Saturday, March 22, 2008

Heat Coloring Copper

Heat colouring copper is a very experimental and unpredictable process, determined solely by the temperature of the metal. One of the main things to remember is to go slow, and to heat the metal slowly to achieve the colours you want. The Copper will go through a series of gold, orange, pink, purple, dark blue, and light blue, before turning black. Here are some tips on how to go about this process successfully:

  • Cut and shape your piece of copper
  • Complete all shaping
  • BE SURE TO FINISH ALL AREAS WITH EMERY (SAND) PAPER BEFORE COLOURING. Any areas not cleaned properly will turn a brown colour, and you will have to clean the whole piece and start over.
  • Holding the metal in soldering tweezers, preferably with the tweezers holding as small a space as possible, start “painting” the metal very slowly with the soft flame of the torch. You really only want the tip of the flame to "lick" the metal, and can even heat it from a bit further away. Be very careful and do this gradually and slowly, removing the flame frequently to check the colour. If you heat past the colour you want, you will have to re-emery the surface and start over.
  • The metal should turn a gold colour, then orange, pink, purple, dark blue, and light blue. Because the process is so unpredictable, it is normal for parts of the metal to turn one colour and not cover an even surface, although this can be manipulated with small amounts of heat.
  • Once you reach the colour you want, remove the flame and blow on the piece of metal, to slow the process of changing colour. The colour may or may not change in this step, so it is advisable to watch the colour closely and remove the flame prior to the metal changing to the colour you want.
  • Place the copper piece aside in a place where heat will not reach it. Be careful that you place it on a clean surface—otherwise you may end up with solder or other dirt sticking to it and ruining the piece.
  • Many people have inquired about what to coat the pieces with to prevent the colour fading or oxidizing. I have tried wax and it has completely removed the colour. It has been recommended at that you use an oil-based polyurethane coating. I do not coat my pieces as the colour seems to hold up well, and have tried polyurethane coating, which made the piece turn orange.


Lynette said...

I have found that Renaissance Wax works really well, although it is a bit pricey! Johnsons paste wax also works pretty good, but can yellow silver so is better for copper. Great post!

knitsteel said...

When I was in grad school, people were heat coloring copper, for the red color, in a toaster oven. I don't remember what temperature they were setting it at. The toaster oven allowed them to get a consistent color over the entire surface.
It's worth experimenting with.

Future acrylic floor wax is a decent finish, but may still darken the color tones.

Amanda Conley said...

This is interesting because I was just doing some work with copper - and I noticed the color changes as I heated it, but do you know exactly how long the color holds? All of my copper pieces turn from shiny to brown after being in the air, in a pretty short amount of time (one to two weeks.) Of course I have not done a finished piece with a color, only polished, so it might oxidize differently. How long do yours last?

Ceridwen said...

Thanks! All the info I was looking for presented in a quick and concise way. Definitely coming back to learn more.

Julie B said...

Thanks for the info. Lots of very useful stuff. I've used Conservator's Wax and have found it works well. Similar to Renaissance Wax, but less expensive.

Verrel said...

I've been coloring copper since the early 90's it's certainly not hit or miss. Although it does take many, many, hours of practice. The colors I can obtain are copper, brown, purple, blue, green, yellow, orange, rose, and black. After the colors are obtained the piece is dipped in a special lacquer which holds the color. If you wish to see the copper I can do check it out on etsy, I'm the artist torch.

hez said...

hi verrel - i can't find the artist torch on etsy - can you post a link? thanks!

Lynda said...

I've been working with copper for the last year or so and have loved it. When coloring copper with heat, I found that if I hold the torch in one hand and a small spray bottle of water in the other, I can stop the color change pretty instantaneously with a spray of water.

Also found that if I "miss' a color I'm shooting for, I let the piece cool a bit. Then, hit it with the flame again. The colors change in a particular cycle and you have another couple rounds of them, before the copper goes dark.

Fresh Baked Designs

Tiana said...

Catherine, would you mind if I post my translation of this entry at my livejournal blog and at Russian LJ metalwork community? I think it's an interesting technique to try and to share information about.

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