Understanding & Preventing Project Explosions

What: Clay project explosions, such as that pictured at right, can be devastating to students and cause damage to other projects in the kiln.

Why: Sculptures can explode if there is too much moisture left inside.

• This particular sculpture was several inches thick, and although it dried on a wire shelf for over a month and had a vent hole to encourage moisture on the interior to escape the piece, moisture was still trapped inside in other parts.

• Sometimes, no matter how long a clay piece is sitting out to dry, the ambient moisture in the environment can be enough moisture to cause cracking and, sometimes, explosions, if the piece is heated up too quickly.

How to Prevent Explosions:

• Always feel pieces before loading them to determine their moisture level and temperature. If a piece feels cold, there is still moisture inside. As it can be sometimes hard to tell if a piece is cold with one's fingers, a good tip is to hold up the project to one's cheek instead to determine the temperature

• It is a good idea to candle a load of greenware before bisque firing and to ramp up the kiln slowly during the bisque fire, especially if the pieces are thick. See Preheating/Candling.