The subject may be divided into the following sections: -
The following summary of recipes for calico printing are in the main condensed from an article on the subject, by W. Crookes, F.R.S., in Spons" Encyclopaedia,'to which the reader may refer for greater detail and illustrations of machinery.
The pieces, before printing, are bleached in the most perfect manner. After the so-called "colours " have been printed on, the next step is " ageing." In this process, the goods are laid in bundles upon sparred floors, placed at different heights in the ageing house. The temperature is kept at 80° F. (27° C), the wet-bulb thermometer marking 76° F. (24 1/2° C). The ageing process may last 2 to 3 days; its object is the decomposition of the acetates of alumina and iron in the mordants, so that either the bases or hydrated subsalts are left attached to the fibre.
The next step is "dunging," whose purpose is the removal of the thickeners, which have now played their part. The process was formerly performed with cow-dung. This material has, however, been almost entirely superseded by the double phosphate of soda and lime, the arsenite and arseniate of soda, and the silicate of soda.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-dunging"; and the next, " second dunging." When silicate of soda is used, the goods pass through two cisterns, heated to 122° F. (50° C), or even 212° F.(100°C), 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 mor-danted for black only, purple only, or purple and black, the proportion of silicate of soda is reduced to 13 1/2 gal. at the same strength. The next step after washing is the dyeing with artificial alizarine, or anthrapurpurine.
The colour is now permanently attached to the mordanted portions; but the whites are still stained or soiled, and the pieces are therefore submitted 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 1/2 hour, with 1/4 to1/4 lb. soap. The pieces are washed in clean water after each soaping. The quality of the soap is of great importance: it should be quite neutral, and is made by preference from palm-oil. Freedom" from alkalinity is especially important for madder-purples.
(2) Washing in machine with cold water.
(3) Bath of oxy-muriate of tin: 1400 pints water, 10 lb. solution of tin per 10 yd.; time, 15 to 20 minutes; temperature, 133° to 143 1/2° F. (56° to 62° C).
(4) Washing in machine. (5) Second soap bath: 2100 pints water, 6 1/2 lb. soap; time 45 minutes; temperature, 201° F. (94° C). (6) Washing again in cold water. (7) Third soap-bath: proportions as in second. (8) Washing again in cold water. (9) Boiling in closed boiler, in 2100 pints water, 5 1/2lb. soda crystals, 5 1/2 lb. soap; time, 2 hours. (10) Washing in cold water. (11) Warm bath for 1/2 hour in water at 122° F. (50° C.).
By a " discharge "(enlevage), is understood a mixture which, if printed upon cloth previously dyed some uniform colour, e.g. Turkey-red, vat-blue, aniline-black, etc, destroys such ground colour, leaving a design which may be white, black, yellow, green, etc. The term " discharge style " is more especially applied to patterns of this nature obtained upon a Turkey-red. The following colours will serve as examples of these discharges: -
1 gal. logwood liquor at 4° Tw.; 2 lb. yellow prussiate; 1 qt. thick gum tragacanth water, 2 lb. flour. Boil, and add 2 qt. black liquor at 30° Tw. When quite cold, add 1 gill nitrate of iron at 80° Tw.
5 lb. tartaric acid, 1 gal. water, 1 gal. tin pulp, 2 gal. double muriate of tin at 120° Tw., 2 gal. gum tragacanth water.
(1) For cylinder work - 6 lb. tartaric acid, 1 gal. water, 1 1/2 lb. starch. (2) For block work - 10 lb. tartaric acid, 7 1/2 lb. China-clay, 1 1/2 lb. perchloride of tin, 1 pint gum water, 1 gal. water.
-(1) Block - 1 gal. lime-juice at 50° Tw., 4 lb. tartaric acid, 4 lb. nitrate of lead. When dissolved, add 6 lb. China-clay, 3 lb. gum Senegal. (2) Cylinder - Thicken the former with l 1/2 lb. starch, instead of gum and China-clay.
After any of these discharges is printed on, the pieces, when dry, are passed through the "decolouring vat," which is made up of 1000 gal. water and 1000 lb. chloride of lime, well raked up, and freed from lumps. A double set of wooden rollers at top and bottom is placed in the vat, and the liquid is kept constantly stirred up, so as to be uniform. The pieces are now allowed to run through the liquor at the rate of 28 yd. in 3 minutes. On leaving the vat, they are run between squeezing-rollers into water, and are then rinsed for 10 minutes in solution of bichromate of potash at 4° Tw. Wash in pure water, then in water soured with muriatic acid, and lastly in pure water; after this, dry. Except where the discharge was printed on, the Turkey-red is unaffected; but there, it is removed, and either the ground is left white, or a mineral colour takes its place.