@deafbeef
While making Hashmarks for @brightmoments Patagonia event last November, I saved the forge scale, the flaky oxide residue from forging process. I ground it into a powder and worked with a local printmaker to use it as a pigment in the gum-bichromate photographic printing process.
https://hashmarks.deafbeef.com
Limited edition print run now in progress, will ship soon.