What is Kiln? A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay into pottery, tiles, and bricks. Kiln Prices In South Africa? R18,000R20,000. Kiln. R15,000R25,000.