Walnut is a dye stuff that can be used on both animal and vegetable fibre without a mordant. Once you have set up the dye bath, add your fibre and leave it to take up the colour. With a solar dye bath, you might leave it for a week say….or longer perhaps.

A friend has sent in some dried walnut husks from her garden. These will leach a lot of colour when rehydrated.

The husks have been mixed with hot water and will be left on a sunny windowsill to encourage the colour into the water.