Most of you will recognize this widespreading lichen in bright yellow. If it grows in shade the colour is more grey green or greeny bluish. It grows on rocky surfaces, tree barks, pavements, timber, roofs and likes salty atmosphere. I have noticed, that while one tree can be almost covered with it the one growing right next can be completely lichen free, although they might both be the same species. It’s quite easy to peel it off the surface, especially after a good rain and the books recommend to collect plants from sunny places as they contain more dyeing acids.
Xanthoria Parietina can be either boiled, giving yellow towards tan or fermented, in which case it should give pink, puce or deep plum. And blue!
There is a simple test by which to know if a lichen will yield its dye by fermentation. The presence of two of the acids that yield a deep red or purple dye when fermented in ammonia can be detected by a simple household bleach containing chlorine. If a drop of this is applied to the plant and it turns red, this lichen will give dye by fermentation. If not, then boiling is worth trying. (1)
After I applied a drop of a houshold bleach it instantly turned red where the bleach touched the plant.
I dried and then finely crumbled the lichen, put in a jar and poured solution over : one part household ammonia to two parts rain water (soft water is recommended)
Now it’s sitting wherever it is the warmest, books recommend 13-24 C degrees (1). At first the color was deep red orange, after four days it’s turning towards red. I stir/aerate the mixture 5-6 times a day to encourage fermentation for which oxygen is needed ( no explanation of this in the books), putting the lid quickly back on so that ammonia doesn’t escape. The smell is so pungent I wouldn’t like to keep the jar open anyway.
I should wait at least 3-4 weeks before the dye is strong, but as this is just an experiment I will dye with a little of the mass after each week to see how the colour develops and strenghtens. Will keep you posted.
(1) Dyes from plants, S. M. Robertson