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Heat Patina on Copper


#1

I am using a Wagner paint stripping heat gun to add a heat patina to
Copper wire & sheet.

Once the piece has cooled, why do the beautiful colors disappear
when I touch them? It seems if I run my finger over them, they
vanish like magic. Am I doing something wrong? Could it be that the
heat gun isn’t penetrating the copper as much as a torch might?

Let me say that I do not have the facilities to use an open flame of
ANY type. This is why I tried to use a heat gun.

Also - how can you preserve these colors? I tried spraying a
beautifully colored piece with Acrylic spray only to see the colors
disappear in front of my eyes.

Please Help.
Thank you - Stephanie


#2

Hi Stephanie - there was a great thread on this in the summer. I was
also asking about preserving colors on copper, and got lots of great
answers.

What I’ve since found is that you really have to draw out the colors
multiple times – draw with heat, quench in water, dry it, draw
again, quench, dry, draw – to get them to “stick”. If I just do a
light surface coloration (drawing just a little bit of the color to
the surface), it disappears upon quenching or with spray acrylic. I
can now bring out the colors I want - blues, purples, rich oranges.

I will look for the answers I got as there are some that didn’t post
to the whole list. I know there are some really good copper artists
out there with lots of experience, who know more about the properties
of color-drawing than I.

Roseann


#3
   Once the piece has cooled, why do the beautiful colors
disappear when I touch them?  It seems if I run my finger over
them, they vanish like magic. 

Hi Stephanie,

Basically the reason you have the colors is a thin film which alters
how the light reflecting to you is filtered. The thickness of the
film changes which colors are removed, and which left. Because it is
a thin film the moment to touch it or put oil or a sealer on it the
lighting conditions change and usually the surface is damaged.
Nicholas Lacquer and Incralac are both supposed to let you keep the
colors while still protecting them. best Charles

Interference colors are explained here:

Here is a similar coloring method.

and from: http://www.ganoksin.com/borisat/nenam/cupric.htm

The finished product may also have some form of protective coating,
although this patina is tough and not liable to damage if applied
correctly.

Traditionally these would include waxes, vaseline and oils. Also
available are the spray sealers and lubricants mentioned above. These
work as water does in intensifying perceived color on the patina
surface. The exact effect will depend upon the refractive index of
the coating involved, its evaporation rate, viscosity, etc. One
should make samples with various colors and different coatings for
reference. Oils and waxes tend to darken the color. The spray
acrylics tend to make the patina resemble green paint and I usually
use them sprayed from a distance for a thinner more subtle effect. In
general the use of such coatings is for aesthetic reasons rather than
protective.

My favorite is clear auto enamel: intended for outdoors, intended
for different temperature ranges, intended for metal. Nicholson
Lacquer (used on High School marching Band instruments) is very good.

Charles Lewton-Brain/Brain Press
President, Canadian Crafts Federation
Box 1624, Ste M, Calgary, Alberta, T2P 2L7, Canada
http://www.brainpress.com
Tel: 403-263-3955 Fax: 403-283-9053
@Charles_Lewton-Brai1


#4

Hi, are you making sure that the metal is VERY clean before heating?
That is the only thing I can think of, though I have only done heat
patinas with a torch…

Good luck!
Cindy
Cynthia Eid
http://www.cynthiaeid.com/