Heating copper
Between You and Joseph Owens

Joseph Owens
January 29 at 4:02am
Hi Collin,

I was wondering why the heating process for the copper is so important. I tried flame painting on a small piece in the shape of a butterfly which I still haven't completed, but all I did was heat my piece not to a red but just heat the piece, let it cool some then begin flame painting.
My question is why must you put yours in the oven? Does that make the colors come out better? I'm just trying to understand the process and if it is possible to just heat the copper with a propane torch?

Thanks for any info., still loving your work!!
Joe

Colin Alexander
January 29 at 10:00am
Hello Joseph ,
Thank you for the informed and interesting question , it's my pleasure to answer it .
Why I sometimes put a sheet in an oven to prime it , covers a number of reasons ;
A) torching alone is a localized process which leaves 'marks' and can't maintain consistent temperatures across the sheet , but an oven will . For example : the torch will heat a circular area to red in a minute or so , but the oven will heat the WHOLE sheet in a smooth , general fashion , or " priming" as I call it.

B) When you prime a sheet in the oven it will undergo the predictable colour changes over the entire sheet , to be taken out at any point when you like the colour . I cannot express to you how jewel-like and beautiful they are when they come out of the oven . Platinums , golds , silvers , dark purples , you'll see when you do it . Experiment .

C) Annealing the whole sheet in the oven (2 hrs @ 350) gives a dark -grey to black shade to work with , which is perfect for shading and can be torched off back down to the original copper colour , or etched/sanded down .

D) It is possible to use just a torch on unprimed copper , this is what I call a "raw" sheet . But the spectrum of colours becomes a little more limited . For Examlple : let's say you prime a sheet in the oven to a yellow gold colour , and then gently apply a soft slow heat with the torch . This will result in that area going a orange -red .
Now , if you 'bruise' the surface with a glancing hit from the torch you will get a rich green streak . Hold the flame with intent right over the area and you can erase it all back to copper and begin again , AD INFINITUM! Greens , blacks , browns, darkest blues, earth tones become possible after a priming .

So in effect , the oven pre- heat can give you more versatility , colours , and ' brushstrokes' . As you probably know annealing copper changes it's crystal microstructure , resulting in larger , chunkier , particles that when hit up with the torch , result in a more fractal , shimmering colours .
I hope that helps , and encourages you to verify my findings with your own experiments . I will upload pictures detailing some of these points .

Colin