What is mordanting, an art where colours bond to the fabric naturally?

Mordanting is the process of binding natural dyes to the fibres of textile materials. Mordant is derived from the French word mordre, which means 'to bite,' since it helps in binding and fixing the dye colour into the fibre of the material. Most natural dyes will not last on material without the appropriate mordant.

Mordanting creates a chemical bridge between dye and fibre

The role of a mordant is to act as a link between the dye molecules and the fibre molecule. Most common mordants include metallic salts, which consist of metal ions combined with a non-metallic substance. The metal ions have a tendency to form coordination complexes not only with the dye molecule but also with the fibre molecule, forming fibre-mordant-dye.

The process is far more complicated than using chemical dyes. The mordant used, its strength, the temperature, time taken, the acidity of the water, and the treatment of the fabric itself can alter the result. In fact, two dyers working with the same dye, the same mordant, and the same fabric may end up with entirely different colours due to small variations in technique.

In natural dyeing, the art of mordanting has three major functions. Mordants assist dyes in adhering to the fibre, affect the colour that is formed, and enhance the colour fastness of the fabric under specific combinations of dyes and fibres. The selection of mordants is determined by the fibre and natural dye used.

Plant-based mordanting can also be used. Rhubarb, chestnuts, oak galls, and sumac are sources of tannin that can be useful when preparing cellulose fibres. These plants may even offer colour of their own, forming rich bases. The oak galls have been especially identified as tannin sources for cellulose fibres.

The metallic mineral salt mordants are alum, iron, copper, chrome, and tin. Alum gives a brighter colour, whereas iron is used to darken the dyes, giving them grey tones. There is no standard effect; it depends on the type of dye and fibre used. In some cases, a substance can act as a dye and mordant at the same time.

Since various mordants have varied responses when applied to different types of fabrics with different dyes, selecting one becomes very perplexing. Some of them require some extra work or additives, while others are easy to use. The best way to select a mordant is by knowing your fabric and dye well.

For more updates, join/follow our WhatsApp, Telegram and YouTube channels.