Dyeing Yarn with Turmeric — The Oldest Golden-Yellow Dye

For best colour fastness, mordant your wool with alum before dyeing. Follow the standard alum mordant recipe: 10% WOF alum, 6% WOF cream of tartar, simmer at 85°C for 45 minutes, cool overnight. If you want to demonstrate the difference a mordant makes, reserve a small unmordanted sample to dye alongside — the comparison is dramatic. If you are dyeing cotton or linen instead of wool, use alum acetate (aluminium acetate) as the mordant, since potassium alum bonds poorly to cellulose fibres.

Use 30-50% WOF of turmeric powder for a rich golden colour. For 100 g of wool, that is 30-50 g of ground turmeric. More turmeric gives a deeper, more orange tone; less gives a lighter lemon yellow. Use standard culinary turmeric powder — the same kind sold in any grocery store. Fresh turmeric rhizome can also be used: grate it finely and use about twice the weight of powder (60-100 g per 100 g wool) since the fresh root contains water.

Place the turmeric powder in a small bowl and add just enough warm water to make a smooth paste — about 100 ml. Stir until no dry clumps remain. This step prevents the powder from floating on the surface of the dye bath in clumps that stick to the yarn and cause uneven spots. The paste dissolves cleanly when added to the full volume of water. Turmeric stains everything it touches — hands, countertops, wooden spoons — so wear gloves and work on a protected surface.

Fill a stainless steel or enamel pot with about 4 litres of water per 100 g of wool. Add the turmeric paste and stir thoroughly until the water is an even bright yellow with no lumps. The dye bath should be the colour of strong curry broth. Use a dedicated dye pot — turmeric will permanently stain the inside of the pot yellow. Never use a reactive metal pot (aluminium, iron, copper) as these change the dye colour unpredictably.

If the mordanted wool has been stored dry, soak it in warm water for 20-30 minutes before adding to the dye bath. The fibres need to be fully hydrated so the dye penetrates evenly. Dry fibres repel the dye liquor and create light streaks. If the wool is still damp from mordanting, squeeze out the excess mordant bath and add it directly — no need to rinse between mordanting and dyeing. The residual alum on the fibre helps the dye bond.

Lower the damp wool into the turmeric dye bath while the water is still cool or lukewarm. Push it below the surface gently, spreading the skein so all parts contact the dye liquor. Adding wool to a cool bath and heating gradually ensures even colour uptake. Adding wool to an already-hot bath causes the outer fibres to grab dye immediately while the inner fibres stay pale — resulting in uneven, blotchy colour.

Place the pot on medium-low heat and bring the temperature up gradually — about 2°C per minute. Monitor with a thermometer. The dye uptake accelerates with heat: at room temperature, curcumin bonds slowly; at 70-85°C, the fibre absorbs dye rapidly. Do not let the bath boil — boiling agitates the wool and causes felting. It also degrades some of the curcumin, dulling the colour. A gentle simmer with small bubbles barely breaking the surface is the target.

Maintain the temperature between 80-90°C for 45 minutes. Every 10 minutes, gently lift and turn the wool with a wooden spoon — this ensures all surfaces contact fresh dye liquor. The dye bath will gradually become paler as curcumin transfers from the water into the wool. With 40% WOF turmeric, the bath will be nearly exhausted by the end — most of the colour is now in the fibre. The wool will look much darker wet than it will when dry.

After 45 minutes at temperature, turn off the heat. Leave the wool in the dye bath to cool naturally — at least 4 hours, overnight is ideal. Dye continues bonding during the slow cool-down. Removing wool from a hot bath into cool air risks felting from thermal shock. The longer the wool sits in the cooling bath, the deeper and more permanent the colour. Cover the pot with a lid to slow the cooling.

Lift the wool from the cooled bath and squeeze out the excess dye liquor (do not wring). Rinse in water that is the same temperature as the bath — start warm and gradually cool the rinse water over several changes. The first rinse will run deep yellow — this is excess surface dye washing off, not the mordanted dye releasing. Continue rinsing until the water runs mostly clear. Two to three rinses is usually enough for alum-mordanted wool.

Hang the rinsed skein on a drying rack or clothesline in shade. Direct sunlight fades turmeric-dyed fibre faster than almost any other natural dye — curcumin is photosensitive and UV light breaks it down. Indoor drying or shaded outdoor drying preserves the colour best. The yarn will dry to a bright, warm golden-yellow — lighter than it appeared when wet. Alum-mordanted turmeric on wool gives a colour reminiscent of marigold petals or saffron rice.

Turmeric is classified as a fugitive dye — meaning it fades with washing and light faster than dyes like indigo or madder. Even with mordanting, turmeric-dyed items should be washed gently in cool water and stored away from light. This makes turmeric best suited for decorative items, display pieces, and teaching samples rather than everyday garments. Its strength is accessibility: turmeric is available everywhere, works on every fibre type, needs no specialised equipment, and gives immediate, vivid results. It is the perfect gateway dye — the one that makes a beginner say 'I made that colour.'