Stone is a reductive artistic process, once you start to chip, there is no going back. So the Maquette is used to keep the chisel on track… More on that in my next section on blocking out the marble statue. Up to this point, months have been invested working on the design and emotion of the smaller Maquette. And so in order to preserve the value of all the work, a plaster casting has been made and then a clay copy has been pressed or poured. More months of effort.
A statue of this size (two thirds life) needs weeks to dry before it can be fired. If there is any residual moisture left in the statue, it will surely crack as the water is vaporized and steam pressure snaps the clay apart.
In fact, there is no practical way to fully dry your clay piece outside of the kiln. The “green ware” will always retain the ambient moisture that is all around us suspended in the air. There is no escaping the relative humidity in the air you breath.
With this in mind, when programming your electric kiln, ensure you hold the temperature below the boiling point (several degrees below for safety) until all the remaining moisture has evaporated… technically know as “candling”
My project contains over a hundred pounds of dry clay… and so I’ve decided to candle for 24 hours… better safe then sorry.
Also, the Pieta varies in its thickness.. Averaging half an inch… with this in mind, I have chosen to low fire the clay… only to a ‘bisque’ level. This is to prevent further splits and cracks.
Clay shrinks as it dries… the amount is dependent on the clay body, but up 10 percent is possible. As the clay shrinks, cracks may appear (as they did in my Pieta) This is easily repaired before firing…. Simply press more clay into the crack, let dry and continue to add and again let dry more clay until the crack finally stays sealed.
Fired clay continues to shrink as the temperature increases during the firing process… again, depending on the clay body, this could be an additional 10%.
If your statue cracked while it air dried… it will certainly crack during high fire.
So if you have any suspicions… do not ‘high’ fire. The low fire bisque does not significantly shrink… and so, for your first piece… Bisque Fire Only… don’t risk it…
After firing, you will have a permanent statue to work with, and will also be able to make additional pieces to sell, and help keep the lights on in your studio.