperature ; but proper ventilators are fixed, to allow the vapours of acetio acid, given off, to make their escape. The ageing process may last 2-3 days ; its object is the decomposition of the acetates of alumina and iron in the mordants, so that either the bases or hydrated submits are left attached to the fibre.
The next step is " dunging," the purpose of which is the removal of the thickeners, which have now played their part. The process, which is known in French as digononage or bousage, was formerly performed with cow-dung. This material has, however, heeh almost entirely super seded by the double phosphate of soda and lime, the arsenite and arseniate of soda, and the silicate of soda. The pieces are passed through warm but weak solutions of these substances. This
operation is often performed twice, the first time being called " fly-chinging " ; and the next, "second dunging." When silicate of soda is used, the goods pass through two cisterns, heated to 50° (122° F.) or even 100° (212° F.), containing 738 gal. water and 19 gal. silicate of soda at 14° Tw., if the goods have been mordanted for brown and red, black and red, brown only, red only, and rose on a white ground. But if mordanted for black only, purple only, or purple and black, the proportion of silicate of soda is reduced to 13+ gal. at the same strength. The next step after washing is the dyeing, formerly with madder-root, or some of the extracts of madder, but now with artificial alizarine, or anthrapurpurine. The colour is now formally and permanently attached to the mordanted portions ; but the whites are still stained or soiled, and the pieces are therefore sub mitted to the clearing process (avivage), which consists in successive treatments with soap-lye. A common treatment is two soapings at a boil, each time for + hour, with 1-+ lb. of soap. The pieces are washed in clean water after each soaping. The quality of the soap is of great import ance : it should be quite neutral, and is made, by preference, from palm-oil. Freedom from alkalinity is especially important for madder-purples.
The following prooess has been employed in Alsace for clearing roses and reds :—(1) Soap bath : water, 1200 litres ; white curd-soap, 4 kilo. per 900 metres ; time, 1+ hour ; temperature, 50° F.). (2) Washing in machine with cold water. (3) Bath of oxy-muriate of tin : water, 800 litres ; solution of tin, 4.5 litres per 900 metres ; time, 15-20 minutes; temperature, 56°-62° F.). (4) Washing in machine. (5) Second soap-bath : water, 1200 litres ; soap, 3 kilo.; time, 45 minutes; temperature, 94° (201° F.). (6) Washing again in cold water. (7) Third snap-bath : proportions as in second. (8) Washing again in cold water. (9) Boiling in closed boiler, in water, 1200 litres ; soda crystals, 2i kilo. ; soap, 2i kilo.; time, 2 hours. (10) Washing in cold water. (11) Warm bath for hour in water at 50° (122° F.).
Grass-bleaching is occasionally used in the clearing process for chintzes, cretonnes, &c., as it is considered to render the shades more transparent.
The clearing process has been very much simplified in consequence of the introduction of artificial alizarin°.