Hi - A glaze in the edge between a high alkali metal saturated iron glaze, and a high CaO semi-matte glaze. http://carol.knighten.org/2022-GlazeTests/2022-04-30-theEdge/ Carol -- ============================ Carol Marians (541) 296-4528 carol at knighten.org http://carol.knighten.org ============================