Botz Stoneware Brush-on Glaze. Firing range 1220˚c-1280˚C 800ml BOTZ stoneware glazes are characterized by a particularly wide variety of colours and designs. Varying firing temperatures between 1220°C, 1250°and 1280°C can give some of the effect glazes a completely different look. The effects in general are more intense in the higher temperature range. For some glazes, a slightly uneven application may lead to even more vivid effects. The matt glazes are at their best from 1250°C on.