•The secret to cool bodies and glazes is a lot 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
Surface area is a physical property you will see listed on the data sheets of many materials. Individual materials can contain particles that have a wide range of sizes, shapes, densities, surface texture, reactivities and unique chemistries and mineralogies. More than any other material, the physical properties of plastic clays and clay-containing slurries are directly tied to surface area. In clays, the total surface area of all particles in a sample help explain important physical properties, especially plasticity and drying shrinkage. The smaller particles are the more they interact with each other (and any water between them). In clays, more surface means a greater ability of the clay to exhibit plasticity. Water acts as a glue, holding all the particles together because the surface chemistry of clay particles has an electrolytic affinity for water. The total forces by which they attract to it increase exponentially as surface area does.
Kaolins have comparatively large particles compared to ball clays and thus have a much smaller surface area. Bentonites have an even smaller particle size and a much larger surface area than ball clays. Only a gram of a plastic clay can have dozens of square meters (even hundreds) of surface area. This is orders of magnitude more than low plasticity materials.
One gram of processed hectorite has a surface area of 750 square meters!
A combination of surface area, surface topography, surface chemistry and surface electrolytics determines how plastic a clay is. This material is super plastic.
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Clay particles are flat and prefer to orient or arrange in a lattice-like pattern during mixing and forming operations. In bodies where they mix with other non-clay ingredients, they continue to arrange to the extent to which they can tolerate the disruptions of the others. The smaller the clay part...
Processed ceramic materials are typically ground to 200 mesh and feel very fine to the touch. With some you can detect some particle grains between your fingers. The amount of these "physical particles" can be measured by washing or shaking the ceramic powder through a sieve. Using water washing and...
Particle Size Distribution
When minerals and mixtures of minerals are ground into a powder a particle size distribution is produced, that is, populations of particles of various sizes. The relative sizes of these populations can be measured to rationalize the behavior of the powder in the ceramic process.
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By Tony Hansen