To create this speckled piece, Kingston, New York–based ceramicist Robert Kessler works with zinc-based glazes that form crystals when cooled slowly after firing. Visual variations are made by adding amounts of cobalt, zinc, iron, silver, and tin oxides. Photo 4 of 11 in ceramics by pulltab from Hand-thrown and Glazed

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4 of 11

To create this speckled piece, Kingston, New York–based ceramicist Robert Kessler works with zinc-based glazes that form crystals when cooled slowly after firing. Visual variations are made by adding amounts of cobalt, zinc, iron, silver, and tin oxides.