Natural Dyeing (UK): Colouring Wool and Cloth with Plants

There is a particular satisfaction in lifting a skein of wool out of a pot of simmered onion skins and watching it deepen, in the air, to a warm gold you had no hand in mixing. Natural dyeing is old, generous and a little bit magic. The colours are soft and complex in a way bottled dye rarely is, they cost next to nothing, and they turn kitchen scraps and roadside weeds into something worth keeping. For a homestead it is the natural close to the fibre journey: you can raise or buy a fleece, learn to work with the wool, spin it into yarn, and then colour it with plants from your own garden and hedgerow.

It is also a craft with a bit of chemistry to respect. Nothing here is frightening, but you are handling mordants, so read the safety note first, keep a set of dye-only equipment, and never let a dye pot near your dinner.

Why fibre matters more than anything

Before you pick a single leaf, understand this one thing, because it decides whether you succeed: not all fibres take natural dye equally. Wool and silk are protein fibres, and their structure readily grips both mordant and dye, so you get strong, lasting colour with a simple preparation. Cotton, linen and other plant fibres are cellulose, and they resist natural dye; getting good colour on them needs extra steps, usually a tannin treatment as well as an aluminium mordant.

The practical lesson for a beginner is simple: start with wool or silk. You will get far better colour while you are still learning, and wool ties straight back to a homestead fleece. Leave cotton and linen until you have a few dye pots behind you.

The core method, step by step

Every plant dye follows the same basic sequence. Learn it once on a bit of undyed wool and onion skins, and you can apply it to almost anything.

How to dye wool with plants

1. 1

   Scour: wash the fibre truly clean

   Any grease, spinning oil or dirt stops the mordant and dye taking evenly, so start with a proper wash, called scouring. For knitting yarn or a silk scarf a gentle hand wash is often enough; a raw fleece needs a more thorough scour. Handle wet wool gently, because it felts if you agitate it or shock it with sudden temperature changes.

2. 2

   Mordant: fix the colour with alum

   The mordant is what bonds the dye to the fibre so the colour lasts. The word comes from the Latin for 'to bite'. For wool, dissolve alum at roughly 8 per cent of the fibre's dry weight (a little cream of tartar helps brighten and even out wool), stir into a pan of warm water, add the pre-soaked wet fibre, and heat gently. Leaving the fibre in the mordant bath for a good while, even overnight, helps it take up evenly. Then rinse off any loose mordant. Gloves and a dust mask on for this step.

3. 3

   Make the dye bath: simmer the plant material

   Cover your plant material with water in a dedicated stainless pot and simmer gently to draw the colour out, often for an hour or so, then leave it to steep. Many dyers strain out the plant matter before adding fibre so bits do not stick to it, though loose onion skins are forgiving. As a rough guide, use a similar weight of plant material to fibre, and more for a stronger colour.

4. 4

   Dye: add the fibre and heat gently

   Wet the mordanted fibre first, then lower it into the dye bath and bring it up to a gentle simmer. Do not let wool boil hard: keep it below a rolling boil (around 80 to 82 degrees C is plenty), because hard boiling and agitation felt wool into a solid mass. Hold it warm for around an hour, then turn off the heat and, ideally, let it cool in the bath. The longer it steeps, the deeper the shade.

5. 5

   Rinse and dry out of direct sun

   Lift the fibre out, let it cool slowly so the wool is not shocked, and rinse gently in water of a similar temperature until it runs clear. Squeeze, do not wring. Dry it out of direct sunlight, which fades fresh plant colour fastest of all, and let it rest before you judge the final shade.

UK dye plants and the colours they give

Half the pleasure is learning to read your garden and hedgerow as a palette. These are the reliable UK players. Forage responsibly, taking only a little and never from protected sites, and leave picked plants out in the open for a couple of hours so any insects can escape before they go in the pot.

Yellows are far and away the easiest and most common colour from foraged plants, which is why so many beginners end up with a drawer full of golds. Reaching for other colours is where mordants and modifiers come in.

Modifiers: shifting the colour you get

Once you have a dye taking, you can nudge the shade with a modifier, added to the dye bath or as a quick afterbath. Two are worth knowing from the start.

• Iron saddens and darkens colours. A pinch of iron (or dyeing in an old iron pot) turns yellows to olive and greens to grey, and greys down most shades. It is powerful, so use tiny amounts, and keep it in its own labelled jar well away from food.
• Acid or alkali shifts some dyes. Raising the pH with a spoonful of washing soda (alkaline) pushes some yellows greener and brighter; an acid such as cider vinegar shifts others the opposite way. Not every dye responds, so test on a sample.

Modifiers are the reason two dyers using the same nettles can pull very different colours from the pot. Keep notes: weight of plant, weight of fibre, mordant, any modifier, and the result. Your notebook quickly becomes more valuable than any recipe.

Colourfastness: be honest about fading

This is the part beginners most need to hear plainly. Some plant colours are gorgeous and some are fleeting, and the fleeting ones are called "fugitive". They fade, sometimes fast, sometimes even in a dark drawer, however carefully you dyed.

The usual culprits are the ones that look most tempting: blackberries and other soft berries, beetroot, red cabbage and turmeric all give glorious colour that does not last. Onion skins are gently fugitive too, though pleasantly so, softening from bright yellow to a muted paler yellow rather than vanishing. The genuinely lasting plant colours are the traditional dye plants: madder for red, weld for yellow, and woad or indigo for blue.

What you need: a simple starter kit

You do not need much, and a lot of it comes from a charity shop.

• Alum mordant (aluminium potassium sulphate or aluminium sulphate), and optionally a little cream of tartar for wool. Search: alum mordant for dyeing on Amazon.
• A dedicated stainless steel pot, big enough for the fibre to move freely, kept for dyeing only and never returned to the kitchen. Search: stainless steel stockpot on Amazon.
• Rubber gloves and a dust mask for handling mordant powder and hot dye. Search: rubber gloves and dust mask on Amazon.
• Plus dedicated spoons, a sieve and a jug, kitchen scales for weighing fibre and mordant, and a notebook. Onion skins, avocado stones and hedgerow plants are free.

Common mistakes

• Trying to dye cotton first. Start with wool or silk; cellulose fibres need extra preparation and disappoint beginners.
• Skipping the scour. Grease and oils block the dye and give patchy, streaky colour. Clean fibre first, always.
• Skipping the mordant (except for woad, indigo and a few tannin-rich plants). Without it, most plant colour washes or fades straight out.
• Boiling wool. A hard boil, or stirring and shocking wet wool, felts it into a lump. Keep it to a gentle simmer and handle it gently.
• Expecting a bottled-dye result. Natural colours are softer, more variable, and they shift over time. That is the point.
• Using kitchen equipment. The single rule not to bend: dye kit and food kit stay separate, for good.

Natural dyeing rewards patience and note-keeping more than any special talent. Start with a pot of onion skins on a handful of mordanted wool, get that right, and the whole hedgerow opens up. From there it sits happily alongside the rest of your fibre skills, from needle felting to spinning your own yarn, each one turning a raw fleece a little closer to something finished and your own.