Dyeing Processes with Different Classes of Dyes

3 Dyeing Processes with Different Classes of Dyes 

Because of their good leveling properties, acid dyes are used for medium shades up to ca. 1/1 standard depth of shade. For deep and dark shades metal-complex dyes are preferred, because of their high fastness level, though they tend to nonlevel absorption and structure-related stripiness. 

Basically, the same sulfonated acid dyes which are used to dye wool are also suitable for polyamide (see Sections 4.10.2-4.10.4). In a weekly acidic dye liquor the sulfonate anion of the dye binds to the ammonium cation, formed from the amino end groups of the fiber. Affinity to the fiber can be increased by introducing addi- 

Dye selection depends on technical requirements. Monosulfonated acid dyes comprise leveling dyes and neutral absorbing dyes they can easily be combined with each other. Disulfonated acid dyes produce dyeings with good wetfastness. They are used as self-shades but are not recommended for three-color combinations [100]. 

The dyeing behavior of acid dyes can be described with the help of the combination values K, which are derived from combination dyeings at 70, 80, and 90°C. The K values of dyes from different dye manufacturers cannot be compared [101]. 

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