PRINTING IN COLOURS

the dyer; such materials as logwood, cochineal, and brazil-woodbeing introduced into Europe.

Coal-tar colours were discovered in the 19th century. In 1834Runge produced kyanol, and in 1856 W. H. Perkin introduced thefirst aniline colour, a mauve; this was followed two years later by amagenta, discovered by R. W. Hoffman, whose name is largelyassociated with naphthalene colours of which there is so wide arange. The alizarine colours were introduced by Graehe andLiebermann in 1868. Alizarine has now entirely superseded themadder which was so largely used for Turkey reds.

There are several methods of direct printing in colours uponfabrics : first, those which are at once fixed by the steaming process ;second, those in which the colours are produced either by firstprinting with a mordant, such as an acetate of alumina, then fixingand dyeing the cloth in a bath of colouring matter; or the cloth isfirst dyed all over, and the pattern is produced by the dischargingprocess, or a resist is printed on the cloth, which is then dyed.White or coloured patterns may thus be produced upon the colouredground. For instance, upon cloth dyed with indigo, the pattern isprinted with an alkaline chromate. It is then passed through a hotsolution of sulphuric and oxalic acid, which discharges the indigodye from the pattern. The same effect is produced upon Turkeyred by printing with a tartaric acid paste; the cloth is then passedthrough a solution of caustic soda to discharge the red.

The older processes of dyeing are still used extensively in theEast, and the beautiful reds from the kermes, yellows from weld,blues from indigo and woad, and browns from the walnut, give arange of harmonious colour, unapproachable even by the modernscientific dyer’s pallet, with its wide range of colours that have soenlarged the possibilities of colour printing; but as yet, they havenot exceeded the beauty, quality, and the durability of the olderdye-stuffs.

An early process of producing a pattern upon a coloured groundwas by covering portions of the fabric with clay or wax as a resist,or by tying small portions of the cloth with thread before beingdipped in the dye-vat.

India at an early date perfected a process known as bhandanawork, or “ tye and dye process ”—so called from the Hindu verbbkanda, “ to tie.” The pattern having been drawn upon the fabric, itis passed on to the knotter, who follows the design by pulling upthe cloth into minute portions and tying with thread, which success-fully resists the action of the dye when dipped in the vat.

This bhandana work is also used in the production of chind silks

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