What is Mordant?
A mordant is a chemical binding agent that adheres well to both the fibers and the dye. A mordant is a substance used to set dyes on fabrics by forming a coordination complex with the dye which then attaches to the fabric. A mordant is always a polyvalent metal ion. The resulting coordination complex of dye and ion is colloidal and can be either acidic alkaline. Mordants can be added before, during or after the dyeing process. Most recipes use mordanting before dyeing. The type of mordant used can change the color of both the dye-plus-mordant solution and influence the shade of the final product.
Mordanting the fibre is perhaps the most important step in successful dyeing. It is often rushed or even omitted because no visible change occurs. Mordants facilitate the bonding of the dyestuff to the fibre.There are many mordants and each one will encourage a different shade from a particular dyestuff.
Alum is the mordant most frequently used by dyers for protein (animal) and cellulose (plant) fibres and fabrics. It improves light and washfastness of all natural dyes and keeps colours clear. It is inexpensive and safe to use. This form of alum is refined from bauxite, the raw state of aluminum ore, and is free from the impurities (such as iron) some other alums can contain.
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