Sodium Feldspar, also known mineralogically as Albite (NaAlSi3O8), is the sodium end-member of the plagioclase feldspar series. Like potassium feldspar, it supplies alumina and silica alongside its primary flux, sodium oxide (Na2O).
Sodium is a more active flux than potassium. This means sodium feldspar begins melting at a lower temperature and produces a more fluid glass. Glazes made with sodium feldspar tend to have brighter, slightly cooler tones and respond vividly to coloring oxides, especially copper, which can shift toward turquoise in sodium-rich environments.
The trade-off is thermal expansion. Sodium has a higher coefficient of expansion than potassium, so glazes heavy in sodium feldspar are more prone to crazing (fine surface cracks). Many potters balance the two feldspars in their recipes to get the best of both.
Albite has been used for centuries in porcelain production, where it is often blended with potassium feldspar from different mountain regions to achieve specific firing characteristics.
Typical usage: 20 to 45 percent in cone 6 to 10 glazes. Often used in combination with potassium feldspar at a 50/50 or 60/40 ratio to balance expansion.
Western equivalents: FFF Feldspar, Minspar 200, Kona F-4, NC-4. Also used as a partial substitute for Nepheline Syenite with recipe adjustment.
Reviews
There are no reviews yet.