Christy Ann Posted August 13, 2022 Report Share Posted August 13, 2022 I made an underglaze test tile on Minnesota Clay 03 biscware using underglaze with a clear glaze on top and this came out fine. Then, on a sculpture, I applied an underglaze to Minnsota Clay 03 greenware. This came out fine. Following bisc, I applied a clear coat of glaze and fired the piece at Cone 6. The final piece had very large bubbles and blisters on it. My instructor could not explain why this happened. Another instructor thought the problem might be that I overwork my pieces, creating a very smooth outer layer. The piece appeared to be dry for bisc after drying out in the air for several weeks. I wonder if the glaze simply cannot tolerate both the heat from the bisc and from the final, cone 6 firing. Does anyone have a good explanation? This is the second time this has happened to a major piece in the last two years. The first time, I used Amoco Velvet underglazes. This time I used a Bell underglaze. Quote Link to comment Share on other sites More sharing options...
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