Went out to take a look at some massive colonies of Xanthoparmelia growing on a rock face. 5% potassium hydroxide test results in a nice deep yellow, almost green stain on the upper cortex. The medula is also K+, turning a deep blood red/orange. I blotted the soaked lichen on some paper and got this beautiful golden-rod ink. This ink was produced from less than a cm2 of lichen and a couple drops of KOH. I would love to experiment more given the abundance of this lichen and the small amount of material needed to produce the ink. This photo was taken 24hrs after staining the paper but I’d need to further test the colour fastness.
Edit: I am conscious of ethical harvesting practices for lichens, I normally only harvest for identification purposes and even then I try to only collect samples detached from the substrate.
What’s wrong with scraping up some lichen?
Lichens take a very long time to regenerate, most only grow a few mm a year. Some are protected or endangered on top of that. A good example is Lobaria pulmonaria, highly sought after by dyers because it produces a rich orange/brown dye in wool and other fibres. L. pulmonaria takes a considerable amount of time to grow, the thallus (body) only begins to reproduce after 25 years so is mainly found in older growth forests. Depending on the area, a person could come through and decimate a population just trying to collect enough material to dye a sweater. I’m not saying you should never harvest any lichen (its often unavoidable for ID purposes) but it is always a good idea to be conscious of your impact on a population of very slow growing organisms. The best way to harvest lichens is to salvage it off the ground after a wind storm or something like that, when lichens detach from the substrate they are rarely able adapt to the new environment and eventually die so its not as big a deal if you take that home because its going to decompose anyway. I have also seen where folks harvest no more than 1/10th of the population or harvest the outer edges of the thallus so that most of the colony remains. Really just depends.