| Monthly Tech-Tip | No tracking! No ads! | |
Both of these are mixed 70:30 kaolin:feldspar. Left is a fine particled kaolin, #6 Tile. Right, a coarser particled, less plastic material, EPK. During forming, the larger particles of the latter line up concentrically to the center better. This causes the body to shrink more along radius lines than along tangents, producing these cracks (many were made and they all cracked like this). In addition, bodies employing kaolin as the only clay in the recipe often fail like this because they lack the “stress-relief plasticity” that a bentonite or ball clay addition provides. The Tile#6 material on the left contains natural bentonite, so it can better relieve drying stresses.
| Materials |
Kaolin
The purest of all clays in nature. Kaolins are used in porcelains and stonewares to impart whiteness, in glazes to supply Al2O3 and to suspend slurries. |
| Materials |
EP Kaolin
A kaolin that gels slurries (thus handy to suspend ceramic glazes). It is plastic and fires white enough that it is also valuable in porcelain bodies. |
Buy me a coffee and we can talk