Why do clay pieces have to be dry before they are fired in the kiln?

When clay is bone dry, it is pale and feels warm and dry to the touch. To prevent your ware from exploding in the kiln, it needs to be bone dry before it is fired. During a preheat the kiln needs to stay below 212F, so the water evaporates off before the firing schedule starts.

What happens when wet clay gets heated too quickly?

Chemically Combined Water Is Driven Off Clay can be characterized as being one molecule of alumina and two molecules of silica bonded with two molecules of water. Even after the atmospheric water is gone, the clay still contains some 14 percent of chemically bonded water by weight.

What happens if kiln gets wet?

If the kiln gets wet and then freezes, the water will expand when it turns to ice and can dam- age the brick and electronic components on your controller.

Can wet clay go in the kiln?

You can put slightly wet pottery in a kiln, provided you set it at a low heat for several hours. This is called candling and is a way of pre-heating the kiln before firing. Candling dries the clay out completely before the firing schedule starts, and prevents pottery exploding.

How do you fire clay in a kiln?

THERE ARE THREE COMMON WAYS TO FIRE AN ELECTRIC KILN. By manually turning the kiln on and up, and watching the cones inside the kiln through a peephole to determine when to turn the kiln off. By manually turning the kiln on and up, and using jr cones in a kiln sitter to turn off the kiln when it reaches temperature.

Do you glaze before firing?

Glazing Pottery is mainly done after the first firing. This first round of firing is called bisque firing and changes the clay permanently making it much harder but still porous enough to absorb the glazes.

Does clay shrink as it dries when fired?

Clay shrinks both in drying and in firing. Different clay bodies shrink at different rates which can be as little as 4\%, or as much as 15\% for some clay bodies. We also found through out after years of firing that even with the same clay body, shrinkage can vary 1-2\% from batch to batch.