Hummel, J. J. (John James), -1902 · London [etc.] New York, Cassell & Company, Limited · leaf 321
301 Chap. XIII.J INDIGO. The pieces are passed through a series of rollers, arranged on a wooden frame immersed in the vat A. At the point of exit they pass through a pair of squeezing rollers, and are then led over a similar system of rollers B, outside the vat, for the purpose of oxidation. The… … may be repeated two or three times, according to the in- tensity of colour required. After leaving the vat, the pieces are first rinsed in cold water, to remove the loose lime and Indigo adhering super- ficially, and then in dilute sulphuric acid, 4° — 8° Tw. (Sp. Gr. T02 — 1’04), to dissolve ofi‘…
Dyes and dyeing
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