mordant

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mordant

(môr`dənt) [Fr.,=biting], substance used in dyeing to fix certain dyes (mordant dyes) in cloth. Either the mordant (if it is colloidal) or a colloid produced by the mordant adheres to the fiber, attracting and fixing the colloidal mordant dye (see colloidcolloid
[Gr.,=gluelike], a mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance. The mixture is also called a colloidal system, colloidal solution, or colloidal dispersion.
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); the insoluble, colored precipitate that is formed is called a lakelake,
in dyeing, an insoluble pigment formed by the reaction between an organic dye and a mordant. The color of a lake depends upon the mordant as well as the dye used. Generally, lakes are not as colorfast as many inorganic dyes, but their colors are more brilliant.
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. The chemical compounds used as mordants are either acidic or basic. Acid mordants (e.g., tannic acid) are employed with basic dyes; basic mordants (e.g., alum, chrome alum, and certain salts of aluminum, chromium, copper, iron, potassium, and tin) are employed with acid dyes. Cloth to be dyed may be treated first with the mordant and then with the dye, or the mordant and dye may be applied together. The vividness of certain dyes that ordinarily do not require the use of a mordant may be markedly increased when one is employed.

mordant

[′mȯrd·ənt]
(chemistry)
An agent, such as alum, phenol, or aniline, that fixes dyes to tissues, cells, textiles, and other materials by combining with the dye to form an insoluble compound. Also known as dye mordant.