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PREPARATION OF CLOTH FOR PRINTING
Goods intended for calico-printing ought to be exceptionally well bleached, otherwise mysterious stains, and other serious defects, are certain to arise during subsequent operations. Particulars of bleaching will be found in the article BLEACHING (q.v.).
The chemical preparations used for special styles will be mentioned in their proper places; but a general " prepare," employed for most colours that are developed and fixed by steaming only, consists in passing the bleached calico through a weak solution of " sulphated " or turkey red oil containing from 2 per cent. to 5 per cent. of fatty acid. Some colours are printed on pure bleached cloth, but all patterns containing alizarine red, rose and salmon shades, are considerably brightened by the presence of oil, and indeed very few, if any, colours are detrimentally affected by it.
Apart from wet preparations the cloth has always to be brushed, to free it from loose nap, flocks and dust which it picks up whilst stored. Frequently, too, it has to be " sheared " by being passed over rapidly revolving knives arranged spirally round an axle, which rapidly and effectually cuts off all filaments and knots, leaving the cloth perfectly smooth and clean and in a condition fit to receive impressions of the most delicate engraving. Some figured fabrics, especially those woven in checks, stripes and " cross-overs," require very careful stretching and straightening on a special machine, known as a " stenter," before they can be printed with certain formal styles of pattern which are intended in one way or another to correspond with the cloth pattern. Finally, all descriptions of cloth are wound round hollow wooden or iron centres into rolls of convenient size for mounting on the printing machines.