Which Carbon to Use?

Although some coal-based carbons are suitable for firing copper and bronze, I have recently decided to stick to coconut-shell carbon. For some time I had not been able to get a good contrast between the copper and the bronze in mixed pieces. This can happen for two main reasons:

1. Over-sanding prior to firing (this could cause particles from each metal to “bleed” into the other);
2. Oxidation of the copper in the process of firing.

I knew it wasn’t the first reason. Something was causing oxidation. After ruling out other possibilities, I replaced my coal carbon with coconut-shell. The differences were striking. Here is how the pieces looked straight from the kiln. I used my new firing method, 1:00 hour at 1450ºF in a fiber blanket box.

t-Straight from the kiln

Another great advantage to coconut-shell carbon is that although I used very little carbon, very little ash was created. I was easily able to vacuum the ash and re-use the same carbon over and over.

The carbon is coconut-shell, acid washed, size 12 x 40.

Bear in mind that probably not all coconut-shell carbons are the same. Different vendors may be supplying different brands. Moreover, vendors change their own suppliers and you may be getting a different brand even if you ordered from your regular vendor. It has happened to me more than once that I was working with one supplier, being quite happy with the carbon, and then the next shipment wouldn’t work anymore.

So I suggest ordering small amounts and testing them. I can’t afford to buy from every possible supplier and test, but I would be happy to test for you if you send me samples.


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