Updated: Oct 6, 2019
That the roots of tormentil had been traditionally used for a red dye was something I read and learned a while ago. So I was pretty happy to have both the opportunity and the motive to try it out for myself recently!
Tormentil (Potentilla Erector) is a small woodland plant with 4 green leaves arranged in a fan around the stem, and a 4-petalled yellow flower. It has strong astringent qualities so in days gone by an infusion was used as a wound wash, mouth wash and diarrhoea cure.
I'd never actually dug up a tormentil root before so didn't know how well it would work.
I was wild camping in a remote woodland in Northumberland and wanted to make an animal track trap - a way to see what critters had walked near camp during the night. I have done this in the past with an ink trap, some white paper, and some food bait - the animal has to walk over the ink then the paper to get the food, leaving its footprints behind.
Since I didn't have any ink and I saw tormentil growing nearby, I was struck with inspiration! I pulled up a few roots, smashed them with a rock, then boiled them along with some of the leaves in water for a time (maybe 30 minutes, maybe an hour - time passes differently in the woods). The leaves don't add to the dye but I wanted their astringent properties for a wound wash.
What remained was a very dark rusty orange/brown water! It wasn't exactly ideal. I'd say it half-worked! Anyway it was enough to leave a faint impression of tracks on the paper (when mixed with some cooking oil to prevent it drying out overnight).
In retrospect I should have used more root, crushed it up more, used less water (barely covering it), and boiled it for longer. Traditional foods, medicines and dyes tend to be a lot milder than modern chemicals (e.g. a herb tea needs to be infused for 10-15 mins, not the 30 seconds we're used to with a strong pyramid tea bag or instant coffee!). I also believe that if a bark or fabric were boiled in the liquid it would indeed get dyed - it's just not ideal as a transfer ink.
Well, it didn't go perfectly but was still my favourite kind of experience - a practical way to learn through doing!