Turmeric produces a bright yellow/orange colour that can be combined with woad, cochineal or safflower to give a wide range of colours. Adding acids and alkaloids at different stages of the dye process also changes the hue of the final colour. In an alkali solution it will turn red (baking soda) but if acid is added to neutralise the alkali then the colour will change to yellow. It is however, inherently non-lightfast – but it does fade beautifully! The only solutions are to store turmeric dyed items out of bright sunlight as much as possible and wash and dry them indoors. Plan on re-dyeing every year or so. That’s what the monks in Tibet do. Over-dyeing with woad does seem to produce a more resilient green. Over-dyed with cochineal produces a redcoat scarlet.
Because turmeric dyes substantively it can be thickened with gum and painted directly onto the medium and is a good dye to use for children’s projects.
The chemical that gives turmeric its colour is called curcumin (it has anti inflammatory properties when digested)
DYEING FLEECE or SILK WITH TURMERIC (no mordant required)
Mix turmeric to a runny paste and add it to your dye pot containing about 10 litres of water. Bring to the boil and simmer for an hour. Strain through a coffee filter or double layer of muslin to remove particles of turmeric. Add wet silk or fibre to the dye pot and bring the temperature up to a maximum of 180 degrees F, stirring constantly. Use a thermometer to make sure you do not overheat the dye pot. Hold the temperature for an hour. Turn off the heat. Leave to cool in the dye bath, and then wash thoroughly in cool water until the water runs clear. Dry in the shade.