Bronze Casting – The lost wax process
When pieces of Fine Art are made in bronze each piece, although taken from a mould usually, begins its life as a sculpture by the artist. Then a mould is made of this using a silicone rubber. Once the mould is made, which can vary in time due to the size and shape of the piece and whether the mould needs a fibreglass casing to help it hold its shape (usually for larger pieces), a wax is made by pouring hot wax into the mould and allowing it to cool. The wax is then worked by hand to clear it of any defects or vents from the pouring. Once the wax is made a pouring system will be attached to the piece, different foundries use different methods here. The wax and pouring system will be coated with a ceramic based coating, a few layers are necessary, and then fired to burn away the wax and harden the coating. A shell (negative) of the sculpture is created as the wax burns out the ceramic mould. The furnace is heated and the Bronze melted in a crucible. The molten Bronze is then poured into the ceramic shells and allowed to cool.
Watch a pour - http://tinyurl.com/76gbpxh