Silica is the primary glass former in ceramic glazes. The majority of what makes up a glass or a glaze is Silica. When you are looking at a glaze or the glass in a window, the hard transparent material you see is Silica.
Silica (SiO2 or silicon dioxide) is also referred to as quartz or flint. They are all exactly the same things. Silica is the name of the chemical compound, quartz is the name of the mineral and flint is the name of the rock.
Silica is the most abundant compound in the earth’s crust. It is everywhere and in almost everything related to ceramics.
Silica has a high melting temp of 1715°C (3115°F). For perspective, cone 6 is approx 1220°C and cone 10 is 1300°C.
Silica has a low viscosity when heated, meaning it becomes very fluid and runny. This is why we also need Alumina in our glazes as a secondary glass former. Alumina acts as a stiffener to keep the liquefied Silica on the pot throughout the firing.« Back to Glossary Index