[TheForge] Putting an oxide finish on mild steel?

[Justin Fellenz]

I've been playing with this effect on the damascus wedding ring I made
myself. I found that if I heat it over the gas stove to where I just
see it darken and then take it off and let it cool slowly in air, I get
a progressively darker finish--it seems that being in the flame (I
guess like in a gas-welding environment) keeps the metal protected
somewhat..once I take it out of the flame the oxides seem to get darker
over time than they do in the flame. I haven't been able to come up
with anything reproducible either, but I haven't tried--I'm just
noodling. Maybe a known time in a known flame and then a known cooling
time would yeild predictable results. It also seems to work better the
more polished the surface.

Justin.

--- Steve Smith <sos at alum.mit.edu> wrote:
> 
> 
> Aaron Stavens wrote:
> 
> > I had another different piece of sheet steel I had welded on with
> E6013.
> > I had baked it in my kitchen oven and, unintentionally, it acquired
> a
> > dark blue color with purple and copper highlights. There is also a
> nice
> > iridescence in places. My friend saw this and liked it. So, I'm
> trying
> > to achieve a similar effect on the bracket.
> > 
> > I figured I would buff the bracket with a wire wheel and bake it in
> the
> > oven like I did with the previous piece. The baking didn't go so
> well.
> > All I could achieve was a very light translucent blue even after
> hours
> > in the oven. I assume my oven simply isn't hot enough, but I'm
> already
> > running it at the maximum of 550F. I also tried heating the bracket
> with
> > my welding torch. I achieved a whole rainbow of colors, but I
> couldn't
> > seem to control the colors I achieved.
> 
> You're right in describing this as an oxide finish. What happens is
> if 
> you have a thin enough layer of oxide, light hitting the surface will
> 
> interfere with itself (this thin the oxide is essentially
> transparent). 
> This reinforces some wavelengths and reduces others, which leads to
> colors.
> 
> I think what you have might be too thick a layer of oxide, giving you
> 
> the translucent blue. Try running it at several lower temperatures 
> (400F? 450F?) and see what happens. Make up some test pieces and take
> 
> them out of the oven at different times.
> 
> You might also try heating one end of a shiny piece of metal with a 
> torch. The colors "run" along the rest of the piece really quickly
> when 
> you get to the right temperature. It may be tricky to control, even
> in 
> an oven.
> 
> Steve
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