YOUR DRESS

Hokitika Guardian, 7 May 1921, Page 4

YOUR DRESS

HOW IT GETS ITS COLOUR

(By a Dye Chemist). In England it is not customary for cotton mills to be equipped with bleaching and dyeing plant. Merchants buy the raw or grey fabric .from the manufacturers and send it elsewhere to be dyed and finished. Grey cloth arrives at the dyers in pieces which arc usually 80 to 100 yards in length and about 30 inches wide, it contains various oils and starchy ma terials which have been used to assist the spinning and weaving, and these have to he removed before dyeing.

The pieces are stitched together so as to form a continuous • band and are rapidly passed, so as to avoid scorching, over a red-hot copper-plate. They then pass through a bath of water and aie coiled into large, square stacks. By this treatment the loose fibres on the surface of the cloth, which would interfere with the finishing process, are singed off. The wet fabric is generally allowed to lie overnight so as to loosen the impurities which have to be removed. It is then saturated with lime water find packed into kiers, which resemble large boilers placed on end. Boiling water is continuously circulated through the fabric for a few hours, when the fabric is removed and treated with acids to ie move the lime.

The fabric is again returned to the kier for a further four hours’ boiling with water containing washing soda. It is then removed and washed free from the chemicals used.

At this stage the cloth is t obtained free .from all impurities, hut it is slightly tinged with yellow owing to the presence of the natural colouring matter of the cotton fibre. By treatment with bleaching powder (chloride of lime) a perfectly white fabric ready for dyeing is obtained. Dyeing is generally carried out on jigs, which are V-shaped tanks in which the dye liquor is placed. Arrangements are fitted so that steam can he blown into the bottom of the jig to heat up t! e dye liquor when necessary. There ’s n roller on either side of tbe jig-

The fabric is wound full width from

one roller to the other, passing through the liquor and under a small roller fixed

in the bottom of the jig- By thus passing the cloth backward and forward

through the dye liquor the desired shade is obtained. * The foreman dyer directs the dyeing according to the pattern he has to match.

After dyeing, the fabric is washed in the same jig. mangled, and then dried by a passage over twenty or thirty large revolving eopper-evlinders. These are hollow, so that they may he heated with steam. Their hot surface rapidly dries cloth in contact with it.

It is this stage that decides whether the dyer shall he happy or otherwise. As the cloth leaves the drying cylin-

ders all stains and unevenly dyed parts become visible. Badly dyed cloth is returned for another bleaching and redyeing, hut it can never he so satisfactory as elotli dyed correctly the firsttime. The necessary width is obtained by passing the elotli through a stretching

machine. The finished cloth is cut up into suit able lengths, packed, labelled, and re

turned to tbe merchant and owner