Natural dyes tend to fall into one of three types, mineral, substantive or adjective. The type of natural dye will determine if a mordant needs to be used.
There are many adjective natural dyes which only give a worthwhile colour and a good level of wash and light fastness if the fibres are prepared with a mordant. There are a host of materials which, used in the correct way will dye fibres and textiles. Many of these are found in the wild, in the kitchen or can be cultivated in the garden. To these can be added a further range of imported materials grown in hotter or damper climates. The great majority of dyes only give a relatively permanent colour if the fibres are mordanted.
Using Adjective Natural Dyes
In general, to give a strong colour, use an equal weight of plant material to the dry weight of the fibre, yarn or fabric. However when dyeing with heart-woods, dye extracts or cochineal, much smaller quantities, around one tenth of the dry fibre weight, are needed for a strong colour.
Mordanted wool, silk, cotton or linen can be dyed with many flowers, leaves, roots, fruit as well as heart woods and some scale insects. The only 'impossible' colour is a good blue, and with that a clear green, made from clear blue and clear yellow. Both of these depend on indigo.
Natural dyeing has much in common with cooking. No two batches turn out exactly the same. There are many very different recipes. Each recipe intended to create the same outcome, and each dyer considers their recipe to be superior. We thoroughly recommend that you record dyeing information and keep swatches of the results!
To create a colour, pre-soak the natural dyestuff (placed in a muslin bag to avoid it getting mixed with the material), then bring the mordanted fibre, fabric or yarn and the dyestuff to the boil (except madder which should be kept below 50°C) in the same dye bath. Hold at a simmer for one hour and allow to cool slowly. Wash in cool water until it runs clear.
The substantive natural dyes do not need a mordant to colour the fibre. These include the tannic acid from gall nuts, walnut leaves, turmeric, as well as alizarin reds from annatto, cochineal (pictured) and safflower, indigo and the purple of some molluscs. The use of a mordant enhances and can modify these colours.
Mineral dyes are produced by the metallic ions in the mordant salts. This gives a yellow from chrome, brown from the iron salts and blue from copper.
Sensible precautions should be taken when handling dyes and chemicals, particularly as powders:
- Avoid inhaling dusts, they can produce an asthma type reaction. People with known respiratory problems should not handle synthetic dyes, and particularly the fibre reactive dyes, in powder form. A dust mask should be worn when working with the powders or exposed to an aerosol from spraying dye solutions made up in water.
- Avoid splashing solutions into the eyes, swallowing the materials or prolonged skin contact. A simple 'non-contact' approach (most people use gloves to avoid dyeing themselves) plus normal, good, hygiene is sufficient precautions for the occasional user
- Store in clearly labelled containers well away from children, pets and foodstuffs. Treat dye powders and solutions with the same caution as domestic poisons (e.g. strong cleaners, bleaches or medicines)
- Dispose of spent solutions containing residues of the dyes responsibly. Dilute and pour onto waste land or into the sewage system. They have no known effect on the environment when used in the quantities recommended in the literature