How much does slow cooling of ceramic ware reduce the element life of a kiln?

Controlled cooling reduces element life--but the amount of wear varies depending on the kiln wall thickness and length of the controlled cooling. (A thick-walled kiln can often achieve the effects of slow cooling without even turning on the elements again after the cone bends.) Much of the wear on elements occurs when the elements struggle to reach high temperatures. The more they struggle, the faster they wear out. Controlled cooling is much easier on elements than that. To get the most out of your elements, begin the controlled cooling at the optimum temperature and no sooner, and maintain the controlled cooling for as short a period as necessary. You can determine the ideal slow cooling profile by testing glazes in a small kiln.