Q: Why does my fired glaze have bubbles?

A: When working in ceramics long enough you will eventually encounter some technical defect based on a raw materials composition or firing cycle. Often upon investigation it can reveal interesting aspects of what is taking place within the kiln during the firing. Raw materials can change in organic content, particle size, pH levels, solubility, mineral content or gangue (pronounced “gang”) – a “tramp” material. Sometimes changes occur over a period of time, or in the next batch of material. It is useful to understand the chemical composition of materials and how they influence the melting characteristics in glazes.