Monthly Tech-Tip | No tracking! No ads! |
I made these test bars in order to guage drying and firing shrinkage and porosity (via the SHAB test), drying performance and soluble salts (via the DFAC test) water content and LOI (via the LDW test) and particle size distribution (via the SIEV test, the piece on the far left is going to be slaked again and washed through a root-of-two series of sieves). Notice all the bars are stamped with the lab code number I assigned. There is nothing like using a clay on the potter's wheel to get a feel for its plastic character. I found it to be quite sandy, but usable. If it could be sieved to a finer mesh, liked 42 or 60, it would be much more pleasant to use. Plasticity is fairly good, enabling me to pull walls quite thin despite the sand increasing friction, thereby increasing the tendency to twist at the base. It is also plastic enough to resist splitting at the rim as I pull it outwards. A closeup of the thrown rim shows the coarser particles.
The coarsest screen is at the top, the finest on the bottom. The top one has an opening of 425 microns (thus 425 micron and finer particles will pass through it, +425 micron particles will not). Its opening area is 180,000 square microns (425x425). Going downward, the openings have areas half that of the one above (thus, for the second, the opening area is 300x300=90,000 microns). Structural products industries, like brick, measure coarser particles than this, using 10-70 mesh. Using this series one can produce a standard measurement of the distribution of particle sizes in a material powder. The finer sieves (from 100-325) are only practical for wet processing (where the powder is water washed through the stack). In Insight-live the SIEV test (water washed) uses this series of sieves.
Tests |
Shrinkage/Absorption Test
SHAB Shrinkage and absorption test procedure for plastic clay bodies and materials |
---|---|
Projects |
Evaluating a clay's suitability for use in pottery
Would you like to be able to use your own found-clays in your production? Follow me as we evaluate a mystery clay sample provided by a potter who wants to do this. |
Buy me a coffee and we can talk