Mklamping Posted November 8, 2020 Report Share Posted November 8, 2020 Good afternoon, I am purchasing bisque that is fired to cone 04. I am using a low fire glaze (I have tried two different brands - Mayco and Blick) and brushing on two coats. I am then firing the pieces to cone 05. The glaze is shivering often on the edges and rims of the piece. What do you suggest I do differently? I have tried thinner coats and it helps some, but does not completely prevent it. should I fire the glaze to a different cone? Link to comment Share on other sites More sharing options...
Bill Kielb Posted November 8, 2020 Report Share Posted November 8, 2020 The glaze and clay are not a good fit. The coefficient of expansion of the fired clay and fired glaze are incompatible. If this clay has done this with two brand name lowfire glazes then maybe call and find out which glazes are known to work with it. Since this appears to be purchased bisque ware I would start with them. Do you have anyway of determining what this clay matures at? This claybody might mature at cone 6 or cone 10 in which case that would likely explain why two different lowfire glazes do not match it. Link to comment Share on other sites More sharing options...
Mklamping Posted November 8, 2020 Author Report Share Posted November 8, 2020 Thank you. The clay is Excel casting slip. Low fire C cone 04-06. Link to comment Share on other sites More sharing options...
Bill Kielb Posted November 8, 2020 Report Share Posted November 8, 2020 I would call excel. Since you get these bisque,, you are not casting with your own slip I assume. Link to comment Share on other sites More sharing options...
Mklamping Posted November 9, 2020 Author Report Share Posted November 9, 2020 Thank you. I am not, just purchasing from a company that makes them. Link to comment Share on other sites More sharing options...
Mklamping Posted November 11, 2020 Author Report Share Posted November 11, 2020 Do you think firing to cone 04 (the same as the bisque) will resolve? Link to comment Share on other sites More sharing options...
Bill Kielb Posted November 11, 2020 Report Share Posted November 11, 2020 No, I don’t think it will, just a mismatch in clay and glaze coefficients of expansion. My guess, something wrong with the claybody. Link to comment Share on other sites More sharing options...
Chilly Posted November 11, 2020 Report Share Posted November 11, 2020 13 hours ago, Mklamping said: Do you think firing to cone 04 (the same as the bisque) will resolve? No. might make it worse. Mismatched clay and glaze. Like putting petrol in a diesel-engined car. Doesn't work Link to comment Share on other sites More sharing options...
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