When cotton cloth comes from the loom, with the exception of coarse, unbleached muslins, it is by no means ready for the market. If the yarn has been bleached and dyed before weaving, then the cloth must be inspected, mended if necessary, knots cut off, and the fuzzy ends singed off from the surface by passing rapidly through a gas flame. It must then be soaped and washed, starched, and finished by heavy pressing in a mangle or by a calender. The calender is a heavy pressing machine used to give smoothness and luster. A variety of finishes may be produced by the calender, the construction of the rolls through which the cloth passes, the pressure, the friction, the temperature, and the starch, all having their part in determining the finish. Winding and measuring finally prepare the cloth for market.
Cotton which goes to the market in the "brown" state goes through but one process of finishing, namely, brushing. The brushing machine is a combination of emery rolls, card rolls, and beaters, which remove the motes, knots, nubs, lint, dirt, etc., from the cloth.
If the yarn has not been bleached and dyed before weaving, this is done before starching and pressing the finished cloth.
Printing is the process of stamping a design on the surface of the cloth, or on the warp, before weaving. The processes of bleaching, dyeing, and printing will be described in a separate chapter. Printing is used for the production of calicoes, percales, dimities, organdies, and many other figured cotton cloths. Dyeing in the yarn is used for ginghams, and dyeing in the piece may be used for materials which are a solid color in the finished state.
This is but a brief sketch of the processes in the manufacture of a plain piece of cotton cloth. Corduroys, crepes, flannelettes, and dozens of other kinds of material are much more complicated in weave and finish. Further particulars may be had by consulting reference books, if it is not possible to visit mills, where the process may be much more easily understood.
It will readily be seen that because of the cheapness of the cotton fiber it will not be adulterated with woolen, silk, or linen; jute and hemp, while cheap, are not suitable for such adulteration. The points which the buyer must consider are the adulteration with starch, the finish which may wash off, and the color, design, and quality of the material.
Fig. 19. Mercerized Cotton Fibers.
Mercerized Cotton is a comparatively recent product put upon the market. In 1844, John Mercer discovered that by treating the cotton fiber first with alkali, then tension and rinsing with water, the fiber swelled, straightened out, and gained much in luster; it also gained something in strength and m its power to absorb dyes. It is only within the last fifteen years or so that this process has been used commercially, but the manufacture of mercerized cotton is now a very important part of the cotton industry.
Caustic soda is the alkali used, and the process should be carried on away from the air, either at room temperature or artificially cooled. The tension may be applied during the treatment with alkali or later, but must be applied when the cotton is rinsed, otherwise the fiber shrinks and becomes transversely wrinkled. The physical change is merely straightening the twist of the cotton and swelling the fiber so that it becomes very smooth and reflects light, thus giving it luster. The chemical change is first from cellulose to alkali cellulose, then to cellulose hydrate. The mercerization is lasting, and is not removed by washing. An artificial luster may be obtained by heavy calendering, but this is not lasting. Mercerization may be accomplished in the yarn or in the woven cloth. It is probably more complete when done in the yarn, because of more even tension.
Mercerized cotton should command a higher price than ordinary cotton because it has an increased value and is more expensive to produce; therefore one should be sure that cotton is really mercerized and not merely calendered to give it the appearance of mercerized cotton. The use of mercerizing has broadened the field of usefulness of cotton and added new materials of increased beauty and serviceability to the many varieties of cotton cloth already on the market.
Barker, A. F. Textiles.
Batchelder, S. Cotton Manufacture.
Bowman, Fred H. Structure of the Cotton Fiber.
Brooks, C. P. Cotton.
Chapman, S. J. The Cotton Industry and Trade.
Cotton Plant, The. Bulletin 33, Department of Agriculture. Office of Experiment Stations, Washington, District of Columbia.
Dana, W. Cotton from Seed to Loom.
Marsden, R. Cotton Spinning.
Marsden, R. Cotton Weaving.
Matthews, J. M. Textile Fibres.
Posselt, E. A. Wool, Cotton, Silk, from Fibre to Finished Fabric.
Thompson, Holland. From the Cotton Field to the Cotton Mill.
Wilkinson, F. Story of the Cotton Plant.