Polyester Epoxy Urethane and resin-casting
For many centuries, the traditional material used to cast sculptures was bronze. Through industrialization, techniques were developed that facilitated casting in a variety of metal alloys such as iron, steel, stainless steel, aluminum, etc.
The emergence of plastics during the last century gave rise to the development of resins which provided a less expensive, durable alternative to traditional metal casting.
During the 1970’s I was fortunate to be one of the pioneers in the application of polyester and epoxy resins for sculpture casting in Cape Town.
These resins can be moulded in much the same way as traditional waxes; by painting swilling and in the case of small items by filling the mould. Large sculptures would have glass fiber cloth or mat, laminated into the resin to reinforce it. By this means excellent strength to weight ratios are achieved so that these castings weigh a fraction of a metal counterpart and are economical to transport and erect.
Metal powders can be added to the surface layers. The surface can then be abraded to expose the metal which will allow it to be patinated by traditional means. By adding pigment to the resin any color can be achieved. Metallic finishes and artificial patinas can also be added to the finished castings. Some sculptors imitate the patination process on non-metallic sculpture with the use of paints oils, waxes and pigments.
It is worth considering the viability of using resin to cast with, since unlike bronze it has no commercial scrap metal value. This is particularly so for outdoor art that is on public display which is especially vulnerable to scrap metal theft. In these instances, it is preferable to simply cast the piece out of resin using a rubber mould. Then, if a problem should occur with a resin piece, we simply cast another one.