james howe's gunsmithing book has several formulae for post rust bluing treatments. near as i recall, they all had some combination of linseed oil, beeswax, and turpentine as the primary elements. not wanting to go to any trouble i just tried linseed oil straight out of the can and it works great. the main thing is, it won't affect rust which is what rust bluing is like most other oil type products on the market and rust bluing immediately after boiling is actually rather delicate and anything resembling solvent will damage it.
what i do is after the final carding while the parts are still hot from the tank i just rub a few drops of oil onto the metal by hand, just like i were touching up a stock. let it sit a while, few hours, something like that, and wipe off all excess with a clean dry rag, then oil it with gun oil the next day. the linseed oil seems to make the metal much blacker instead of a lighter near gray.
roger
