•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
Ultimate Particle Size Distribution - UPSD
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.
This refers to ultimate particle size, it cannot be measured by using sieves, the units are microns. Testing equipment or a water sedimentation method must be used.
Typically it is expressed as cumulative undersize, that is, a series of percentage numbers matching a series of successively smaller micron measurements. Each of the numbers is the percentage of particles smaller than the specified micron particle size.
Comparative sedimentation tests in water can be also be done using a minimum of equipment. Where a range of particle sizes are present you can see them as layers after the sedimentation. Of course, a standard method needs to be developed so that each test uses a specific amount of water and clay or mineral powder. Clay powder should be prepared by pulverizing completely dry material so it slakes as much as possible in the water. The suspension should have plenty of water so that particles are free to fall.
VAL - Value (V)
Which clay contains more soluble salts?
Example of sedimentation test to compare soluble salts water extracts from suspended clay. This simple test also reveals ultimate particle size distribution differences in clays that a sieve analysis cannot do.
Can we ball mill a clay and make it more colloidal? Yes.
This 1000 ml 24 hour sedimentation test compares Plainsman A2 ball clay ground to 10 mesh (left) with that same material ball milled for an hour (right). The 10 mesh designation is a little misleading, those are agglomerates. When it is put into water many of those particles break down releasing the ultimates and it does suspend fairly well. But after 24 hours, not only has it settled completely from the upper section but there is a heavy sediment on the bottom. But with the milled material it has only settled slightly and there is no sediment on the bottom. Clearly, using an industrial attrition ball mill this material could be made completely colloidal.
Out Bound Links
SIEV - Sieve Analysis 35-325 Wet
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...
5: PTT - Particle Tests
'Slaking' refers to the breakdown that normally occurs when you immerse dried clay chunks or lumps in water (damp or wet lumps will not normally break down in the same manner because the wet clay resists the penetration of water). Typically the water attacks the surface and particles simply fall awa...
In Bound Links
AVPS - Average Particle Size (Microns)
SADR - Sieve Analysis Dry
By Tony Hansen