Fusion Frit F-644
$6.00 – $250.00
High-sodium boron-free frit
Used in crystalline glazes. Very high thermal expansion.
This frit has an incredibly high Na2O content coupled with very low Al2O3, that makes it potentially very useful in fixing glazes lacking sufficient clay content to suspend and harden them (substituting this enables lowering the feldspar and introducing clay to supply the lost Al2O3, for example).