•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
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 kiln). In addition the atmospheric pressure and atmosphere itself within the kiln are controlled for many types of firing, either by restricting the amount of oxygen in the chamber or replacing it entirely by another gas (like nitrogen). In addition kilns subject the load to drafts to help even out temperature and atmosphere and carry away water vapor and products of combustion and decomposition of bodies and glazes. Firing also varies in the types of fuel that are used (e.g. coal, gas, wood, sawdust, oil, electric) and the type of kiln (kilns vary widely in the way they deliver heat to the ware and channel it out).
Out Bound Links
Most potters and sculptors fire in electric or gas kilns, these are often computer-controlled. However the use of traditional techniques, some very ancient, is still very popular. It is in this sense we use the term "primitive firing" (not because it does not use technology!). The scope of technique...
Salt, soda firing
Salt firing is a process where unglazed ware is fired to high temperatures and salt fumes are introduced into the kiln chamber (normally by a spray in the burner ports). The sodium in the salt combines with the silica and alumina in the clay to form a vapor cloud that glazes the ware. Salt glazed wa...
A kiln atmosphere which is deficient in free oxygen. In traditional ceramics, reduction firing requires a specially designed fuel fired kiln that restricts the flow of incoming air so there is enough to burn the fuel and no more (in some cases it is restricted so that is actually less than enough to...
A firing technique used by necessity in many countries and by choice in others. In a properly designed kiln wood is capable of delivering high temperatures so it is possible to make stoneware and porcelain. The kiln chamber in a wood kiln subjects the ware to alot of ash and smoke and this profoundl...
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 ...
Manually program your kiln or suffer glaze defects!
There is no other way to do a drop-and-hold firing but manually program your computer controller.
What is drop-and-hold? It is a firing that holds at the top temperature only long enough to even ou...
In Bound Links
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 th...
The practice of slow-firing ware through the critical temperature surrounding the boiling point of water. This is done in situations where a drier is not available, it prevents cracking and explosions associated with steam trying to vent out of ware that is not completely dry. When ware has a thick ...
By Tony Hansen