Application of acid dyes to silk :- (Part 2)
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Application of acid dyes to silk:-
Most acid dyes can be advantageously dyed from a broken soap bath. For the purpose some of the soap liquor obtained from boiling off the silk (boil-off liquor) is diluted with 2-4 parts of water and then made acid with acetic, formic, or sulphuric acid according to the leveling and exhausting properties of the dye. The previously boiled-off silk goods are entered at 105-1220F, the temperature is raised gradually to the boil and boiling is continued until the required shade has been attained. If necessary, more acid can be added toward the end of the dyeing period for exhaustion of the dyebath. Both skeins and piece goods can be processed in this way.
The dyed silk goods are rinsed well and then gradually finished by treatment in a fresh bath with sulphonated oils or other finishing agents. Scroop, that rustling sound so widely associated with silk dress goods in Victorian period, can be imparted to dyed silk by first impregnating the goods with a soap solution and then treating them in an acid bath containing an orgainic acid such as tartaric, citric or lactic acid.
