Cone 6 Calcium Matte v2
Recipe
Notes
This is an adjustment to the original G1214Z recipe. The chemistry of this is the same, but the 37 raw kaolin in the original has been split to a combination of raw:calcined kaolin to reduce drying shrinkage (preventing cracking as it dries and crawling during firing). If unavailable, you can make your own calcined kaolin by roasting the powder in a container in a bisque firing. Like G1214Z, this achieves a mat surface by incorporating a very high percentage of CaO in the chemistry. While visually appealing surfaces can be achieved, especially with slower cooling, leach testing should be done if metal oxide pigments are being used. For 3000 grams we use 2600 water to get 1.45 specific gravity and good flow properties (no Epsom salts should be needed to gel the slurry, it is naturally thixotropic).
Description
This glaze was born as a demonstration of how to use chemistry to convert a glossy cone 6 glaze into a matte.