Wednesday, 8 April 2015

Safe Cooling Speeds

Almost everywhere you read that you should not open your kiln to cool it. But we know that the kiln cools progressively slower as it nears room temperatures. So how do we safely cool the kiln at rates the glass can cope with.

Some advocate directing a fan at the closed kiln on the grounds that air movement will cool the kiln faster than still air will. Yes, but at a negligible rate due to the insulation properties of the the kiln.

It is much safer to program a sensible cooling rate all the way to room temperature from 370C. This allows you to open any viewing ports knowing that any rapid cooling will be counteracted by the controller switching on the heat. Upon hearing that power input, you can close the ports partially until the kiln cools a bit more.

At lower temperatures, you can open the lid or door. The controller will operate as before warning you of too rapid cooling, so you can reduce the opening until more air is required.