BRONZE CASTING PROCESS
Stage 1: Sculpting the original
After the commission is agreed between Charlie and the client, an original clay sculpture is made of the subject
Stage 2: Mouldmaking
Once complete, the original clay is taken to the bronze casting foundry where a rubber mould is taken. This picks up all the detail of the original and consists of different sections, each contained in their own plaster jacket
Stage 3: Wax Casting & Chasing
The two halves of the rubber mould are sperated, and the original plasticine portrait is then removed from inside. Then the mould is put together, and wax poured in to give an even thin coating of wax a quarter of an inch thick. After the wax has cooled, the rubber mould is seperated, leaving the wax cast from each half. Then the wax is removed from the rubber mould and seamlines removed. Charlie then works the original wax to add make any further adjustments to the sculpture and sign the work.
Stage 4: Runners & Risers
Wax sprues are added to the sculpture and a large cup is attached at one end which will receive the molten bronze when poured. The placement of the sprues allows the molten bronze to flow through these areas once the pour is made
Stage 5: Ceramic Shell
A secondary mould is taken around the wax, by dipping the wax in a liquid binder solution, called "slurry". In addition to the outside coat, the wax is also filled in with a ceramic core to allow the final cast to be hollow. After this, a very fine silica sand is coated onto the slurry, creating a ceramic shell around the wax.
Stage 6: Metal Casting
The ceramic shell is then placed in a large oven, upside down. Once the oven heats up, the wax melts and pours out through the risers, leaving the thin negative space where the original sculpture occupied between the two layers of ceramic shell. This is inspected and once again heated up and placed in the pouring pit. Bronze ingots are heated up to 1200 degrees Celsius and poured into the hollow space between the ceramic shell and allowed to cool and solidify.
Stage 7: Fettling
The shell material is hammered away, revealing the bronze casting underneath. It is then sand blasted to remove any remaining shell material from inside and outside the bronze.
Stage 8: Welding & Chasing
All sections of the bronze are carefully aligned and welded together, and any defects removed and chased to ensure the bronze sculpture looks the same as the original artwork. The bronze sculpture is then chased to remove any sign of welding.
Stage 9: Patination
The desired colour for the sculpture is achieved by applying gradual layers of heat (blowtorch) and chemicals. After this, the sculpture is sealed with a wax coat and lacquer to protect the finish.
Stage 10: Finished Bronze Sculpture
The sculpture is complete and ready to be sent to its new home!