- Cone 5-6 oxidation kiln - Developed with ceramic artist Nancy Sowder - Reduction-style depth with no reduction firing required - 36 nature-inspired colors, plus 3 fluxes - Durable mid-range finish for functional ware - Dinnerware-safe when used and fired as directed Speedball Mid-Fire Glazes were developed with Richmond-based ceramic artist Nancy Sowder, whose background in sculpture and lifelong focus on color informed the line, resulting in glazes that bridge functional pottery and fine art. A palette of 36 nature-inspired colors yields mottling and a sophisticated, reduction-like look in a standard oxidation kiln at Cone 5-6, with the kind of depth and movement that reads as professional in any maker's hands. No matter your skill level, Speedball Mid-Fire Glazes make it possible to achieve dazzling results with a single coat. You can also layer multiple colors—or add one of the 3 fluxes—for nuanced depth and variegated texture. Because they're fired at mid-range temperatures, these glazes deliver a durable finish for plates, mugs, and other functional ware made for everyday use. They are dinnerware-safe when used and fired as directed. For best results, Speedball recommends bisque firing to cone 05/04. Because every clay body and kiln varies, creating a test tile is the best way to preview color, texture, and overall performance. Avoid slow, controlled cooling cycles, as extended cooling can alter the final appearance of these glazes. Speedball Mid Fire Glazes can be high-fired to cone 10, however the finished appearance of many of the glazes may change at higher temperatures. We strongly recommend additional test tiles and conducting your own dinnerware safety testing before using the results on functional pieces.