Porcelain Glaze Firing with Partial Carbonization using Wood Charcoal

Abstract

This research has developed a new firing technique using wood charcoal which does not produce smoke vapors during firing. There is only solid carbon element as the source of carbon atom. Place the charcoal on the bottom of a closed refractory box saggar for firing porcelain teacups using white glaze and then burn at 1250 ^oC for 30 minutes. Unique, beautiful teacup products consisting of black clay body at the base due to carbon are obtained. X-ray diffraction tests revealed a small amount of graphite crystals were found to be present in the main crystalline components of quartz and mullite. However, at the mouth of the teacup is white, similar to that of normal firing in an oxidative atmosphere. It was also found that the glaze around the mouth of the teacup is pale pink, which is thought to be a result of the formation of almandine crystals, which contain iron oxides. Moreover, the effect on some areas of the glaze near the base is reduced until forms bubbles while firing. When it cools down, if it is partially polished off the glaze bubbles, it will reveal a shiny and black surface.