A kiln is a special oven or furnace that reaches extremely high temperatures, far hotter than any kitchen oven, used to permanently harden clay, fire pottery, or process materials like bricks and cement.

When a potter shapes a bowl or vase from soft clay, it remains fragile and would dissolve in water. But after firing it in a kiln at temperatures often exceeding 1,800 degrees Fahrenheit, the clay transforms through a chemical change into hard, waterproof ceramic that can last for centuries. Ancient civilizations discovered this process thousands of years ago, and archaeologists still dig up pottery from kilns that fired 5,000 years ago.

Kilns come in many sizes. A small studio kiln might fit in a garage for an artist making mugs and plates. Industrial kilns can be enormous buildings that fire thousands of bricks at once for construction. Traditional pottery kilns were wood-fired and took days to heat and cool, while modern electric kilns let artists control the temperature precisely.

Beyond pottery, kilns also dry lumber, roast coffee beans, or process materials that need intense, controlled heat to transform into something stronger and more permanent.