Make multiple reproductions of your sculpture in bronze. Bronze sculptures are usually made using the lost-wax method. Lost-wax bronze casting is an ancient art form that is practised in much the same way as it was thousands of years ago. Making bronze sculptures with this method requires much time, resources and assistance. However, the process is very rewarding since it allows artists to create sturdy reproductions of their sculptures.
- Skill level:
Things you need
- Finished sculpture
- Polyurethane or silicone rubber
- Ceramic resin or plaster/sand mixture
- Natural gas furnace
- Molten bronze
- Dental tools
- Soldering irons
- Hand-held buffing machine
- Ferric nitrate, cupric nitrate or sulphurated potash
Coat the entire sculpture with polyurethane or silicone rubber using a brush. Allow the rubber to harden. This will create a negative reproduction of the sculpture in the rubber. Cut the rubber reproduction into two pieces so that it can be removed from the sculpture.
Reattach the reproduction by placing the two pieces together and tying them with some twine. Fill a can full of heated liquid wax, and then pour the wax into the reproduction. Allow some of the wax to coat the walls of the reproduction, then pour the remainder back into the can. Repeat the process around three times, using cooler wax each time.
Separate the rubber mould into two pieces again, and remove the positive wax mould of the sculpture. Check the sculpture for imperfections and correct them by using dental tools and heated soldering irons to smooth out the surface. Attach wax sticks to the sculpture with a soldering iron to allow gas to escape the sculpture when it is heated later.
Dip the reproduction into a vat of ceramic resin or plaster/sand mixture repeatedly to create a hard shell around it capable of containing molten bronze. Hang the ceramic shell with the wax still inside to dry.
Heat the ceramic shells in a kiln and melt away the wax. Heat bronze to its melting point in a gas furnace. Pour molten bronze into the ceramic shells. Allow to cool for one hour.
Use chisels and hammers to remove the ceramic shell from the now solidified bronze. Smooth and polish the bronze with a hand-held buffing machine.
Apply colour to the bronze sculpture by brushing or spraying chemicals onto it without heat. Chemicals commonly used are ferric nitrate, cupric nitrate or sulphurated potash. Each type of chemical produces a different colour on the bronze.
Tips and warnings
- Molten bronze is very hot and should only be poured by trained professionals.
- Kiln operation should also be done only by those with proper training.
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