Plainsman Clays | F3249
Ferro Frit 3249
Frit 3249 is a magnesia borosilicate frit with very low thermal expansion. A small addition is a standard way to stop a glaze crazing, though it melts much hotter than a low fire frit.
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Frit 3249 is a magnesia borosilicate frit, and unusually it contains no sodium or potassium at all. Those two fluxes raise thermal expansion more than any others, and leaving them out does more to keep this frit's expansion low than magnesia does. A small addition, under a tenth of the recipe, is the usual dose against crazing. It flows around 1260°C, much hotter than a low fire frit, so a recipe that takes it in loses melting power and can come out stiffer and drier than before. It also contains a lot of boron, so using enough of it to supply the magnesia changes the boron level too. Magnesia mattes a surface and pulls colours towards pastels.
- Magnesia borosilicate frit with no sodium or potassium in it
- Very low thermal expansion, the usual cure for crazing
- Flows around 1260°C, much hotter than a low fire frit
- High boron, and magnesia mattes a surface
- Can be used to lower thermal expansion in a glaze
