Monthly Tech-Tip | No tracking! No ads! |
In bisque kilns ware is being fired for the first time. If pieces are thick and the rate-of-rise is too fast then water (which is turning to steam) cannot escape fast enough. The internal pressure will fracture a piece like this that has not gone through a thermal drier. The schedule to fire this test brick was 150F/hr to 250 and hold 90, 200F/hr to 1640 no hold, 120F/hr to 1888 no hold. The fracture likely happened because the kiln schedule did not allocate enough hold time at 250°F or proceeded too fast to 1000°F. 250°F might sound like too high a temperature to do water smoking at because it is over boiling point, but in practice it does work in industrial kilns and driers with good airflow (which this kiln does not have).
Glossary |
Bisque
Potters and some manufacturers fire ceramic ware twice, once to prepare it for glazing (call bisquit firing) and the second time to melt the glaze onto it. |
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