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This DFAC test disk shows the incredible drying shrinkage that a ball clay can have. Obviously if too much of this is employed in a body recipe one can expect it to put stress on the body during drying. Nevertheless, the dry strength of this material far exceeds that of a kaolin and when used judiciously it can really improve the working properties of a body giving the added benefit of extra dry strength.
| Minerals |
Ball Clay
Ball clay is the most common type of secondary clay. They are much more plastic than kaolin because |
| Tests |
Drying Factor
The DFAC Drying Factor test visually displays a plastic clay's response to very uneven drying. It is beneficial to show the relative drying performance of different clays. |
| Glossary |
Drying Shrinkage
Clays used in ceramics shrink when they dry because of particle packing that occurs as inter-particle water evaporates. Excessive or uneven shrinkage causes cracks. |
| Materials |
Ball Clay
A fine particled highly plastic secondary clay used mainly to impart plasticity to clay and porcelain bodies and to suspend glaze, slips and engobe slurries. |
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