Tuesday, January 14, 2014

Let’s learn about the colorants used in the textile industry

Dyes are the coloring agents or chemicals that are used to give different color shades to a fabric. The color of a fabric is what makes it more appealing and different from all others.

To color a fabric, the coloring agents are mixed in an aqueous solution. To improve the color fastness of the fiber, dyers add mordant to this solution. In other words, the addition of mordant helps to increase the strength of the coloring agent, which adheres to the fabric.

Once the solution is prepared, the fabric is dipped in it, in order to bring attractive color shades. When a fabric is dipped into the mordant mixed aqueous solution, the colorant adheres to the fabric.

In the next section, we will take a quick look at the different types of coloring agents, which are most commonly used in the fabric industry.

     Vat Colorants:
Vat dye comes in the category of dyes in which colors are obtained through oxidations. They give bright and strong color shades to the fabric after dying. These dyes are used to color different types of fabrics such as; cotton, wool etc. Colors through vat dyes are obtained by dipping the fabric into the aqueous solution.

     Mordant colorants:

The dyes that come under this category require a mordant to produce the desired color shade. The unique feature of such colorants is that it attaches to the fabric strongly, to produce color fastness properties. In other words, the fabric that is dyed using mordant colorants keeps its color even after several washes. Most common types of mordant dyes include: tannic acid, chrome alum, sodium chloride, alum etc.
     Acid colorants:
These types of coloring agents are soluble in water. When used for coloring, the chemical bonding between the colorant and the textile is obtained through the formation of acidic salts. These dyes are widely used in the textile and medical industry.

     Base colorants:
Base colorants are used to color fabrics of various types such as silk, wool, acrylic etc. Base dyes are also used to color paper.

     Sulfur colorants:
These coloring agents are mainly used to color cotton fabrics and produce dark shades. The Dyeing process of dyeing through sulfur dyes generally is done in two steps:

In the first step; the fabric is turned to pale yellow and in the second step; the dark color of the fabric is obtained by adding a sulfur compound.