Frits are a combination of materials melted together to render them insoluble and resistant to acid attack. They are a method of introducing certain materials into a glaze which would otherwise be toxic.
Frits can be used alone as low temperature glazes e.g. raku or majolica but generally form the basis of glaze recipes to:
- Lower the melting point of a glaze as a flux
- Render otherwise soluble materials insoluble in the glaze (ie prevent soaking and crystallizing on pot surface)
- To give a more predictable and uniform rate of fusion (perhaps lower melting point)
- By introducing materials free of volatiles (prevent pinholing etc)
- To provide an even colouring effect from oxides and satins (avoid speckling)
- To stabilize a glaze before firing (prevent shrinkage cracks, peeling and crawling)
A frit melts very rapidly at a specific temperature.