Lost Wax casting

The idea here is to create a version of the desired shape in wax which is encased in a ceramic. The whole thing is then heated so that the wax melts leaving the void into which the metal is poured.

There are two main ways in which the wax can be created. Most common for small parts like door furniture and so on where you might want multiple copies is for a flexible rubber mould to be formed around the prototype, which is then used for making waxes. These in turn are stuck together into a “tree” which is coated with successive layers of ceramic until a mould is created thick enough to withstand the heat and weight of the molten metal. The metal is poured in and after cooling the ceramic case knocked off to reveal the metal castings.

For one-off work like sculpture, a multi-part mould is taken off the original, reassembled as a hollow shell, into which successive layers of wax are poured. The middle part is then filled with sand, the mould taken off, and ceramic built up on the outside as before. Heat the whole thing, lose the wax, and fill the cavity with metal.

For an account of the process on a fairly large scale Cellini’s account of casting his statue of Perseus is a good read, always remembering that he was never one to understate his achievements! While our own work can’t claim the same provenance, the process used is much the same.

The pictures, which link to relevant projects, show: 

(top) A part of a wreath reproduced for a war memorial

(upper middle) The detail on a carved table leg cast hollow in bronze.

(lower niddle) A re-created sconce, the delicacy and detail demanding the lost-wax process.

(bottom) Cast from nature, a part of a 1.2m long doorhandle cast from a branch.