Refers to the practice of slow-heating a kiln during early stages to give mechanically-bound water a chance to escape.
The practice of slow-firing ware through the critical temperature surrounding the boiling point of water. This is done in situations where a drier is not available, it prevents cracking and explosions associated with steam trying to vent out of ware that is not completely dry. When ware has a thick cross section, such as for sculptural pieces, a kiln might be candled for days or a week. For typical gas firings of functional ware, it is common to candle overnight on very low heat and then continue the firing normally the next day.
Industry fires much faster than potters and have found the water smoking period of a firing can be conducted much faster than was previously thought possible. Ware can be heated to past the boiling point and soaked there for a shorter time and fired quickly after that.
Designing a good kiln firing schedule for your ware is a very important, and often overlooked factor for obtained successful firings.
All types of ceramic are fired in a kiln to cement particles together to produce a hard and water and temperature resistant product.