SD25010 White Opal DryMayco Stoneware glaze in 10 lb bag. Cone 6 oxidation (larger image): White Opal forms a clear to milky white gloss surface. One coat produces the clearest finish; subsequent layering increases the incidence of a white precipitate forming. Prominent white to bluish white colors will emerge where the glaze pools and gathers around surface texture. Cone 10 reduction (smaller image): White variation lessens leaving a transparent gloss with white pooling.