Steve,
You should check out some of Stuart Willis's hawks. The finish is spectacular. He does great work and is great guy to deal with. Hes the one who gave me the recipe. He does some really cool stuff with pewter too.
That makes sense on the acid. I guess it gets pretty dark as the heat gets applied. I suppose like anything else practice, practice, practice. Thats cool your dad has used it. It is an old muzzleloader recipe I guess. Well good luck and post some pics as you go along. :thumbup:
Larry