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(Above photo - Italian Bronze Nude Female Harp Player Classical Art made via the lost wax process )

Lost wax has been the most popular method of casting bronze over the centuries. It is an elaborate method of producing bronze statues of all shapes and sizes. Bronze lost wax is called so since bronze is cast around a wax model. After melting down the wax, one comes up with a mold in which he or she pours the molten bronze. The process takes place in the following simple steps.

1. Creating the Mold

(Above photo - Large bronze fountain )

The first step involves the creation of the original wax (or another material) model. Then, a mold of the model is made from fiberglass or plaster. Usually, the mold would consist of two or more parts. Later on, the parts can be put together before casting the bronze. Long additional parts may require separate molds to create them.

2. Pouring Wax

After finishing the mold, the artist pours molten wax into it. He or she swirls the wax until an even coating of at least 3mm thick is achieved. Or, one could pour the molten wax into the mold and let it sit until it solidifies. The idea is to achieve a wax thickness of a certain thickness.

3. Removing Wax

(Above photo - Bronze Statue Britannia - Roman Goddess Britain )

Once the wax has adequately solidified, it is removed from the original mold. The artist may create multiple wax copies of the original mold, depending on his or her needs.

4. Chasing

Chasing is the process of removing marks showing flashing or parting lines where the pieces of mold were enjoined. All imperfections are removed by dressing the wax. The artists then heats and attaches the different mold pieces.

5. Spruing

(Above photo - Art Deco Biba girl statue in bronze made via lost wax )

The artists sprues the wax to create a treelike structure that allows wax to freely flow through. Also, it is meant to release any air that could be trapped inside the mold. Whether the sprue is hollow or not, it will be melted out in the end.

6. Slurry

Once the wax copy is sprued, it is dipped into a silica slurry followed by an even grained crystalline silica. This creates a ceramic shell that’s left to dry. The artist pours additional layers of silica until it reaches a thickness of at least half an inch.

7. Burnout and Testing

(Above photo - Antique Bronze Atlas figure statue )

When the shell is heated in a kiln, the silica hardens while the wax melts away. The molten wax can be burnt up or collected and reused. Space builds up inside the shell in place of the wax that has been burnt out.

8. Testing and Pouring

(Above photo - Art Deco biba bronze girl after Max Leverrier )

After the ceramic shell has cooled, water is poured through it to test the vent and feeder tubes. The artist patches any cracks using refractory paste. He or she tests the thickness of the shell by drilling and patching holes. After reheating the shell, the artist pours into it, molten bronze. The shell is then left to cool.

9. Release and Metal Chasing

To release the shell, an artist may use a hammer or sandblast. He or she cuts off the sprues and reworks the sculpture to remove any signs of casting. Any pits have to be filled out and polished. That is done until the sculpture is ready.

As you can see, bronze lost wax is an elaborate method whose steps an artist needs to follow strictly.