acid dyes
A very large class of dyes containing acidic
groups, such as the sodium salts of sulfonic acids
or phenolic groups. They are more soluble and have
less tinctorial value than BASIC DYES but they
also have greater light fastness. See: FAST COLORS . They do
not form lakes with tannin. Acid dyes are used in
dyeing leather, paper, etc., and their particular
value lies in their ability to produce brighter,
more uniform colors. They are normally applied
from an acid dye liquor (acetic, formic, or
sulfuric acid); however, unless applied from a
neutral or only slightly acid dyebath, i.e., pH of
6.0 to 7.0, their use is likely to result in acid
degradation of the material dyed. See also: FUGITIVE COLORS ; LAKE .
(17 , 67 , 72 , 363 )
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