I Tried 8-18 Stainless and 316 stainless. First I attempted a few screws in a tiny sample. They did blacken but the coating is anything but durable and comes off while im drying them. I attempted an etch with muratic acid on the 316 and 8-18 stainless in various small experiements.
After trying and trying to get them to work on several different boxes of screws. This is pretty much what they all look like
