Translations:AY Honors/Ceramics/Answer Key/79/en

Properly called Crystalline, this is a special effects glaze made primarily of particles of zinc oxide and silica mixed with water. It is applied to the ceramic piece in a thick paste. Crystalline glaze is extremely runny at peak temperatures, a clay pedestal and glaze catch dish used for each item to prevent the glaze from running onto the kiln shelves. While at peak temperature (around 2350 degrees F), a chemical reaction between the zinc oxide and the silica forms seed crystals from which the crystal will eventually mature. After the chemical reaction is stimulated, the kiln is cooled 200 degrees below the peak temperature. The temperature is then held for 5 hours to allow the crystals to grow to the desired size. This is called the soak cycle. Once this cycle is completed, the kiln is turned off, and the crystal growth period is complete.