Ceramic flux

A ceramic flux functions by promoting partial liquification in clay bodies and glazes. Fluxes are used in glazes to lower the high melting point of the glass formers silica and boric trioxide. The most commonly used fluxing oxides in a ceramic glaze contain lead, sodium, potassium, lithium, calcium, magnesium, barium, zinc, strontium, and manganese. These are introduced to the raw glaze as compounds, for example lead as lead oxide. Boron is considered by many to be a glass former rather than a flux.

In clay bodies a flux creates a limited and controlled amount of glass, which works to cement crystalline components together. Fluxes play a key role in the vitrification of clay bodies by reducing the overall melting point. The most common fluxes used in clay bodies are potassium oxide and sodium oxide which are found in feldspars. A predominant flux in glazes is calcium oxide which is usually obtained from limestone. The two most common feldspars in the ceramic industry are potash feldspar (orthoclase) and soda feldspar (albite).

References

• Epplar, Richard A., Obster, Mimi. Understanding glazes American Ceramic Society. Westerville, Ohio. 2005.
• Daly, Greg. Glazes and glazing techniques:A glaze journey Gentle Breeze Publishing. Kenthurst, Australia. 1995.
• Dinsdale, Allen. Pottery science: Materials, processes and products. Ellis Horwood Limited. Chichester. 1986
• Katz, Matt (September 2012). "Boron in Glazes". Ceramics Monthly Magazine (Columbus, Ohio: American Ceramics Society). 

See also

• Secondary Flux