A glaze problem solved

I use 33% barium carbonate in my copper blue glaze. About a year ago I started getting some bubbleing where it got a little thick. Lots of seconds. I tried other bariums but they all seemed  grainy. Finally Sheffield pottery came up with a smooth precipitated barium. Problem solved.

This material is completely smooth and fine. Overlapping glaze is not rough any more.

Michael Cohen   Website pics on CD 042


2 Responses to “A glaze problem solved”

  1. 1 Alex July 11, 2009 at 9:29 PM

    So what is the difference in the forms of barium? Presumably, since it was precipitated, that implies it was made into suspension, then de-watered. Okay, so how does that make it melt differently? Is it finer?

    Glad to hear it made such a difference in the glaze finish.

    (an aside… Mike- You look awesome! Every time I see you, there’s less of you there to see! I need to meet your trainer.)


    • 2 asparagusvalleypottersguild October 10, 2009 at 9:02 PM

      The Barite (as it comes from the mine) is thrown into acid that dissolves it. Then it goes through some other arcane
      processes. Then it is mixed with carbon dioxide gas, dried and milled. (This is why it’s $53.- per bag!) This new Barium Carbonate is fine and smooth out of the bag. My old stuff looked pebbly but felt smooth.
      Also my old Barium glaze sunk to the bottom like cement and took half an hour to mix up. (Even with suspenders)
      The new glaze stays suspended with nothing added and two minutes to mix up. When fired to cone 7 it comes out smooth, just like the ancient Barium.
      It comes from Georgia. Chemical Products Corporation C.P.C. Type FF Brown bag with Red lettering.
      Michael Cohen

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