Making Natural Dyes from Kitchen Scraps

Why kitchen scraps are worth dyeing with

There is something quietly satisfying about pulling a pan of onion skins off the hob and watching it turn the colour of October sunlight. Natural dyeing has a reputation for being fiddly, expensive and slightly mystical, but most of what you need is already in your compost bin. Onion skins, beetroot peelings and avocado stones give a surprising range of shades, and they cost nothing at all.

The colours tend to be softer than synthetic dyes — earthy golds, dusty pinks and muted greens rather than neon brights. They also shift depending on the fibre, the water in your area and whether you add a mordant. That unpredictability is half the pleasure. Treat your first few batches as experiments, keep notes on what you did, and you will quickly build a small palette of favourites. Wool, silk and other protein fibres take up these dyes most readily, though plant fibres such as cotton and linen will work beautifully if you mordant them properly first.

Setting up: pots, mordants and preparation

Before you start, earmark a stainless steel or enamelled pan for dyeing only. Aluminium pans can dull your colours and cast unwanted greys, and anything you use for dye should not go back to cooking with afterwards.

A mordant is what helps the dye bond to the fabric so it does not wash straight out. Two reliable options are alum (potassium aluminium sulphate) and cream of tartar. A good general recipe for wool or silk is roughly 10 per cent alum and 5 per cent cream of tartar by the dry weight of your fabric — so 10g of alum and 5g of cream of tartar for 100g of wool. Dissolve them in warm water, add your pre-wetted fabric, and hold it at a gentle simmer for about an hour without boiling. Let it cool in the liquid, then rinse.

• Weigh your fabric dry before you wet it, and write the figure down.
• Scour new fabric first — a hot wash with a little soda crystals removes the factory finishes that block dye.
• Soak plant fibres in soy milk overnight and dry them before mordanting; the protein helps cotton and linen grab colour.
• Keep a rusty nail in vinegar to add to a dye bath for greys, olives and deep greens — this is called modifying, and a little goes a long way.

Onion skins: the reliable gold

Brown onion skins are the most forgiving dye material you will ever use. Collect them in a paper bag in the kitchen until you have two or three generous handfuls, roughly 30g for a 4-litre bath. Simmer the skins in water for 30 to 45 minutes, then strain them out and compost the lot.

Add your mordanted, wetted fabric and simmer gently for an hour. Wool and silk will come out a warm amber that deepens to a coppery bronze if you leave it steeping overnight. Cotton takes a paler honey tone. Red onion skins behave differently and can give soft pinks to greens depending on the mordant, while a splash of iron water will swing the whole bath towards a rich, mossy brown.

Beetroot: vivid, but short-lived

Beetroot produces a spectacular magenta that is, unfortunately, the least lightfast colour in the kitchen dyer's repertoire. The pigment breaks down with heat, light and washing, so it is best kept for paper, gift wrap, bunting and decorative pieces rather than anything you intend to wear weekly.

Chop peelings or a tired cooked beetroot, simmer gently for 45 minutes, and strain. Keep the temperature low — a rolling boil destroys the colour. Beetroot dye is pH sensitive: a glug of white vinegar pushes it towards clear pink, while a pinch of bicarbonate of soda takes it to a deeper plum or a soft brown. Rinse in cool water, dry in the shade, and enjoy it while it lasts.

Avocado stones: the surprise pink

Here is the one that converts sceptics. Avocado stones, and the papery brown skins around them, give a beautiful blush pink to peach on mordanted fabric. Fresh stones work best, so freeze them as you use them and dye when you have a bagful.

Chop the stones roughly — a heavy knife and a steady hand are needed — and simmer them for an hour or more until the water turns a rusty pink. Strain, add mordanted fabric, and hold at a low simmer for another hour. Wool and silk take a rosewood pink; cotton gives a paler, tea-rose shade. Adding a little iron water after dyeing will turn it a smoky grey-lilac, which is lovely on linen.

Fixing, storing and using your dyes

Once dyed, rinse your fabric in water of gradually cooler temperatures until it runs clear, then wash it gently in a pH-neutral soap and dry it out of direct sunlight. Colours will always soften slightly on that first wash, so aim a shade darker than you want.

• Store leftover dye baths in labelled jars in the fridge for a week or freeze them in bottles.
• Dip paper for cards, bookbinding and lampshades — a shallow tray of onion-skin dye gives beautiful aged edges.
• Label everything with the date, material and mordant used, so you can repeat the winners.
• Keep a swatch book of small fabric squares; it becomes a reference you will reach for again and again.

Start with onion skins, keep your notes, and let the avocado stones be your next small adventure. The colours you coax from a Monday night's cooking are genuinely your own, and no two batches will ever be quite the same.