More on the Application of Basic Dyes

Dyes in the form of a free base are known of in a few cases. Methyl Violet, Magenta, and some other colors made by the "melt" process, are in a crystalline form, while most of the basic dyes manufactured by other methods are in the form of powders. In a dye-bath, basic salts seem to separate into an acid and a dye base.

When dyeing animal fibers, such as wool or silk which seem to possess acid properties the dye base combines with the fibers and acid is left in the bath. When cotton is dyed with these dyes, the dye base combines with the acid mordant. Cotton requires a previous preparation in a tannic-acid bath, called a mordant.

You can mordant of vegetable fibers, such as cotton and linen, by steeping the material to be dyed in a cold tannin bath for several hours, and fixing in a tartar emetic or following the treatment of passing the goods through a solution of some metallic salt, such as antimony potassium tartrate.

Insoluble tannates of antimony or some other metal are finally formed. Wool and silk because of their acid reaction are dyed with basic dyes in a neutral bath without previous treatment. Brighter colors in wool and silk fabrics are sometimes obtained from basic dyes by adding about 2% soap to the dye-bath.

Basic dyes are not as valuable to the dyer of textile fibers as formerly, because we now have other dyes of greater fastness that can be applied by easier methods. Cotton and linen fabrics which have been dyed with "salt" or "sulphur" colors are often improved by "topping" or redyeing with basic colors.

Insoluble tannates of antimony or some other metal are finally formed. Wool and silk because of their acid reaction are dyed with basic dyes in a neutral bath without previous treatment. Brighter colors fabrics are sometimes obtained from basic dyes.