How do you make bronze sculptures?

Have you ever looked at a bronze sculpture and wondered how they make it, and why bronze sculptures are more expensive than those made from plaster or clay?

The lost wax process has been used for thousands of years, and little has changed from what artisans did then to today.

The sculptor usually makes the sculpture in clay or other soft medium. A silicon rubber mould is then made over the original artwork. A hard plaster mould surrounds the soft silicon. The original clay is then removed and wax is poured into the silicon mould. This is usually around 3mm thick.

The wax version is then removed from the mould. The silicone mould is then put aside and the wax copy is used for the next stage of the process. This is the “wax chasing” stage. The wax will have marks on it from where the mould came together, so this needs to be removed, together with any other imperfections. A hot metal tool is used.

The wax copy is then “sprued” or “gated” which means adding pieces of wax onto it that look like branches or straws with cups at the top of them. This is to enable the hot bronze to be eventually be poured into the mould and hot gases and air to escape.

The sprued wax copy is then dipped into a slurry of colloidal silica and zircon, then into a refractory sand-like stucco which gives it a hard cement like look.
This waste mould is built up in layers, over a few days.

The wax is then melted out of this waste mould and the mould is fired to 1,000 degrees. Bronze is then poured into the shell waste mould. The bronze liquid is at about 1,200 degrees!

When that has cooled, the shell is smashed away to reveal the bronze sculpture with the sprued sections still attached. It’s pretty rough with lots of jagged edges, so it needs to be cleaned up. This “metal chasing” stage uses grinding and welding tools.

Now we have a bronze version of the original sculpture which needs to be coloured. Regular paint is not used. We now enter the “patina” stage, which involves applying oxidizing solutions, blow torch, and lots of elbow grease.

And finally, we have a stunning sculpture that you see on display.

To see the patina stage, have a look at this video:

The entire lost wax process described above can be seen in this video:

To see the finished product, come and visit us at Sydney Pop Up Gallery.

We have works by 8 sculptors and 4 painters. There's a great variety of styles, so there's something to suit everyone's tastes.

We're open every Wednesday, Friday, Saturday and Sunday from 10am to 4pm.

You'll find us at Garibaldi Village Square, 37 Alexandra Street, Hunters Hill.