Every kitchen produces them by the handful: the dry, papery outer layers of onions, peeled off and dropped into the bin without a second thought. For a small studio working with natural colour, those skins are one of the most generous and forgiving dyestuffs available. They cost nothing, need no special sourcing, and yield warm golds, ambers and soft ochres that sit beautifully on wool, silk and other protein fibres.
The colour comes largely from quercetin, a flavonoid that bonds readily with mordanted fibre. Brown and yellow onion skins give the classic golden amber; red onion skins lean towards a softer, slightly pinkish bronze. If you are hand sewing a waistcoat, a linen sampler or a small run of wool cushions, onion skins are an ideal starting point because they behave predictably and the results feel thoroughly domestic.
Start a dedicated paper bag or open jar in a dry corner of the kitchen and add skins as you cook. Keep them away from damp — mouldy skins smell dreadful and can spoil a dye bath.
Aim to gather roughly the same weight of skins as the dry weight of fibre you intend to dye. For 100g of wool fabric, 100g of skins gives a solid golden shade; 150-200g pushes it towards a rich, glowing amber. Keep the used skins after your first bath — they will often give a second, paler exhaust dye that is lovely for overdyeing or contrast panels.
Onion skins alone will stain fibre, but the colour will wash away quickly unless the cloth is mordanted first. For protein fibres such as wool and silk, an alum mordant is straightforward and safe for a small studio.
Cellulose fibres such as cotton and linen need more help. Treat them with a tannin first — oak gall, sumac or even a strong tea — then mordant, or accept a lighter, more washed-out result. Always use stainless steel or enamel pans; aluminium and iron pans will alter your colours unpredictably.
Cover your skins with plenty of water — at least four times their weight — and leave them to soak for an hour or two. This softens the papery layers and helps the colour release evenly.
Bring the pot slowly to a gentle simmer, around 80-90°C, and hold it there for 45-60 minutes. A rolling boil is unnecessary and can dull the brightness of the gold. Once the liquid is a deep, translucent amber, strain it carefully through a sieve lined with muslin or an old clean stocking. Strain well: stray fragments of skin will stick to wool like confetti and are tiresome to pick off a finished piece.
You can dye in the same pot with the skins still in, tied loosely in a muslin bag, but straining first gives cleaner, more even results, which matters when you are hand sewing a garment you hope to keep for years.
Add your pre-mordanted, thoroughly wetted fibre to the strained, lukewarm dye bath. Bring the temperature up slowly over 30-40 minutes, then hold at 80-90°C for 45-90 minutes. Stir gently and infrequently — agitation plus heat is what felts wool, and a felted length of hand-woven cloth is a heartbreaking thing to salvage.
When the colour looks a shade deeper than you want, turn off the heat and let the fibre cool in the bath, ideally overnight. Wool takes up colour as it cools, and the slow finish gives a more level, luminous result. Rinse in water of the same temperature, then in gradually cooler water, until the run-off is clear.
The same bath can produce a whole family of colours with a little patience and a few test scraps.
Always test on small squares of mordanted cloth before committing a whole piece, and keep the modifier baths separate from your dye pots.
Natural colour is a living thing, and onion-skin golds are moderately lightfast rather than permanent. Keep a simple notebook: fibre weight, skin weight, mordant percentages, temperatures, timings, pH tweaks and the resulting shade. Tape a small dyed snippet beside each entry.
Store finished pieces out of direct sunlight and wash them rarely, in cool water with a pH-neutral soap, pressing rather than wringing. If you are hand sewing with naturally dyed cloth, remember the thread will age differently from the fabric — choose a colour you will still love when it fades. That gentle shifting is part of the charm of slow textiles, and onion skins, gathered quietly from the kitchen, are one of the kindest ways to begin.
The Indigo Garret shares practical, down-to-earth guidance on natural dyeing, hand sewing and slow textile crafts for small studios for readers across the UK.
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