Introduction
Under a somewhat wide definition, kilns have been around for roughly 20,000 years, with the oldest known pottery dating back to the ancient Near East¹ Modern kilns turn clay into food-safe and usable ceramics without heating sources directly touching the samples. The controlled heating environments can reach temperatures upwards of 2500°F (1371°C) – necessary to dehydrate the clay, vitrify feldspars inside the claybody and melt glazes onto ceramics. Bisque firing – a temperature range of 1623-2048°F (884-1120°C) – turns the clay into a frail and dehydrated ceramic in which the feldspar in the claybody has not yet melted to seal the surface. At this point, the ceramic inversion has taken place, clay is transformed to ‘ceramic’ and water is heated from the porous clay so that it can accept glaze easily. Following this process, the now-ceramic material can absorb glaze to make the product safe to eat and drink from after firing. Kilns heat up varying clay and ceramic samples in order to create objects (used to eat, drink, hold water, etc.) that cannot be achieved by other heating methods.²