Nuka Glazes

Nuka is the Japanese term for rice bran and more importantly for my clay interests Nuka also  refers to a creamy milky white glaze traditionally made with ash from rice bran.  While a student at Clemson University, I saw work that had been glazed with a Nuka glaze.  I really liked the look of the glaze.  This is not a glaze that I formulated, but one I found after looking through old magazines and searching online.  This glaze isn’t made with rice bran ash and has been formulated with  the raw materials that you can get at a ceramic supply store.

Recipe for the Nuka glaze by weight:
Custer Feldspar         73.0%
Wood Ash                      8.0%
Nephelene syenite     10.0%
EPK                                5.0%
Silica                               4.0%

——————————–

Tin Oxide 1.0%

If you try out this glaze recipe send me a link to a photo of how it came out with your work.

Tea cup

Yunomi with nuka glaze

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8 Responses to Nuka Glazes

  1. Marcos Lewis says:

    is the wood ash a sub for rice hull ash?

    • mike says:

      Wood ash is not a 1:1 sub for rice hull ash. From the biology of the rice plant the rice hulls have a large percentage of silica which makes the rice hull ash more refractory than wood ash , so the silica and wood ash together are the substitution for rice hull ash. I got a few bags of rice hulls from a farmer the other year. I burnt the rice hulls and used the ash based on this glaze, but I had to change the percentages around some to get the glaze melt enough for a smooth glassy surface to form.

  2. Nancy says:

    Do you use washed or unwashed ash?

  3. jean szostek says:

    and is it hardwood, softwood or a mix off the two, i like these nuka very much
    thank you for sharing jean

    • mike says:

      The final result is a mixture of hardwood and softwood ash. The ash in the glaze is all hardwood ash. I have a smoker that I save all the ash from to use in my glazes. The anagama is fired with almost all pine.

  4. Arthur Lee says:

    Michael,
    I’ve just come into a supply of rice hull ash and am looking to experiment with nuka. To give me an easy starting point, would you be willing to share your recipe for nuka using rice hull ash (as opposed to wood ash substitutes)?
    Many thanks,
    Arthur Lee

    • mike says:

      Hello Arthur,
      I’m sorry about taking a long time to get back with you, I didn’t notice you comment until I was recently going through the spam folder section for my comments. When I first was able to get some bags of rice hulls. I took this nuka glaze recipe:

      Recipe for the Nuka glaze by weight:
      Custer Feldspar 73.0%
      Wood Ash 8.0%
      Nephelene syenite 10.0%
      EPK 5.0%
      Silica 4.0%
      Tin Oxide 1.0%

      took out all the wood ash, silica, tin oxide, and 3% of the Custer Feldspar.

      I made a test batch like this:
      Custer Feldspar 70%
      Rice Hull Ash 15%
      Nephelene Syenite 10%
      EPK 5%

      This one looked interesting in a gas cone 10 kiln, but the glaze was glossy with rough sandy feel to it from the silica in the rice hull ash not completely melting. This glaze look much more interesting in a wood kiln or soda/salt kiln.

      I had read some where that the original Japanese Nuka glaze was almost all rice hull ash, but I could never track down a glaze recipe.

      I also did a test batch of
      Rice Hull Ash 50%
      Custer Feldspar 25%
      Nephelene Syenite 15%
      EPK 5%
      Tennessee Ball Clay 5%

      This test batch didn’t come out very well. It looked liked semi-melted sand.

      Thanks,
      Michael

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