Thread: rebluing

A bit of a side note, but it's my understanding that the cold blues are actually just a surface layer of selenium dioxide. In effect you're doing the same thing with cold blue as drawing on it with a vivid marker.

The cold blue seems to have a mild degreaser or acid to help it grab which might be why things rust if you don't thoroughly wash and neutralize the part after cold bluing. Might also be some sort of salt in the solution. I did one old gun with it and as Bill999 noted, it rusted like crazy even with heavy oiling - anywhere the oil thinned, it would bloom rust. That experience led me to experiment with it on pieces of metal and best solution I could find was to scrub the parts in a tub of water and sodium carbonate, then rinse heavily, dry with air and then oil. The parts that were washed in the basic solution then dried and oiled rusted a lot less than unwashed or water rinsed only parts, but they still rusted more than any bluing, and the cold blue rubs off easily, so it's one of those things that doesn't really stack up as worthwhile in the end.

Surface prep's the key on any bluing - any flaws you can see before will be there after. Blueing hides nothing, really you're just changing the colour of the metal and getting a rust resistant finish at the same time Since it's a mauser, a rust blue would be very appropriate for such an esteemed gun