What is the main function of a kiln in ceramics?

A kiln is a specialised high-temperature oven used in ceramics. Its main function is to harden clay by firing it at temperatures that permanently transform the clay body. During firing, water is driven out and the silicate particles in the clay fuse together in a process called sintering, converting the soft, fragile dried clay into a hard, durable ceramic material.

Clay sourcing refers to the process of obtaining raw clay from natural deposits, which happens before the kiln is ever used. Colour mixing is a painting or glazing activity that does not describe the kiln's primary purpose. Surface glazing is a finishing technique where a glassy coating is applied to pottery - while a kiln is used to melt the glaze in a separate firing, the kiln's main function remains the hardening of the clay body itself, since without that initial firing the object would simply crumble.