Preparation steps for natural dyeing
Natural dyes bind best to fibres that are clean and properly prepared. Two key steps are used to achieve this: scouring and mordanting. These processes remove unwanted residues and create the conditions needed for dye to attach to the fibre in a stable way.
Removal of impurities
Scouring is the process of cleaning textile fibers to remove oils, waxes, dirt, and manufacturing residues. Even new fabrics often contain sizing agents or finishes that prevent water and dye from penetrating evenly.
If scouring is skipped or insufficient, dye uptake will be uneven and colorfastness will be reduced.
Method
For plant fibres (cotton, linen, hemp, nettle, etc.):
– Fill a non-reactive pot with enough water for the fabric to move freely
– Add soda ash (sodium carbonate) at approximately 2–5% of the fabric’s dry weight, or use a strong natural detergent
– Add the dry fabric and bring to a gentle simmer (around 80–90°C)
– Maintain heat for 60–90 minutes, stirring occasionally
– Rinse thoroughly until water runs clear
For protein fibres (wool, silk):
– Use warm water (below 60°C) to avoid damage
– Add a mild, pH-neutral soap
– Submerge the fabric and hold temperature steady for 30–60 minutes
– Avoid agitation to prevent felting (wool)
– Rinse gently at similar temperature
Improving dye fixation
A mordant is a substance, usually a metal salt, that helps dye molecules bind to fibers. It forms a bridge between the fibre and the dye, improving colourfastness to washing and light.
Different mordants can also influence the final colour. Alum (potassium aluminium sulfate) is the most commonly used mordant for natural dyeing due to its relative safety and reliability.
Method (alum mordant)
– Calculate the weight of fibre (WOF) when dry
– Measure alum at 10–15% of WOF (so if your fiber weighs 100 grams, you'll use 10-15 grams of alum)
– Dissolve alum fully in hot water before adding to the pot
– Fill a non-reactive pot with warm water and add the dissolved mordant
– Add clean, wet fabric
– Heat slowly to around 80°C and hold for 45–60 minutes
– Allow fabric to cool in the bath for several hours or overnight
– Remove and rinse lightly, or use directly depending on dye process
Optional additions
For cellulose fibers, tannins are often used before or alongside alum to improve binding. Common sources include gallnuts, oak galls, or tannin extracts.
For protein fibers, alum can be used alone. Cream of tartar is sometimes added (around 5–8% WOF) to improve softness and assist even uptake.
• Always use non-reactive vessels (stainless steel or enamel)
• Ensure even submersion to avoid patchy results
• Label equipment used for dyeing and do not reuse for food
• Dispose of mordant baths responsibly
