Mayco Crystalites Crystal Glaze for Ceramics - Set of 12 Colors in 4 Ounce Jars with Free How to Paint Ceramics Booklet Mayco Crystalites Crystal Glaze for Ceramics - Set of 12 Colors in 4 Ounce Jars with Free How to Paint Ceramics Booklet These beautiful glazes transform in the kiln when small pieces of glass burst into color and intricate pattern during the firing process. Use alone for stunning effects, in glaze combination or simply as an accent to your design. Crystal glazes were designed to mature at cone 06/05. Apply to shelf cone 04 bisque. AP Certified Non-Toxic. Stir frequently as crystals tend to settle in the jar due to their weight.