Blue Spark is a glossy, royal blue glaze which develops small triangular dark gray metallic crystals that make this glaze look like lapis lazuli. This opaque glaze does not break over texture. For best results apply three even brush coats. Glaze may run. ___________ The Potter's Choice glaze series was designed with the potter in mind! These stunning glazes add fluid colours and effects to smooth or textured ware, with optimal results at Cone 5/6. To use these glazes is to step into different ceramic glaze traditions of many cultures throughout history. Check out AMACO's PC Layering charts to see all the amazing results you can try in your own studio! Reduction Effects in Oxidation Variety of Colours and Surfaces Cone 5 - 6 Food Safe (except PC-4 Palladium, PC-9 Vintage Gold and PC-64 Aventurine) Limitless Layering Combinations! Shake well before use. NOTE: Due to variations in raw materials used during manufacturing, we recommend firing glazed test tiles before using each new batch number of glaze. SAFETY WARNING: Tableware producers must test all finished ware to establish dinnerware status, due to possible variations in firing temperature and contamination.