What are frits?

Some of the oxides needed to make glazes have raw material sources that are not convenient or practical to use. Raw materials can be very soluble (dissolve readily in water), may not be stable in the atmosphere or may contain additional oxides not wanted in the glaze. Needed oxides can be made available in usable form by combining them in an industrial process called fritting.

A frit is a collection of raw materials (a glaze recipe) which has been melted to form glass containing the desired oxides. When melted the mixture is rapidly cooled and ground up into a fine powder ready to be mixed with other raw materials in the glaze making process. Frits are often complete glazes in themselves designed for particular purposes. Mostly, however, they are combined with other raw materials to make new glazes. They are particularly useful for making low temperature glazes as commercial versions are designed with low levels of Al2O3 and SiO2..

Materials such as feldspars, wollastonite and talc are really naturally occurring frits created by heat and pressure in the earth's crust.