A gas kiln's temperature varies depending on the type of ceramics being fired. Low-fire processes typically reach 1830°F - 1940°F (Cone 6-4). Mid-range stoneware fires around 2167°F - 2232°F (Cone 5-6). High-fire porcelain and stoneware can achieve temperatures of 2300°F - 2381°F (Cone 9-10), with specific temperatures determined by the desired pyrometric cone.
Ceramic kilns operate across a broad spectrum of temperatures, typically ranging from 1830°F (999°C) for low-fire bisque to 2381°F (1305°C) for high-fire stoneware and porcelain. The specific temperature depends on the clay body, glazes, and desired firing effects. Pyrometric cones help monitor and measure these crucial heat levels.
Electric kilns are highly versatile and commonly reach temperatures up to Cone 10, equivalent to around 2381 degrees Fahrenheit (1305 degrees Celsius). They are widely used for both bisque and glaze firings, offering precise temperature control and an oxidizing atmosphere. Many hobbyists and professional studios favor them for their reliability.
Raku kilns operate at much lower temperatures than high-fire kilns, typically reaching Cone 8 to Cone 6, which is approximately 1720°F to 1830°F (940°C to 999°C). The unique raku process involves quickly removing pieces while hot and placing them in reduction chambers, emphasizing the lower peak temperature.
Firing cones, or pyrometric cones, are small ceramic pyramids formulated to melt and bend at specific temperature and heatwork combinations. They provide a visual indicator of the kiln's thermal maturity, not just peak temperature. A bent cone signifies the ware has absorbed enough heatwork for the desired chemical and physical changes.
Different clay types require distinct temperature ranges for proper firing. Earthenware typically fires low, around Cone 6-4 (1830-1940°F). Stoneware is mid- to high-fire, Cone 6-10 (2232-2381°F), achieving vitrification. Porcelain also fires high, often Cone 8-10, for its characteristic translucent strength. Matching clay to temperature is vital.
Wood-fired kilns can reach exceptionally high temperatures, often exceeding Cone 10 (2381°F or 1305°C), and sometimes even higher. The intense heat, combined with the volatile ash and unique atmosphere created by burning wood, contributes to distinctive glaze and surface effects. Achieving these temperatures requires considerable skill and fuel management.
Modern pottery kilns, especially specialized high-temperature gas or electric models, can achieve temperatures exceeding Cone 10, potentially reaching up to Cone 12 or 13. This translates to roughly 2455°F to 2500°F (1346°C to 1370°C). Such extreme temperatures are used for very specific materials and research, pushing ceramic possibilities.
Kilns used for glass typically operate at significantly lower temperatures than pottery kilns. Glass fusing and slumping temperatures usually range from 1200°F to 1700°F (650°C to 927°C), depending on the specific glass type and desired effect. Pottery requires much higher heat to vitrify clay and mature glazes.
Bisque firing, the initial firing for ceramics, typically reaches a peak temperature between Cone 8 and Cone 4, which is approximately 1720°F to 1940°F (940°C to 1060°C). This temperature hardens the clay without fully vitrifying it, making the ware strong enough to handle and glaze, yet still porous.