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For cross reference to old Mason stain part numbers, and a list of chemicals in each stain, please go to the Mason Stain site.
Firing Temperatures can only be a rough guide. Firing at 2200F on a slow schedule may give the equivalent maturing as firing at 2300F on a fast schedule. The cycle, atmosphere, and rate of cooling with affect the color.
Zinc Oxide influences the color in a glaze more than any other element. Generally, zinc-less glazes should not contain magnesium oxide. Some colors containing zinc are to be used in a zinc-less glaze. The zinc in the color is in a combined form and will not harm the color, but free zinc oxide in the glaze can destroy the color.
Calcium Oxide content as calcium carbonate should be between 12-15% for best color development. Adding the molecular equivalent of calcium oxide with wollastonite, a natural calcium silicate, often gives better uniformity. The increased silica from the wollastonite must be subtracted or the glaze will have a poor surface.