This is unlike some raw materials which often melt suddenly. These melt fluidity tests compare the flow of a boron frit across 200 degrees F. It first starts flowing at 1550F (although it began to turn to a glass at 1500F) and is running off the bottom of the runway by 1750F. The Gerstley Borate, on the other hand, goes from no melting at 1600F to flooding off the bottom by 1650F!
The Chemistry, Physics and Manufacturing of Glaze Frits
A detailed discussion of the oxides and their purposes, crystallization, phase separation, thermal expansion, solubility, opacity, matteness, batching, melting.
The melting temperature of ceramic glazes is a product of many complex factors. The manner of melting can be a slow softening or a sudden liquifying.
Frits are used in ceramic glazes for a wide range of reasons. They are man-made materials of controlled chemistry with many advantages or raw materials.
|Tests||Frit Fusibility Test|
|Oxides||B2O3 - Boric Oxide|
|Temperatures||Common frits begin melting (1400F-)|