Direct Dyes and Disperse Dyes

Direct Dyes

Direct dyes are water soluble dyes. As the name suggests, these dyes are directly applied to the fabric from aqueous solution and are practically suitable for fabrics like cotton, rayon, wool, silk and nylon which from hydrogen bonds with water. Martius yellow and congo red are important example of this class of dyes.


Disperse Dyes

Disperse Dyes in the form of minute particles of a suspension diffuse into the fabric, get fixed and impart colour. Such dyes are used for dyeing synthetic fibres like polyesters, nylon and polyacrylo nitrile. Many anthraquinone disperse dyes are suitable for application to synthetic polyamide fibres.

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Acid Dyes and Basic Dyes

Acid Dyes

Acid dyes are usually salts of sulphonic acid and can be applied to wool, silk, polyurethane fibres and nylons. The affinity of acid dyes for nylon is higher than that for other types because polycaprolactum fibers fibers contain a higher proportion of free basic amino groups. Acid dyes do not have affinity for cotton. Orange-1 is a versatile acid dye.


Basic Dyes

Basic dyes contain amino group which in acid form water soluble salts. These dyes get attached to the anionic sites present on the fabrics. Such dyes are used to dye reinforced nylons and polyesters. Aniline yellow and malachite green belong to this class of dyes.


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