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Heat patina on copper

Stephanie,

For a long-lasting patina, try using the oven. Using various
temperatures and times will give you a wonderful range of colors. I
prefer to use a torch, but failing that, it’s the next best option.
To keep the colors I use a carnuba floor wax applied very lightly.
If your colors are disappearing when you spray, then they are not
deep enough.

regards,
Donna Blow, dzines by donna

In addition to my prior comments, the patina needs something to grab
onto. I usually sand or use a 3m abrasive wheel on my pieces. This
gives the patina a roughened surface on which to adhere.

Donna Blow,
dzines by donna

Hi Stephanie, A lot of what’s happening on your copper may indeed be
due to a lack of proper heat. When you heat copper and get beautiful
colors it is just a heat-accelerated form of oxidation forming on
the surface. I have honestly never tried heating copper with a heat
gun but I suspect insufficient heat may be the culprit. I’ve also
never run across copper colors from heat that disappeared when they
were touched. But there are many things in this world that I don’t
know about.

I have worked with quite a bit of copper in the form of sculptures
and the like though, so I can tell you a few things.

Like I said earlier, heat colors on copper are a type of oxidation.
Touching the surfaces of copper will leave traces of oil/sweat from
your fingers and, while the results are not immediately noticable,
given a couple of days ( especially if it’s highly polished) you’ll
be able to see clearly where it was touched. Big ol’ fingerprints
and smudges that definitely will change the colors where they are
found. If not covered with some type of surface protectant those
colors will rapidly fade to gradually deepening shades of brown.
Even if you never touched them those colors are temporary at best.
I’ve tried covering my colors with clear spray paint (both enamel
and acrylic), clear lacquer, polyurethane spray… all with the
same result, the copper colors that were so beautiful went away.
Something about a coating destroys the effect. Personally I believe
that the surface of the copper, when heated for color, is affected
on a molecular level on the very surface where the oxide is growing.
This surface manipulation of oxides causes the light that is
reflected off the surface to appear to be different colors due to
differing spectrums of light being reflected. Thicker oxides reflect
different colors than thinner oxides. A coating on the surface over
the oxides thoroughly changes things in that chemical reactions on
the surface will change the nature of the oxides chemically.
Coatings also will reflect their own characteristics, cover the
colors and change the way light reflects off the oxides. Gums the
colors right up.

I have yet to find a suitable coating that would protect the
beautiful colors.

There are some posibilities you might try for a heat source though.
I’ve used the kitchen stove. Ours is gas and requires lots of
practice to get good results. I don’t see why heat from an electric
range couldn’t be utilized as well. They certainly produce plenty of
heat. A simple electric hotplate might do the job.

I would recommend trying chemical manipulation to achieve varying
color effects. Liver of sulfur, gun bluing, different types of acids
all might work.

Sorry I couldn’t really help you out. I’ve struggled long and hard
to maintain colors on copper with only very limited success.

Mike

I've tried covering my colors with clear spray paint (both enamel
and acrylic), clear lacquer, polyurethane spray...... all with the
same result, the copper colors that were so beautiful went away.

Hello Mike,

I see you don’t name ranaissance wax. I use it for protecting copper
patina and am very satisfied with it. The copper surface looks very
near the original patina. The only problem can be that I don’t us
heat patinated copper for jewelry, only for panels, bowls etc. So I
am not sure about how skin-grease will effect the wax, but it is
worth a try. Hope it is the good solution for you,

Merleen.
Marleen B.Berg


Aventijnhof 11
6215 ES Maastricht, Nl.

Stephanie,

I also do a lot of work with copper and have found that everything
Mike has said to be true. It always saddens me to loose that
beautiful blue.

Bill Churlik
@Bill_Churlik
www.earthspeakarts.com

   I see you don't name ranaissance wax. I use it for protecting
copper patina and am very satisfied with it. The copper surface
looks very near the original patina. The only problem can be that I
don't us heat patinated copper for jewelry, only for panels, bowls
etc. So I am not sure about how skin-grease will effect the wax,
but it is worth a try. 

I did a number of fold formed wall relief sculptures over 8 years
ago. I colored the surfaces using an oxy/acetelyne torch and then
sprayed the surfaces with Krylon Crystal Clear acrylic coating. 8
years later the colors are still intact, no discernable change.
These pieces have been kept indoors except for one that I put
outside last summer just to see if there would be any change. So
far, there has been a slight deterioration. I am going to leave it
outside all winter and then evaluate it.

Joel Schwalb
@Joel_Schwalb
www.schwalbstudio.com