Yesterday I mixed linseed oil and mineral spirit with ashes and chunks of charred wood from our outdoor fire pit. I used a rock to grind the sooty ash into the oil and spirit mixture, in a small dish. Then I dipped in my brush and made some paintings.
In the meantime though, the rough mixture I made was fun to work with.
A day later it's already fairly dry, and the charcoal seems fairly bound with the oily medium to the paper and canvas I worked on.
What started this whole business of mixing ashes with medium? A bit I read in Victoria Findlay's book about colour, the brown & black chapter in which she describes some of the dirts that artists use to make beautiful paintings.