With this glaze it’s all about shrinkage trick. Glaze is mostly made out of porcelain and ball clay, so it needs longer soaking time. It’s fired between cone 8 and 9, depends of procentage of the ingredients. During the firing process its shrinkage is bigger than the shrinkage of clay itself. It makes beautiful surface of melted cracks and little craters. Its downside is that it can deform thin objects.
Neverless this glaze is perfect for combining with other colour glossy glazes. It just makes amazing unpredictable effects.