Not sure if you guys know this, but the nuts from a Black Walnut tree is excellent for dying / coloring metal. We used to dye our Fox Traps this way. It is real easy to do.1) Let whatever metal you want dyed to set out in the rain and get a light coat of rust. This allows the oil to wash off, and the rust gives the dye a place to go.
2) Gather enough fallen black walnuts to cover the bottom of your pot in about 2 layers.
3) Start a fire and get the water boiling. (We would do this outside)
4) Throw in your steel and let it simmer for several hours. (Keep turning the metal so that the dye gets everywhere on them)
5) Allow to cool down and remove. Presto, the steel is dyed.
NOTE: This does not come off of your hands or clothes so use caution.