Calendering

Calendering, a corruption of the word cylindering, is the process of finishing textile fabrics for sale, imparting to them a lustre and polish, which is technically termed "glaze." Before calico or cotton cloth can be printed (q.v.) it has to be calendered, an even surface being thus produced, the irregularities of the weaving and the rounded threads being flattened down. A calender has been compared to the domestic flat-iron, and the old-fashioned mangle, for its work is similar. The complicated geared machine, however, bears no resemblance to either. It consists of a series of cylinders, superimposed in a vertical iron frame, and with the pressure regulated by screws and levers. These cylinders, or rollers, have not only to furnish pressure, but friction, heat, and moisture as required. They are, therefore, arranged on different plans, and the materials of which they are made may either be metal, cotton, or compressed paper, which will not warp nor split under the alternating influences of heat and cold as wood will do. A "three-bowl" calender usually has its middle cylinder of metal. Such a machine is used for dressing gauzes, muslins, and lawns, which are passed between the cylinders cold. In another calender one of the rollers may be heated with steam, or gas, or a red-hot iron placed within it, the heat being necessary, for example, to put a finish or a glaze to paper. In silk moires the water surface is obtained by the medium of the calender. To produce imitations of leather for bookbinding engraved bowls are employed in combination with paper cylinders, the one fitting accurately into the other. Calendering is also resorted to by jute and linen manufacturers, steam laundries, and the makers of indiarubber, to roll their material into sheets. The chief centres of the industry are in Manchester, Glasgow, and Dundee.