• Materials for Ceramics

F-75 Silica Sand

Notes

F-75 sand is a popular material used in modeling clay bodies to impart drying and firing properties. It is much cleaner than brick grogs.

Grain Shape: Rounded
Hardness (Mod): 7.0
Specific Gravity: 2.65
Bulk Density lbs/cu. ft. (Compacted): 104, (Uncompacted): 92
Moisture Content Dry (Max): <.1
AFS Grain Fineness: 76
AFS Acid demand (@pH 7): <1.0
pH: 7

Sieve Analysis: (as of Dec 2011 the material is a little coarser in the 70-100 mesh range)
USA Std. Sieve (Ind. % retained)
#30: 0.1
#40: 0.8
#50: 3.8
#70: 28.9
#100: 52.0
#140: 12.3
#200: 1.8
#270: 0.3

Related Information

How could only a 5% fine grog body be suitable for such large pieces?

Louise Solecki Weir working on one of her large sculptures. Sculptors can be passionate about the clay they use. For good reason, they have a lot to lose. While it might seem that Louise would be most concerned about drying shrinkage and drying performance (resistance to drying cracks), not so. To her, the ability to re-wet sections that dry out is paramount. And she has learned to overcome drying challenges posed by the high plasticity to benefit from the smooth texture, workability and rewetability it offers. How plastic is this clay (Plainsman F96)? It is a five-equal-parts-mix of silica sand/grog, ball clay, Lincoln fireclay, a low fire red clay and a medium fire red clay (there is no feldspar or silica). All four of the clays are highly plastic to super plastic. The body's drying shrinkage would be 8% if it was not for the 20% aggregate (a mix of fine 75 mesh sand with a small complement of fine 40 mesh grog) that reduce it to 6.5%. These offer a far higher surface area than coarse grog and provide channels for water to re-enter.

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