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.


9 Responses to “Which Carbon to Use?”

  • Kimberly Shaffer Says:

    Hi Hadar,
    Thank you so much for the info. I haven’t even fired silver, bronze or copper yet as I am waiting for my kiln. I have though finally made a few pieces in silver clay and it is very dry since I am waiting to fire. I can’t wait. I have bought bronze and copper clay and reading as much as possible about the best firing, keeping tools apart etc. This part of you blog is very informative to me. I ordered both carbon and coconut shell and was wondering which is best to use and when so this was a nice surprise to see in my email from you for us. I have so much to learn and your website and blog is so helpful. I can’t tell you how appreciative I am to you for all you do for the metal clay community! Thank you so much. I received an email from the woman that is giving your class in Grand Junction, CO and there is a space open now. I was hoping to write her back tomorrow when I know more if I can actually attend. My expenses are over the top with all my new materials and equipment. Do you know if you will be holding a class in the Front Range area (Denver, Colorado Springs, Fort Collins) of Colorado anytime in the future. I see that you won’t be in the near future as I did look at your schedule. I bought my coconut shell from Cool Tools for Metal. When I am ready to fire bronze and copper, I will try to do as you did and let you see the pictures of what it did. I bought a Paragon Xpress E12A Multi Media Digital Kiln since it had a brick interior. I hope it is going to be a good kiln for my needs. Thank you so much again Hadar!! You creativity and kindness goes hand in hand……..
    Very sincerely,
    Kimberly Shaffer

  • Kenji Says:

    Thanks Hadar for the info. I too have been using only coconut carbon as I’ve also found that it lasts longer for me. Plus, it’s also easier to get over here in France.
    Good to hear from you. You must be busy as it’s been a little while since we heard from you. Cooking up new recipes? ;o) Take care Hadar.


  • Donna Lewis Says:

    Hi Hadar, I assume the 1450 temp is in your top loader. Thanks for all the work you are doing and keeping us up to speed on your results.

  • Amy Atkinson Says:

    The results are amazing. I have a question, though. I remember when they introduced Bronze Clay at the last PMC Conference they cautioned against using acid-washed coconut carbon. Something about health hazards. Do you know anything about this? Would coconut carbon that has not been acid washed act the same?

  • Hadar Jacobson Says:

    When you purchase the carbon I suggest that you ask your supplier for the MSDS. I have checked MSDS from a few suppliers and did not find anything alarming so far.

  • Paola Says:

    Dear Hadar,
    THANK YOU SO MUCH FOR SUCH WONDERFUL BLOG! it is really amazing the way you have put everything together, so easy to understand. I’ve bought all your books but I haven’t sat down to play yet! First I needed to buy some equipment…I bought activated coal carbon to fire copper and bronze clay, but I haven’t use it yet…I just read about the coconut-shell, acid washed carbon…
    I live in USA (NC), I googled it but I couldn’t find any retail supplier…everything is whole sale…where can I find this product?
    …and when is the white bronze clay coming out to the market?

  • Karyn R Says:

    Hi. Is there a retail source for acid-washed coconut carbon? Everything I find is water-washed, or it doesn’t say. Does acid-washed versus water-washed coconut make a difference?

  • Melody Pierson Says:

    I bought two carbon – activated acid wash carbon & coconutshell carbon.

    I hope that’s correct. This is my first kiln (Firefly Digital Kiln) top loader. No success yet.

    I hope the carbon is not a factor!

    Melody Pierson

    Hadar’s work, clay and love of sharing and teaching is just intoxicating!

  • Cindy Pope Says:


    Is there a difference in the look of coconut vs coal carbon?

    I just ordered from a regular vendor and the carbon although marked as cocunut acts just like coal carbon (lots of ash, pretty colors and doesn’t cool down just burns up when removed from the kiln)

    I compared it to the coal carbon I have from a while back from the same vendor and it looks just like the coal carbon.

    I don’t have any coconut left to campare it to so I though I would ask you. Luckily I have more on the way from a different vendor.

    :)) Cindy

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