How to Scour Cotton & Linen

By Paivi Suomi on September 14, 2017

The secret to successful natural dyeing of cellulose fibres, yarns and fabrics such as cotton and linen is thorough scouring. The scouring process removes natural oils, waxes and pectins from the fibre so that the dyes can penetrate the fibre more readily.

Scouring and mordanting cellulose fibres is a more time consuming process than when mordanting wool and protein fibres. But it is well worth taking the extra time to prepare your fabric before you put it into the dyepot.

Here is a sample of natural brown linen fabric that has been dyed with Madder Root. One has been scoured prior to Aluminium Acetate mordant and Madder dye, and one hasn’t.

How to Scour Linen and Cotton
Weigh out the fabric or yarn you wish to scour.
For 100 grams of fabric I use:
10 grams Soda Ash
3 grams Carbolic Soap
Add this to water and mix.
Add the yarn or fabric.

Bring to a boil and let it simmer +2 to 3 hours.
The water will become brown as the waxes and oils are released from the fabric.
Even a bleached white linen will give you water that looks murky.
Let the fabric cool and then remove it from the scouring soak.
Rinse the fabric thoroughly.

As the Soda Ash has a high pH, the fabric needs to be soaked in an acidic vinegar solution to return the pH back to neutral. Plant dyes are sensitive to different pH levels and this can affect the final colour, so changes in pH during the mordanting process must be neutralized before dyeing the fabric.

Mordant for Cotton and Linen
To mordant cellulose fibres I use Aluminium Acetate
To mordant 100 grams of fabric,
Mix 5 grams aluminium acetate into a bowl or plastic bucket of hot tap water.
Stir until dissolved.

Add the scoured and rinsed fabric or yarn.
Let this soak for + 1 hour.
The yarn or fabric can then be removed from the mordant solution and allowed to dry, or it is ready to use as is.

More about Plant Dyed Yarns
Madder Root Dye Recipe
Brazilwood Dye Recipe
Eucalyptus Leaf Dye
Himalayan Rhubarb Dye