Metal Casting : Courses : Foundry : Loss Wax Technique

The ’loss wax’ technique:


derived from the  process of removing the pattern, made of wax, from the ceramic investment mould. De-waxing is the term used to describe the process wax of removal from the mould.

Once the ceramic shell mould is completed and dry the process of removing the wax pattern can be undertaken. 
The wax is melted out of the mould creating a void,  ready to be filled by another casting  material, glass or metal. The mould should be placed on a heat proof perforated surface with a collecting pan/tray placed underneath. Its a good idea to make sure that there is a quantity of solid wax in the pan/ tray as this keeps the wax that is to be melted out of the ceramic mould from catching fire while its being collected.

Heat is focused on the open aperture of the mould and connecting architecture of the mould, to rid the mould of the wax pattern.  Heat is distributed evenly around  the aperture of the mould so that within a few seconds  wax will be seen  evacuating out of the base of the mould into a collecting tray. Once this occurs attention can be directed to the main pattern body, directing the heat up from the base of  the mould,  effectively melting concentric sections of wax out of the mould until the top is reached. The process continues until it can be see that there is no further wax leaving the ceramic mould.

The mould will most usually catch fire, this is residual wax wicking in the mould body and will eventually burn itself out. At this point the ceramic shell mould will be at its most delicate and they require handling with care. Choices on continued processing depend upon the application of the mould and material to be cast.