•The secret to cool bodies and glazes is alot of testing.
•The secret to know what to test is material and chemistry knowledge.
•The secret to learning from testing is documentation.
•The place to test, do the chemistry and document is an account at https://insight-live.com
•The place to get the knowledge is https://digitalfire.com
Clay, Silt, Sand Sedimentation Test - CSSS
This test procedure was employed in the Foresight Ceramic Database and now is available for those having an account at Insight-Live.com.
Accumulating test data using the variables defined in these procedures enables us to create tools that enable you to compare the physical properties of materials and recipes.
Use this test to make a rough characterization of materials that are a mix of sand, clay and silt. This test produces numbers that are quick to compare.
Each of these particle types are also chemically, physically and mineralogically distinct from each other.
Characterization of these materials in not firmly set in the ceramics industry as it is in soil science. In soil the size of the grain is most important, but in ceramics the properties of the grains (size, surface chemistry, etc) also determine their type. However for the purposes of this test a generalization is made.
Clays have thin plate-shaped particles held together by electrostatic forces, presenting a cohesive plastic mass when wet. Few clay particles are larger than 5 microns.
Individual grains of silt are approximately the same size in all dimensions and they vary in size across the range between 5 and 60 microns (of course there can be non-clay grains of silt less than 5 microns).
Sand particles are angular, often quartz, but also can be larger particles of any hard mineral. In ceramics the finest size sand that can be seen with the naked eye is about 80 mesh and detected by touch is around 140 mesh (106 microns).
Thus we set the division between silt and clay at 5 microns and between silt and sand at 100 microns. The latter can be measured using standard sieves, the former must be measured using sedimentation of instrumentation.
Clay - Value (V)
Silt - Value (V)
Sand - Value (V)
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By Tony Hansen