A substantive dye or direct dye is a dye that adheres to its substrate, typically a textile, by non-ionic forces.

Overview

The amount of this attraction is known as "substantivity": the higher the substantivity the greater the attraction of the dye for the

fiber Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorpora ...

. Substantive dyes work best on textiles with high contents of cellulose, such as cotton. In contrast to direct dyes, wool and leather goods are dyed by the process of

ion exchange Ion exchange is a reversible interchange of one kind of ion present in an insoluble solid with another of like charge present in a solution surrounding the solid with the reaction being used especially for softening or making water demineralised, ...

, exploiting the cationic nature of proteins near neutral pH. The development of substantive dyes helped make mordant dyes obsolete. Substantive dyes are set in a slightly basic or neutral environment at temperatures close to boiling point. They are set by formation of aggregates of dyes within interstices of the fibres. Aggregation is enhanced by extended aromatic rings.Klaus Hunger, Peter Mischke, Wolfgang Rieper, Roderich Raue, Klaus Kunde, Aloys Engel: "Azo Dyes" in ''Ullmann’s Encyclopedia of Industrial Chemistry'', 2005, Wiley-VCH, Weinheim..

Gallery

File:Pontamine sky blue.svg,

Direct Blue 1 Direct Blue 1 is an organic compound that is one of many azo dyes. This salt is used as a substantive dye A substantive dye or direct dye is a dye that adheres to its substrate, typically a textile, by non-ionic forces. Overview The amount ...

. File:TrypanBlueSalt.png,

Trypan blue Trypan blue is an azo dye. It is a direct dye for cotton textiles. In biosciences, it is used as a vital stain to selectively colour dead tissues or cells blue. Live cells or tissues with intact cell membranes are not coloured. Since cells ar ...

(Direct Blue 14), which also exhibits medicinal properties. File:Direct Blue 15.svg , Direct Blue 15.

References

{{DEFAULTSORT:Substantive Dye Dyes