•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
Refers to the period in firing where the last of the mechanical water in body and glaze are being released. Firing can normally proceed quickly after this water has been ejected (up to 750C/hour is common in industry). Typically firings are taken to the boiling point (or slightly beyond) and held there for the amount of time necessary to remove all the water (the "water smoking soak"). The degree to which the drying process has removed water determines not only the soak time needed at boiling point, but also the temperature at which the water smoking soak can be conducted.
Contrary to what you might assume, for well dried ware this smoking is more effectively conducted beginning at 140C and proceeding gradually to 260C. However, for a typical studio potter, care and testing are needed, since ware is normally only air-dried when it goes into the firing and bodies are more plastic and fine grained.
Put almost-dry ware into a kiln. This happens!
An example of what can happen if ware is heated too fast during early stages of firing. This bowl was not quite dry on the base, it is Plainsman M370. Even though the firing proceeded to 220 degrees and soaked for an hour, it was not enough time for the water to escape before the second step in the firing schedule.
Out Bound Links
In most electric periodic kilns firing schedules are programmed into electronic controllers to control the rate-of-rise, soaking time and often the cooling curve. In industry firings are very fast, optimization of every stage is absolutely critical, in hobby ceramics and small companies firings are ...
At it most basic level, firing is process of heating a clay (or recipe of clays and minerals) to a temperature sufficient to fuse the particles together. However today, each type of ceramic has its not only its own firing temperature, but also schedule (control of the rate of rise and fall of the ki...
Decomposition is the breaking of inter-molecule bonds during melting in the kiln. To understand it we need to understand elements, oxides, compounds, solutions and mixtures (from the chemistry jargon point-of-view).
"Elements" are one kind of atom which cannot be broken down any further (except b...
In Bound Links
Ceramic Thermal Events
Many ceramic problems relate to a lack of understanding about what is happening at each stage of a firing, there are just so many materials that are doing so many things. This part of the database wil...
Firing: What Happens to Ceramic Ware in a Firing Kiln
Understanding more about changes are taking place in the ware at each stage of a firing and you can tune the curve and atmosphere to produce better ware
By Tony Hansen