With respect to the method of bleaching such fine goods, it is very similar to those given, the amount of lime, soda, &c., being reduced to suit the texture of the materials. The following process for 1000 lb. cloth may be taken as a type, using low-press kiers 1. Wash, boil in water 3 hours, and wash.
2. First soda boil : 70 lb. soda ash, 20 lb. soft soap, boil 6 hours and wash.
3. Second soda boil : 50 lb. soda ash, 20 lb. soft soap, boil 3 hours, and wash.
4. Chemick : bleaching powder solution p Tw., steep 2 hours, wash.
5. Sour : hydrochloric acid 1° Tw., steep 2 hours, wash.
6. Third soda boil : 30 lb. soda ash, 20 lb. soft soap, boil hour, wash.
7. Chemick, as before.
8. Sour, as before, and wash well.
With the market bleachers, a most particular part of their work, as important as the bleaching itself, consists in " finishing " the goods to suit the tastes of the various merchants and markets, and in imparting a fine appearance to the fabric. This embraces starching, damping, calendering, beetling, stentering, and folding, one or more of these processes being employed, according to the " finish " required.
Starching.—For the thicker fabrics, cambrics, &c., the so-called "starching mangle '' is used in this process. It is very similar to the older kind of " squeezer," and consists of a pair of heavy rollers, one of compressed cotton yarn snd the other of brass, the lower one dipping into a decoc tion of starch contained in a wooden trough below. The cloth is drawn at its full width between the rollers, acquiring au excess of starch, which is at onee expressed ; it is then generally ruu directly over the drying cylinders, and folded. There are other maohines, so adapted that the starch is only put upon the wrong side of the cloth. This method is used when the cloth is of low quality ; the starch is mixed with a large percentage of " filling " (china clay, &c.) for the pur pose of filling up the pores, and giving weight and false solidity of appearance to the fabric. Ouo arrangement by which this is effected consists of a coarsely pin-engraved copper roller, on to which the passing cloth is depressed. The copper roller revolves in a direction contrary to that of thc cloth, and is coated. with the starch mixture by a furnisher or wooden roller revolving in
contact with it, or by dipping into thc starch itself. The excess of starch on the copper roller is scraped off by a steel blade before it touches the cloth, so that the starch remains only in the engraved parts. In this manner, the starch is, as it were, printed, on to the hack of the cloth. Another method is to depress the cloth on to a pair of rollers revolving in the starch mixture ; the oloth plastered with an excess of starch, which is then spread and partly scraped off, by passing tho cloth over a steel blade. The two rollers can be adjusted at any distance from each other, so as to regulate the quantity of starch passing between them and coating their upper surfaces. Figs. 358 and 359 represent these two methods ; R R are the depressing rollers, A A the starching rollers, E the pin-engraved roller, B B the steel blades, S S the starch boxes.
When the starching is done on one side only, it is usual to have the first few upper drying cylinders replaced hy reels, and so to thread the cloth that only the unstarched side of the piece touches the drying cylinders, till the middle of the machine is approached, when the cloth is partly dried. This prevents the starch from stioking to the cylinders, and coming off again in lumps on to the pieces, thus spoiling their appearance. The same or a similar arrangement is used when the cloth has a raised woven pattern, e. g. brilliants, brocades, &c. ; in this case the figured side of the cloth is not allowed to touch and be flattened against the drying cylinder ; thus the raised figure is preserved.
The starch itself is a decoction of wheat, rice, sago, or other starches, according to the finish required, mixed with a little ultramarine, indigo, or aniline blue, to remove the yellowish hue of the white. If necessary, the " filling'' already mentioned is added, also a proportion of soapy and waxy matters, which serve to render the goods soft to the feel, or capable of receiving a high lustre in the subsequent calendering.