Shop Towel Dyes
Shop towel dyes are made using a direct dye. Congo Red was the first direct dye developed in 1884 and proved to be the forerunner of a large class of synthetic dyes for dying cellulose. Direct dyes get their name from the process used for dying they are applied directly to cellulose without the use of any mordant. Mordants were needed prior to the discovery when trying to dye any cellulosic with virtually any natural colorant. Direct Dyes are water soluble and can be applied to cotton, rayon, linen, hemp, jute and ramie. Most direct dyes have limited wet fastness in medium to full shades unless they are after treated.
A Typical dye bath consists of dye, salt and an anionic wetting agent. Water acts as the application medium. The dye dissolves in water forming an ionized solution. The dye anions are fixed in the fiber by hydrogen bonding. Addition of the electrolyte (salt) is necessary for exhaustion of the dye since the cotton fibers take on a negative charge. The addition of the salt neutralizes the negative charge around the fiber and thus allows the direct dye anion to deposit on the surface of the fiber and diffuse into the fiber. Wetting agents may be added to facilitate better wetout of the fiber
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