PREPARING FOR DYEING

Scouring & mordanting

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.

Scouring

Removal of impurities

Scouring is the process of cleaning textile fibres 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. It improves dye uptake for more even colour, ensures brighter, cleaner shades, helps mordants penetrate the fibre better, and it prevents patchiness and uneven results.

✨ Before modern detergents, scouring relied on simple, natural materials that could break down oils and impurities. Wood ash mixed with water created an alkaline solution, often used to soak or simmer cloth. Fermented liquids, including aged urine, provided ammonia that helped cleanse and open the fibres.

Plants rich in natural soaps, such as soapwort, were used for gentler cleaning, especially on delicate materials. In some traditions, even animal dung was used for its enzymatic properties. Heat, time, and flowing water were essential, with textiles often boiled and rinsed repeatedly in rivers or streams.

These methods were slower and less controlled, but deeply effective, working with the nature of the fibre rather than against it.

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

Mordanting

Improving dye fixation

A mordant is a substance, usually a metal salt, that helps dye molecules bind to fibres. 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.

Good quality, natural fibres will always give the most beautiful and lasting results.

Follow safety guidelines when handling powders and hot liquids.

Method (alum)

  • Calculate the weight of fibre (WOF) when dry
  • Measure alum at 10–15% of WOF (so if your fibre 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 (plant) fibers, tannins are often used before or alongside alum to improve binding. Tannins are naturally occurring compounds found in many plants, such as bark, leaves, and galls, and play a key role in natural dyeing. They help fibres, especially plant-based ones, bind more effectively with dye, improving depth and longevity of colour. Common sources include oak galls, pomegranate rinds, and tannin extracts.

For protein fibres

Alum can be used alone. Cream of tartar is sometimes added (around 5–8% WOF) to improve softness and assist even uptake.

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