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Descriptions:
This presentation, led by Matt Katz, shares collaborative research on glaze chemistry and copper in ceramics.
Matt explains how his online teaching connected potters and ceramic engineers worldwide, leading to joint research with Sue McLeod, Chiara Matos, and Peter Berg.
Sue McLeod investigates cone 6 glazes using Stull’s glaze map and unity molecular formula (UMF). By systematically varying silica, alumina, and flux ratios (with controlled boron), she recreates Stull’s patterns at cone 6. Her results show:
Matte vs glossy surfaces can be predicted by the silica-to-alumina ratio (true mattes at ≤5:1).
Glazes become under-fired above ~12:1 silica:alumina or beyond certain alumina limits.
Crazing depends on both silica/alumina levels and flux ratio; lowering R₂O flux (e.g., sodium) reduces crazing.
Overall, Stull’s map reliably predicts cone 6 glaze behavior when boron and fluxes are properly tuned.
Chiara Matos tests whether copper is a flux. Using simplified glaze formulas where copper is the only alkali flux, she builds a Stull map that matches expected melting patterns. This confirms copper behaves as an R₂O flux and should be included in UMF calculations, implying other colorants may also need to be treated as fluxes.
Peter Berg studies copper leaching and toxicity. Using 4% acetic acid and ICP-MS testing at cone 04, 6, and 10, he shows copper release increases with copper content, flux ratio, and lower boron—but even worst-case levels are far below CDC toxicity limits. In practice, you’d suffer water toxicity before copper poisoning. Well-formulated low-fire and even matte glazes can be highly durable.
Together, the talks show how chemistry and mapping tools let potters design safer, predictable, and more reliable glazes.
