Copper and Silver Mokume-gane from Metal Clay
I didn’t think it was possible to make mokume-gane with a combination of copper and silver clay. I knew that the two metals won’t stick to each other, and if they do, they will alloy into a messy blob. I did try to make a gradient surface with copper and silver and ended up with sad results. But then someone asked me “Have you tried?”, and since then I couldn’t get the idea out of my head.
What if, I speculated, I fire at such a temperature where the two metals start to bond but not alloy yet? If this works, then it’s all about finding the correct temperature. (Whenever I ask my husband for his opinion on issues like this, he says: “firing schedule.”) The piece featured in this posting is my first attempt, no loss of silver whatsoever. Here is what I did:
I made the piece (see more information below).
I used a front-loader muffle kiln with a fiber blanket box. I fired the first phase on top of carbon: full speed to 1100°F/538°C, holding 10 minutes. To be safe, I fired inside carbon for 30 minutes. This is how it looked after the fires phase:
If I had made this piece with White Bronze (which I have done in the past), the White Bronze part would look almost as dark as the copper. You can see how white the silver areas are.
Then I started the second phase at the low temperature of 1200°F/650°C. Fired for 2 hours in carbon. I did not try to break the piece! Since the backing layer is copper, which is hard to sinter at this temperature, I sanded the back of it with 220-grit sandpaper. I saw some powdery areas.
I raised the temperature 20 degrees at a time. Each time I fired about 1:30 hours. The piece was fully sintered at 1320°F/716°C.
The mokume-gane part is treated with Baldwin’s Patina.
The question is: did the piece sinter because it was fired at the correct temperature, or because it was fired so many times?
When I fire mokume-gane with copper and White Bronze, I repeat the second phase of firing, to compensate for the low temperature. Surprisingly, in my front-loader, I fire White Bronze at exactly this temperature (1320°F/716°C). I am going to assume that what made it work is both temperature and repetition, so in my next attempt, I am going to use exactly the firing schedule that I use for copper and White Bronze (all firing schedules can be found in my instruction manual).
As for constructing this piece: regretfully, I cannot give instructions here for making this mokume-gane design and others because this is what I currently teach in my travel-teaching workshops, and it would be unfair to the people who pay to take these workshops. As far as I know, there are still a few spots available is my workshops in Dallas (with PMC Connection), TX; Brighton, MI and Saint Joseph, MI; and Rochester, NY (for details see my travel teaching schedule). There is also room in my Intensive classes at my studio. The rest of the workshops seem to be full.
Or, you can wait for my upcoming book, which includes more than 50 projects for different mokume-gane designs and techniques.
My thanks to Mary Ellin D’Agostino for her tips and suggestions.