Which Casting Material To Use?

Casting is an interesting art of reproducing a positive of the given model or figure from its negative mold. There are various methods of making casts that range from the simple to the most intricate depending on the shape, size and other details of the master.

Generally speaking, a cast is made by pouring, brushing or spraying the casting material either inside or over the mold. A variety of casting materials can be used depending on the mold, use of cast and the personal expertise of the artist.

Let’s take a look at some of the popular options like plaster casting, resin casting, rubber casting, etc.

• Plaster – Plaster is an inexpensive and versatile material that can be easily used to make top quality, highly detailed casts. Plaster casts display a bright white finish and are ideal for painting. They resist moisture too. However, plaster casts tend to break easily and bigger ones can get quite heavy.
• Resin –Different resins like polyester, epoxy and polyurethane can be used to make a wide range of plastic replicas. Polyester resin is used for molded reinforced fiber and composite products, but it is not safe to use. The casts are very hard, turn yellow soon and may break when dropped. Epoxy resin takes time to cure and is mostly used to coat finished artworks. Polyurethane resin casting is versatile and can even be used to make artistic jewelry. But it has a propensity for air bubbles and needs to be deaired properly.
• Latex rubber – This compound is quite durable and long-lasting and yet relatively inexpensive. It is used to make all kinds of flexible rubber items like toys, props and hollow articles. It is also exceptionally suitable for making gloves, masks and other thin skin products. Latex rubber is even used for creating special effects like wrinkles, scars, gashes and wounds for film and theatre. Proper storage is essential and latex should not be allowed to freeze.
• Silicone rubber – This is another versatile material that can be used for all types of mold making applications – be it giftware or figurines. Some variants are suitable for food molds, body molds, mask making and doll reborning while some find usage in prototype tooling and animatronics. Silicone rubber does not even require the use of a release agent.
• Simulated metal – The look and feel of various metal, stones or even wood can easily be created in a cast with the help of cold casting powders. The respective powder can be added to a resin binder prior to casting or even a thin coating can be dusted, brushed or sprayed on the cured resin cast.
• Concrete – Just like the above materials, a liquid mixture of concrete can be poured into the mold to make hard and durable casts. But the mold should be resistant to tearing and abrasions.

The author is a mold maker by profession. He has penned the article down to highlight the uses of latex rubber in mold making and casting.