Dyeing of cotton, Linen, Rayon, Wool, Silk and Mis
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Dyeing of cotton, Linen, Rayon, Wool, Silk and Miscellaneous Fibres:-
Cotton linen and rayon must be mordanted before application of a basic dye.Cotton and rayon are mordanted with tannic acid by working the goods for 15-30 min. in a bath set at 140-1850F with 1-6% of tannic acid owf, according to the depth of the dyeing to be applied later. The goods are allowed to remain in the cooling bath for some time, preferably overnight. They are then squeezed or extracted and treated for 20-30 min. in a cool bath set with half as much tartar emetic as tannic acid. The treated goods are rinsed well and either dyed at once, or dried for future use. Standing baths (baths used for several successive dyes, with additions of reagents) are advantageous for the tannic acid.
For application of synthetic mordant to cotton or rayon, the bath is self at 160-1800F with 1.5-6% owf of synthetic mordant solution according to the depth of the dyeing to follow and to the length of the mordanting bath. Rayon requires less mordant than cotton. The bath should contain 0.5% owf of a nonionic dyeing assistant to keep the bath free from scum. After the good have been worked for about 10 min. 5-40% of common salt owf, according to the depth of the mordant and the length of the bath, is added and application is continued in the cooling bath for 50 min. more. The goods are lifted and rinsed well in a cold solution containing 0.5% of 28% acetic acid and 2% of salt owf. For economy in extensive application, standing baths are employed.
