Designs For Casting
Unlike ‘ lost pattern ‘, permanent pattern, or ‘indirect’ casting, offers the founder the liberty to select from a diverse range of construction and modelling materials when patternmaking. The technique does so due to two further stages in the founding process.
Reproduction moulding is the first of the stages and is a general term that covers rubber, plaster, and plastic moulding materials. They can then make a mirror image or a ‘negative image’ impression of the original model.
Wax patternmaking is the second of these new stages and consists of making and taking out a wax variant of the artist’s model from its reproduction mould. Then the waxy model is used in the investing process rather than the client’s original. This use safeguards the original artwork throughout the entire casting cycle from any harm or injury. This is why the method is called ‘permanent pattern’, or in the French language: ‘Plâtres de travail’ literally translated as working plasters or plasters of work.
The permanent pattern method has a goodly number of mattering implications.
The founder can create the sculpture’s maquette, or master pattern, is free to use any and every – stable and suitable – material, like plaster, clay, metal, ceramic, etc. Even if the founder chooses a soft one, like wax, to make the master pattern, the original will be kept whole since any copy made or needed will come out of the reproduction mould rather than it.
This non-reliance on the original, and instead on a reproduction mould, allows the modeller to reproduce replicas of the client’s design without involving it and, in the process, putting it in harm’s way. If any failure in casting has occurred, it will be simple and easy to create a fourth or fifth pattern and re-do the process without needing a new sculpture.
Casting an edition is another bonus of the process: allowing many casts of the same artwork at the client’s behest.
Indirect or ‘permanent pattern’ casting has been an almost industry-wide standard for professional casting for quite a while – even though casting errors rarely occur. Founders, however, would rather the minimal expense of a reproduction mould rather than risking the artist’s model entirely – ensuring their position, you could say.
They are also a less nerve-wracking affair, judging from the mistake-allowing feature covered before. And yet another good quality, the original can be kept as a reference for quality assurance throughout the entire model-making cycle, especially in the chasing stage.
It is pretty easy to see that the permanent pattern technique allows the founder to try new things, new modelling materials, and new foundry techniques. So, the following sections will look at some common materials and methods used by founders and foundries.