On Tue, 30 Oct 2018 03:07:52 -0700, arjunsharma33 wrote:

Hi there-

I'm very new to metalworking and am just finishing my first big project,
a city skyline silhouetted offset from a background, all comprising
sheet metal steel.

To create contrast, I used an oxy-acetylene torch to heat patina my
background after cleaning it with an angle grinder. The patina came out
really nice, with brilliant blues and magentas.

The problem came after I threw a little Renaissance wax over the patina:
all the nice colors were lost and the foreground and background
basically look the same. I saw one post online that said those colors
cannot be clear-coated because the optic properties are lost, but it
recommended waxing.

Is there any good way to get those colors back? If I remove the wax, are
the original colors hiding beneath? Or will I have to repeat the heat?
In either case, is there a good way to protect the metal without losing
the colors?

Thanks for any help!!

The colours are due to interference effects of the thin layer of oxides
on the surface. The thickness of the layer is the same order as the
wavelength of light (very VERY thin). Waxing - or clear-coating -
increases the effective thickness of the layer (or perhaps changes the
percentage of light-loss at the oxide-wax transition) and you loose the
colours.

You may be able to get the colours back by removing the wax with solvent,
but I'd guess that it won't work that well - you might rub or scratch
through some of the underlying oxide layer. Be prepared to start again
from beginning of your surface prep.

And no, I don't think you can protect it without loosing the colours.