Lost Wax Casting

The handle is removed and the bottoms of the cups are opened to allow the wax a way out, then the art is placed into the kiln which is powered by natural gas.  The hand crafted kiln has three floors to save the wax that is melted out of the art.  The first floor, the hearth, is made of sloping channeled stone which allows the wax to drain.  The hearth, the very bottom of the kiln is sloped to the center where a three inch hole allows the wax to flow into the catch pan.  We collect the wax and recycle it to the beginning of the process.  When the shell starts in the kiln it is fired to 1600 degrees.  It bonds the ceramic sand and slurry material into a solid that is close to becoming glass.  It takes 45 minutes to get the wax out completely.  Then it will fire for another two hours. The shell is at its strongest point when it is 1600 degrees.  At 1800 degrees it is pushed past its point of strength and is now closer to glass then ceramic. 

Once the de-waxed shells come out of the kiln they will be left to cool. Then our staff will be able to fill the shells with water to check for stress cracks and rinse any carbon out.  The stress cracks come from the wax expanding before the shell is at its strongest point.  Then the shell cracks will be filled, applying a brick mortar for strength.  This is the safety net if we were to break the shell or have bronze leak out.  We would have to start all over again with the mold and wax pouring, so this is the last chance to fix possible problems to obtain a perfect casting.