A variety of terra cotta clay test bars (and a low temperature porcelain) that have been fired to cone 5. The measurement and weight data from these bars is entered into the appropriate recipes in my account at Insight-live.com; it uses that data to calculate shrinkage and porosities. I will also attach link this picture to each of the recipes. Some are quite vitreous and stoneware-like, some are in the advanced stages of melting, others could take more heat yet.
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