Natural Dyeing


Natural dyes‘ is the term used to describe the colours that occur in nature and can be extracted from plants, trees, roots, lichens, fungi, molluscs and some insects. Around 160 years ago, before the discovery of modern laboratory dyes, all fabrics and textile products were printed and dyed using dyes from nature.  This workshop will show you how to dye fabric or yarn using onion skins. The onion skins are abundant in large supermarkets. If you ask politely, most will allow you to collect them.

Nearly all natural dye recipes in books and online will require the addition of a ‘mordant’ during the dyeing process. Mordants are metal salts which help to fix the colour pigment to the fibre being dyed. Although it’s possible to dye fabric without mordants, the colours may fade quicker or results not be as strong. There are 4 mordants you can use for natural dyeing,

  1. Alum, (aluminium sulphate)
  2. Copper, (copper sulphate)
  3. Tin, (stannous chloride)
  4. Chrome, (potassium bi-chromate)

The most common mordant used is alum, this is non toxic and easy to find in the form of ‘crystal’ or ‘rock’ deodorant or online from crafts suppliers, which are listed in the resources section at the end. Chrome is rarely used nowadays due to concerns about it’s environmental impact. Copper mordant can be made at home by saving copper items in water then using the water or by scrubbing the inside of a copper pan or vessel vigorously with a wire scrubber before using it to heat dye or soaking water. The recipe and method for dyeing wool or silk with onion skins is below.


Dyestuff -100g dry onion skins from red or yellow onions

Fibre – 100g wool or silk yarn or fabric (must be 100% pure)*

Mordant – 8g crystal deodorant rock crushed up (alum)

Assistor – 5ml lemon juice (citric acid)

Eco washing up liquid (PH neutral)

Water for mordant bath & dye-bath

* natural dyes work best on natural fibres, especially wool & silk


Rubber gloves and apron

Plastic bucket

Weighing scales

Small plastic tub for weighing alum*

Large old pan*

Wooden spoon or stirrer*

5ml teaspoon*

Colander or sieve

Gas or electric heating ring/hob

*please do not use for food preparation afterwards

*always wear gloves, goggles and protective clothing when handling chemicals and do dyeing in a well ventilated space.


Weigh your dry yarn, fabric or fibre and make a note of the weight. This number is now your 100% number for all of your calculations. (For example if your fabric or yarn weighs 50 grammes then 50g is your 100%. If it weighs 72 grammes then 72g is your 100% weight) etc.

Depending on the dry weight of your fabric or yarn, weigh out 100% weight dry onion skins. This is your ‘dyestuff‘.

Now weigh out 10% of alum. This is your ‘mordant‘.

In a large pan soak your yarn or fibre in some hot simmering water and a tablespoon of eco-washing up liquid for 30 minutes. Try not to boil as this damages the fibres. This is known as ‘scouring‘.

Rinse every trace of soap from the scoured fabric in lukewarm water 3 times at least. don’t use cold water as it will ‘shock’ the fibres.

Make your ‘mordant’ bath. Place your crushed alum in the clean large pan with plenty of simmering water, stir until dissolved then add your scoured fabric or yarn and simmer for 30 – 45 minutes.

Move or ‘agitate’ your fabric or yarn gently and regularly in the mordant bath to ensure even absorption of the alum into the fibres and avoid ‘patchy’ dyeing. Be careful with wool so as not to felt it. Afterwards you can leave the fabric/yarn to soak in the cooled mordant overnight if you wish, it can help make stronger shades. Make sure it is fully submerged.

Make your ‘dye-bath‘. Place the dry onion skins into the clean large pan with plenty of simmering water and stir thoroughly. Simmer for 30 – 60 minutes then strain the dye liquid from the onion skins making sure to keep the liquid! Dispose of the onion skins or re-use for a paler dye-bath.

Rinse your mordanted fabric/yarn a little under some running lukewarm water to remove any unattached alum crystals then squeeze excess rinse water out.

Add mordanted and rinsed fabric/yarn to the simmering dye-bath and cook for 30 – 60 minutes, agitating gently and regularly.

Rinse the dyed fabric/yarn with lukewarm water and a little eco soap to remove excess dye. Dry and enjoy your beautiful naturally dyed materials!

A range of natural fibres & materials dyed with onion skins and no mordant

  1. natural wool fleece, 2. soy bean yarn, 3. plain cotton, 4. calico, 5. white linen, 6. natural unbleached linen, 7. habotai silk, 8. silk noil, 9. bamboo & silk mix, 10. wool flannel.

Useful links/suppliers/books

george weil – mordants, dyestuffs, materials:

wild colours – mordants, dyestuffs, materials:

natural dye: Experiments and results:

jenny dean’s wild colour: