HF-1 Black Black is a glossy obsidian glaze that produces an intensely dark surface and attractive high-fire effects at mid-range temperatures. High Fire (HF) The High Fire Cone 5 glaze series combines your favorites from the legacy Sahara and Celebration glaze lines. High Fire glazes produce interesting effects in both oxidation and reduction and should be brush-applied to bisque ware fired to Cone 04 for the best results. Reliable glazes for Stoneware and Porcelain Dinnerware safe Cone 5 - 6 Cone 5 = 1184°C (at 150°C/hour for the final 100°C of firing) / 2201°F ( at 270°F/hour in the final 200°F of firing) Cone 6 = 1241°C (at 150°C/hour for the final 100°C of firing) / 2266°F ( at 270°F/hour in the final 200°F of firing) Safety Warning Tableware producers must test all finished ware to establish dinnerware status, due to possible variations in firing temperature and contamination.
