Comparison of Clays

Kaolin

Kaolin	Notes
EP Kaolin	Most glazes typically use EPK for glaze suspension.
Tile 6 Kaolin
Helmer Kaolin	Use for flashing bodies and slips. Contains some coarser (~50 mesh) particles.
Grolleg Kaolin	Very white, but also more expensive. Does not suspend glazes as well as Tile #6 or EPK.
Optikast Kaolin	Very low plasticity. Advertised as a casting slip ingredient.

For glazes,

EPK, Tile #6, and others are "default" kaolins. They're cheap and suspend glazes well. Use whatever is most readily available to you.
Use Grolleg when you must have a iron-free glaze or can justify the extra cost.
I don't recommend Helmer in glazes because of the larger particles that must be screened out.

For clay bodies and slips, use

Grolleg for white and translucent porcelains (see Porcelain Formulation)
EPK / Tile #6 for white porcelains
Helmer for Alkali Flashing clay in Soda Firing or Wood Firing

Ball Clay

Ball Clay	Notes
Kentucky OM4 Ball Clay
Bell Dark Ball Clay
Tennessee 10 Ball Clay	Lower silica content than most American ball clays, yet still has high plasticity.
## Stoneware Clay

Clay	Notes
Goldart	Higher plasticity than kaolins, but less than ball clays. Matures at cone 10. Iron speckles.
Hawthorne Bond	Contains larger grains (sold in 40 and 50 mesh sizes). Iron speckles.

Created 2024-02-19. Updated 2024-03-09.

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