THE Materials Oracle
Join Date: Feb 2006
Location: Finally... home :-)
Bikes: Univega Alpina 5.1 that became a 5.9, that became a road bike... DMR TrailStar custom build
Is the stuff retailed as wood bleach pure oxalic? Or does it have some other stuff mixed in there? I'd recommend actually buying it from a schools/colleges/universities/research chemical supplies wholesaler, but you're gonna get stiffed for the cost of it.
The reason I'm suggesting oxalic is because you get a degree of passivation of the steel, without generating black iron oxide (magnetite), which is anodic to the steel underneath and while it protects the steel, it does so only until it's scratched - then it accelerates the corrosion.
It's the only oxidising reagent that's reasonably safe to use, cheap and doesn't grossly alter the observed colour fo the steel.