Question

Some dyes cannot be applied directly, but must use a mordant to adhere to fabrics. Describe how this process differs from direct dyeing.

Answer 1

in the direct dyeing is normally carried out in a neutral or slight alkaline dyebath, at or near boiling point , but a separate aftertreatment such as cationic dye fixing , to enhance wet fastness has been necessary for most direct dyeing .
The term mordant is used for chemicals which usually have a metal with a valency of at least two or more, they can also be other types of compound as well.Natural dyes also referred as mordant dyes; do not readily adhere to cotton so mordants are used. Mordants are needed to set the color when using natural dyes.Different mordants will give different hue color with the same dye. A mordant is thus a chemical agent which allows a reaction to occur between the dye and the fabric. In textiles, mordants are used to fix the color in dyeing or fabric printing, especially for fabrics of plant origin (cotton)