•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
Clays that have been transported by water from the site of their primary alteration and settled into layers. They are classified according to the geological period in which they were formed. Nature purifies these clay mechanically, removing gravel and sand, but contaminates them chemically or at the ultimate particle level, adding iron and fluxes. Vast deposits of secondary clays can be found in many places and materials having a wide range of properties can layer right next to each other. Ball clays, earthenwares and stonewares are secondary clays.
Out Bound Links
Most often the term stoneware refers to a high fired (about 1200C+) ceramic clay:feldspar:quartz blend that is semi-vitreous (not translucent and not zero porosity). To appreciate the scope that stoneware can encompass it is helpful to contrast it with porcelains (this description is for people who ...
A clay fired at low temperatures (cone 010-02) where it does not develop maturity (vitrify). The term earthenware almost alway refers to red burning terra cotta ware (although it is a somewhat more general term referring to a wider range of colors and more primitive forming and firing techniques). E...
'Terra Cotta' (Italian for 'cooked earth') is red burning earthenware. It has been made for thousands of years by indigenous cultures, most often unglazed. If glazed, high lead content mixtures have been traditional. It is fired at much lower temperatures than stoneware so, not surprisingly, it is n...
Ball clay is the most common type of secondary clay. They are much more plastic than kaolin because the particle size is much smaller. Ball clays are available with a wide range of plasticities (a pro...
Kaolinite is the closest thing we have to pure clay mineral. Clays that have been deposited at or near their site of alteration. They typically are contaminated by rocks and mineral particles that must be removed by processing. The cleanest and lowest iron clays are from this type of deposit. Kaolin...
In Bound Links
A refractory naturally occurring secondary clay. Fireclays are refractory because they contain high concentrations of Al2O3 and low concentrations of fluxes (like Na2O, K2O, CaO, MgO). Kaolins actually qualify as a super-duty fireclay because they contain almost no fluxing oxides (and are thus very ...
By Tony Hansen