How to Scour and Mordant Cotton and Linen

Scoured Linen Cotton Samples

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.

Scoured and Unscoured Dyed Linen Sample
Scoured and Unscoured Dyed Linen Sample

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.

Scour Linen and Cotton
Scour Linen and Cotton

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.

Where to purchase Aluminium Acetate (in UK)
Wild Colours
George Weil

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

Paivatar – Plant Dyed Wool Yarns

Look for some of my plant dyed yarns at my PaivatarYarn Shop on Etsy.

Plant Dyed Wool Yarn
Plant Dyed Wool Yarn

Natural Dye Books

Indigo from Seed to Dye

Indigo: Dye It, Make It: Techniques from plain and dip-dyeing to tie-dyeing and batik, in natural indigo blue

Wild Color, Revised and Updated Edition: The Complete Guide to Making and Using Natural Dyes

Natural Dyes

The Art and Craft of Natural Dyeing: Traditional Recipes for Modern Use

Dyes and Mordants on Ebay

Author: Paivi Suomi

I've had an interest in weaving, looms, yarns and textiles since I was a small child. I learned to knit, crochet, sew, do needlepoint at my mother's knee. My grandmother was a Saami from northern Norway. I am very interested in studying more about traditional Saami and Finnish style weaving and handicrafts. Paivi Suomi