way to prevent steel from darkening during bake?

[FigureLLC]

i've noticed that steel darkens when baked, even if the temp is kept to 350. is there a way to keep this from happening? do any of the conversion coatings help?

applications where this would be useful: 1) brushed steel is nice and shiny, then when cleared and baked it darkens to a gun metal color. 2) with some light opaque colors, coverage mistakes are very unforgiving.

[CarWiz]

The different colors by heating are different oxidation stages. If you can stop the oxidation or pre-treat it should stop the transitions. The problem is that most passivation processes themselves change the color and can be destroyed by heat. And, if you're powder coating the steel then heating, the coating itself may provide some transition ions. If I recall, tin and zinc are non-transitional metals. If the steel was flash coated with one of these, it would retain it's color and maintain underlying patterns (dependant on plate thickness of course).

Does this help?

[FigureLLC]

good info, thanks! interesting you mentioned zinc... today i was looking at a sample piece i did. it was galvanized sheet that i took a brush wheel to, then cleared. the steel hadn't darkened and i was wondering why that piece was different.

what's it take to flash zinc something?

[CarWiz]

Caswell has zinc and tin plating kits. I don't know how large your pieces would be but zinc does take a lot of power to plate--About .14A per square inch according to the book. Tin is about .01A per square inch.

Caswell Inc. - Copy Cad® and Zinc Plating Kit

Caswell Inc. - Bright Acid Tin Plating Kit