An anionic dye having substantivity for cellulosic fibres, normally applied from an aqueous dyebath containing an electrolyte
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A class of aniline dyes, so called because they have such great affinity for cellulose fibers, i.e., cotton and linen. While both these and acid dyes are sodium salts of dye acids, direct dyes do not require the use of a mordant. Their shades are duller than those of either acid or basic dyes and they tend to have less tinctorial value than the basic dyes; however, they have the very important advantages of being much more lightfast than the basic dyes and possibly more so than acid dyes
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