An ancient and traditional way to dye wool using crottle. A lichen found on rocks, particularly on stone walls. It takes time as the lichen needs to be fermented in ammonia for several months and then dried before using. It gives a reliable colour and dyes a lot of wool for a small amount. No need for mordants and I just put the dried crottle in a old pair of tights and boil it with the wool. A method used to dye wool for centuries. As with all natural dye stuff the colour is soft hue that can not be obtained from artificial dye
