•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
Mocha diffusion is a technique of layering slips onto ware so that the edges of the upper one bleed outward into the lower. An alkali/acid mechanism is employed. The lower layer is a typical water based slip (usually white or cream) that is gelled enough to stay stable on the ware and wet long enough to apply the upper layer. Plastic slips (those high in bentonite or ball clay) work the best. The upper layer is acid-based and stained and very runny, people use a wide range acidic solutions (like tobacco or lemon juice, vinegar). When the stained acid is painted over the wet base its edges bleed outward in accordance with the fluidities and degree of difference in pH. The effect survives firing well.
Mocca mugs by Victor Duffhues
M370 mug using M370 clear glaze by Victor Duffhues.
Out Bound Links
Creating a Non-Glaze Ceramic Slip or Engobe
It can be difficult to find an engobe that is drying and firing compatible with your body. It is better to understand, formulate and tune your own slip to your own body, glaze and process.
The opposite of deflocculation. Flocculation in a slurry can be a desired or undesired property.
For the latter, a ceramic glaze or clay slurry that would otherwise be thin and runny can be made into a gel by the simple addition of a flocculant. This is typically done to improve suspension prope...
Glaze slurries can gel if they contain soluble materials that flocculate the suspension. Gelling is a real problem since the glaze will not pour properly, pieces cannot be dipped without getting an excessively thick layer and the glaze does not drain off the ware to form an even layer. When water is...
By Tony Hansen