Natural dyeing

The craft is getting colour out of a plant, mineral or insect and into a fibre so that it stays there. That last clause is the whole discipline. Almost anything will stain cloth once; making a colour that survives washing and light is a chemical process with three separate stages, and the reason so much of the published material disappoints is that it describes the third and skips the first two.

The three stages are scouring, mordanting and dyeing. Scouring removes the oils, waxes and finishes on the fibre, which otherwise sit between the dye and the material. Mordanting deposits a metal salt — usually aluminium — onto the fibre, which the dye molecule then bonds to. Dyeing is the part everybody photographs. Skip the first and the colour is patchy; skip the second and, for most dyes, it washes out.

A distinction worth having early: substantive dyes need no mordant because they bond to the fibre themselves, and indigo is not really a dye at all in the usual sense — it is insoluble, has to be chemically reduced into a soluble form, and develops its colour in the air after the cloth comes out. Those exceptions are why a beginner following one recipe finds that the next one contradicts it.

What actually decides the colour

Fibre first, mordant second, dye thirdThe same dye bath gives quite different colours on wool and on cotton.

The stage people skip

ScouringAnd then blame the dye for the patchiness.

Cheapest real result

Onion skins on wool, for nothing

The rule with no exceptions

Dye equipment never returns to food use

A first project that will actually work:

1. 1

   Step 1: Start with wool, not cotton

   A 100g skein of undyed wool. Protein fibre takes a simple alum mordant and gives an unambiguous result, which is what you need in order to learn anything from the attempt.

   You will know it worked when: The variables are down to two rather than five.

2. 2

   Step 2: Scour it properly

   Simmer gently in water with a little pH-neutral detergent, rinse thoroughly. Skipping this is the single commonest cause of blotchy dyeing and it is invisible until the end.

   You will know it worked when: The fibre wets out evenly instead of repelling water in patches.

3. 3

   Step 3: Mordant with alum, by weight

   Weigh the dry fibre; weigh the alum as a percentage of it — this is why the scale matters more than anything else you will buy. Simmer, then let it cool in the bath overnight.

   You will know it worked when: The fibre is chemically prepared to bond with the dye.

4. 4

   Step 4: Make the dye bath from onion skins

   A carrier bag of skins from the greengrocer, simmered for an hour and strained. Free, forgiving, and it produces a colour nobody believes came from onions.

   You will know it worked when: A working dye bath at no cost.

5. 5

   Step 5: Dye slowly and let it cool in the pot

   Bring the fibre up to temperature gradually, hold it below a rolling boil, and then leave it. Most of the colour goes in during the cooling, and rushing this stage is what produces pale results.

   You will know it worked when: Even, deep colour rather than a patchy tint.

6. 6

   Step 6: Keep a sample and a written record

   A tag with fibre, weight, mordant percentage, dye, quantity and time. Six months later this is the difference between a craft and a series of accidents.

   You will know it worked when: You can repeat the good ones.

Fibres divide into protein and cellulose, and they behave so differently that a recipe written for one is close to useless for the other. Protein fibres — wool, silk, alpaca — carry the amino groups that most natural dyes bond to readily, take a simple alum mordant well and generally give deeper colour. Cellulose fibres — cotton, linen, hemp — are chemically far less receptive and need a longer, more involved mordanting process, traditionally involving tannin as well as alum. A beginner who starts on cotton because it is cheap will conclude the craft does not work.

Water is the variable nobody mentions and it changes results measurably. Hard water carries calcium that shifts some colours and dulls others; iron in the supply will sadden every colour in the pot, which is sometimes exactly what you want and never what you expected. If your results do not match a recipe from elsewhere, the water is a likelier explanation than anything you did.

That last row deserves its own sentence, because it is the commonest disappointment in the craft. A great many strongly coloured plants make dyes that are not lightfast: the beetroot scarf is spectacular for a month and pink-grey by the following summer. Nothing is wrong with using them, and quite a lot of the appeal of the craft is that colour is not permanent — but the material that promises a permanent beetroot red is selling something.

The techniques that produce most of the range in a dyer’s work:

• Modifiers — A dip in an iron or alkaline solution after dyeing shifts the colour, often dramatically. Iron saddens and darkens; alkali swings some yellows to gold and some reds to purple. One dye bath can give four colours this way.
• Exhaust baths — A used dye bath still holds colour. A second and third batch through it give progressively paler shades of the same hue, which is how a coherent gradient is made rather than by mixing.
• Solar dyeing — Fibre, plant matter and water in a sealed jar on a windowsill for weeks. Slow, unpredictable and needs no heat at all — the best method for anybody without a workspace.
• Bundle dyeing and eco printing — Plants laid on damp cloth, rolled tight and steamed, printing their own shapes. Visually the most striking thing the craft does and among the least controllable.
• Overdyeing — Dyeing an already-dyed cloth in a second bath. Yellow over blue makes green; it is also how a disappointing result gets rescued rather than discarded.
• Resist — Binding, folding, stitching or clamping the cloth so the dye cannot reach parts of it. An entire family of traditions in its own right.

Everything above is worked as a percentage of the dry weight of the fibre rather than as a volume of water, and that is the single most useful thing to internalise. Fifty per cent madder on wool means fifty grams of madder to a hundred grams of wool, and the amount of water only needs to be enough for the fibre to move freely. Recipes given in cups and pans do not scale and cannot be repeated; recipes given as percentages do both.

Everything genuinely needed, and nothing that is not:

• A stainless steel pot, dedicated — Five litres or more. Stainless is neutral; aluminium and cast iron both react with the bath and change the colour, which is occasionally useful and usually a surprise. This pot never cooks food again.
• A scale accurate to a gram — The most important purchase after the pot, because everything in the craft is a percentage of fibre weight. A kitchen scale that rounds to five grams is not good enough for mordanting a hundred-gram skein.
• A second pot, eventually — So mordanting and dyeing can run at the same time. This is the purchase that halves the elapsed time of every project.
• Long tongs or a dowel — For lifting hot wet fibre out of a bath without wringing or agitating it. A wooden dowel is fine and costs nothing.
• Gloves, a mask and a sieve — Nitrile gloves for mordants, a dust mask for weighing powders, and a sieve or muslin for straining plant matter out of the bath.
• Jars, if you have no space — Solar dyeing needs a windowsill and a lidded jar. No pot, no heat, no ventilation problem — and weeks instead of hours.
• A notebook — Not sentimental. Fibre, weight, mordant percentage, dye quantity, water, time and a stapled sample. This is what turns results into knowledge.

The other hazards, which are more mundane and more likely:

• Hot liquid, in quantity — Five litres of near-boiling dye bath is the real injury risk in this craft. Work at a height you can lift from, and never carry a full pot across a room.
• Plants you have not identified — Some excellent dye plants are seriously toxic, and a few look like edible ones. Identify positively before gathering, and keep dye plants away from anywhere food is prepared.
• Fine powders — Weighing dried madder or cochineal releases dust. A mask and a still room, or do it outdoors.
• Indigo vats — The chemical reduction methods use materials that need their own reading. The fermentation methods are gentler and slower and are the better place to start.
• Disposal — Spent plant dye baths are generally fine down a drain. Mordant baths are not obviously so, and the honest answer is that it depends on the mordant and on your water authority — check rather than assume.

• Mordant dyeing — The mainstream: fibre prepared with a metal salt so the dye bonds durably, then dyed. Almost everything with reliable lightfastness goes through this route, and the mordanting stage is where the safety section applies rather than the dyeing.
• Vat dyeing and indigo — Chemically distinct from everything else here — indigo is insoluble and has to be reduced in a vat, then oxidises on the fibre in air. No mordant, a living or chemically maintained vat, and the colour appearing as it meets the air is the moment that converts people.
• Bundle dyeing and eco printing — Plant material rolled against fabric and steamed, printing shape as well as colour. Immediate, needs almost no equipment, and unusually unrepeatable — which is either the appeal or the objection.
• Resist and pattern methods — Shibori, clamp, wax and paste resists, where the pattern is made by what the dye cannot reach. Combines with any of the dye methods above and has deep traditions of its own in several cultures.
• Lichen and fungal dyes — A small specialism with striking results, some of it needing months of fermentation. Lichens raise a collection ethic that plant dyeing does not — many grow at a few millimetres a year — and the societies that own that question are the right place for it.
• Kitchen and food-waste dyes — Onion skins, avocado stones, black beans, tea. The cheapest possible start and genuinely instructive, but this is where fugitive colour lives: several of these fade markedly and it is worth knowing that before dyeing something you care about.
• Contact with the wool and cloth crafts — Most dyeing exists to feed something else. Knitting, embroidery and dressmaking all have their own pages here, and the dye calculator on this site is written for weighing against fibre weight rather than against volume.

The current revival is driven by three groups who overlap less than they appear to: historical reconstructors interested in what was actually done, textile artists interested in the colours, and people looking for a lower-impact alternative to industrial dyeing. They want different things from the same craft, which is why advice from one camp often reads oddly to another.

That third motivation is where care is needed. "Natural" is not a synonym for "harmless" — some historical mordants are genuinely toxic, the water use is substantial, and a fair comparison against modern industrial dyeing would need a proper assessment that we have not done and are not going to summarise from other people’s summaries. What can be said plainly is that alum on wool at kitchen scale is a mild process, that chrome and tin belong in the history books rather than in a hobby workshop, and that anybody claiming a definitive environmental verdict either way is going beyond what we have seen established.

The community itself is generous and unusually well documented for a craft this size, largely because the modern revival grew up alongside the internet and its practitioners have been publishing their results in public from the start. The convention of recording fibre, mordant percentage and water alongside a photograph is what makes that body of work usable, and adopting it is the most useful cultural habit a beginner can pick up.