Kiln Firing Chart

Firing converts ceramic work from weak greenware into a strong, durable permanent form. As the temperature in a kiln rises, many changes take place at different temperatures and understanding what happens during the firing can help you avoid problems with a variety of clay and glaze faults related to firing.

Kiln Firing Chart
Temp °C Temp °F Cone (approx) Incandescence Event
100 212 dark Water boils and converts to steam at 100°C. Trapped water causes clay to explode so keep the kiln below 100°C until all water has evaporated
200 392 Upon cooling, cristobalite, a crystalline form of silica found in all clay bodies, shrinks suddenly at 220°C. Fast cooling at this temperature causes ware to crack.
300–400 572–752 Between 480–700°C chemical water (“water smoke” is driven off.
500 932 black to dull red glow 573°C: Quartz inversion occurs where the quarts crystals changes from an alpha structure to a beta stricture. The inversion is reversed on cooling. This conversion creates stresses in the clay so temperature changes must be slow to avoid cracking the work.
600–800 1112–1472 022–016 dark red to dull red 300–800°C: Carbonaceous materials (Impurities in the clay along with paper, wax, etc.) burn out. The kiln requires ample air during this stage since after 800°C sintering begins and the clay surface begins to seal off, trapping unburned materials and sulfides, which can cause bloating and black coring.
900 1652 015–011 cherry red 800–900°C: The beginning of sintering, the stage where clay particles begin to cement themselves together to create a hard material called bisque.
1000–1100 1832_2012 015–03 red-orange to orange to yellow-orange 1100–1200°C: Mullite and cristobalite (Two types of silica) form as clay begins to convert to glass. Particles start melting together to form crystals, and materials shrink as they become more dense. Soaking (holding the end temperature) increases the amount of fused material and the amount of chemical action between the fluxes and the more refractory materials.
1200 2191 02–05 yellow End of earthenware (red clay) range
1300 2373 6-8 yellow-white to white Mid-fire range
1400 2552 9-14 white to brilliant white Stoneware range and  porcelain range.