Granular Feldspar

Granular feldspar is a clay body additive. The main use of granular feldspar is for its visuals and texture. The exposed feldspar is visible as white rocks embedded in the clay. Its large size (measured in mm) makes it too large to flux and mature the clay body (unlike powdered Feldspar whose particles are measured in micrometers).

Granular feldspar is a distinctive element of Shiragaki ware. Feldspar, due to its LOI and thermal expansion, can cause the clay to burst. This phenomenon is known as ishihaze (rock explosion). The feldspar itself is called hazeishi (exploding rock).

• In this video, Akira Sakate says he adds granular feldspar to a slip he applies to his bowls.

Granular feldspar is a bit hard to come by as a commercial product in North America.

• Laguna does not supply granular feldspar (checked with sales in late 2023)
• Seattle Pottery Supply had pea gravel Custer Feldspar in late 2023. It was available in store but not listed online.
• Tougei Shop (Japan) sells granules about 1-3mm in size

Created 2024-03-17. Updated 2024-03-17.

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