Fabric and fibres

It is vital get to know the unique qualities of natural fabrics when natural dyeing. There are relationships between all the elements in this art form and centuries of discovery and practice all around the world has given us the keys to creating beautiful natural colour on cloth.

Botanical and insect dyestuffs will only work with natural fibres. There may be a few exceptions but generally these dyes will not work with synthetic fibres.

Natural fibres and fabrics fall under 2 categories that act differently in relation with natural dyes and mordants.

Protein fibres - made from animals

WOOL - SILK - CASHMERE - ALPACA - FUR -

Protein fibres are animal based products that are made from proteins. These fibres have a natural affinity with plant dyes and will form strong bonds with mordants and take up dyes readily when properly scoured and prepared.

The most common mordant used for protein fibres is Alum Sulphate to increase colour and lightfastness.

Key factors to keep in mind with protein fibres:

Protein fibres are sensitive to Ph:

• Prefer slightly acidic conditions (pH ~4–6)

• Avoid strong alkalis (like soda ash) — they can damage or dissolve protein (this differs to cellulose fibres)

Protein fibres can felt or weaken with:

• Rapid temperature changes

• Excess agitation

• High heat combined with movement

To avoid this:

• Gradually raise temperature

• Avoid stirring too vigorously

• Let cool slowly in the bath

Wool especially is prone to felting if shocked.

Iron must be used with caution with protein fibres as it may damage the fibre, so is best used in small quantities (1-2% WOF) as a mordant or modifier.

Cellulose fibres - made from plants

COTTON - LINEN - HEMP - RAMIE - BAMBOO - VISCOSE - RAYON - TENCEL - LYOCEL

Plant based fibres are made from cellulose and are structurally different from each other so are treated in different ways to get the best results and to maintain the integrity of the fibre.

Cellulose fibers lack the same structural affinity with the chemicals in natural dyes as protein fibers do, and require additional assistance to form a molecular structure that allows the dyes to bond.

Tannins and mineral salts of alum, iron and copper are frequently used to assist the cellulose and dye molecules to connect. See Mordanting Cellulose fibres

Cellulose fibres are much more resilient in alkaline conditions when scouring with soda ash or alkaline dye baths, and will also handle high temperatures.

Soy is also used to bind a protein to the cellulose fibre so the dye can attach to that and act more like a protein fibre. Soy milk is not a mordant in the mineral sense. It does not chemically bond dye to fibre like alum or iron. Instead, it works as a protein binder, helping pigment attach to cellulose fibres.

Dye results will vary according to many factors including quality of the fabric or fibres, how they have been manufactured and how they are prepared. Many natural dyes appear softer and less saturated than with protein fibres.

Both protein and cellulose fibres contain waxes, coatings, sizings and possibly dirt that needs to be removed to allow tannins, mordants and dyes to fix to the fabric. For best results all fibres require a thorough scour to prepare for the mordanting and dying process. See Scouring for more info.