Moulds are required across many industries and for many different purposes. Lots of different materials are suitable for creating moulds, and each has their benefits and drawbacks. Here is a quick guide to the different types, and their uses.
Silicones are formed of silicon and oxygen. Carbon and hydrogen complete the chemical composition and result in an extremely stable and non-reactive product. This union of atoms creates a material that can be poured into a mould and cured into a solid. When properly cured, silicone rubber has low thermal conductivity, low viscosity, high flexibility, and an extremely high tear strength. A range of curing options are available, and these can be tailored to different needs. Different types of curing will affect heat-resistance, although a general characteristic of all silicone rubbers is that they have a long life expectancy.
Like silicone rubber, polyurethane is part of the elastomer family. Elastomers have high viscosity. This means that the layers of the fluid hold together when poured, resulting in a dense, syrup-like liquid. As the viscosity of polyurethane rubber is lower than silicone rubber, this enables greater movement of air, and therefore a reduced risk of bubbles. Structurally, this makes polyurethane rubber an ideal choice for hard graft casting, such as concrete. However, polyurethane rubber is sensitive to moisture whilst sill in its liquid form, so care needs to be taken regarding both storage and application.
Natural Latex is seeing a surge in popularity since it occurs in nature. Natural Latex is obtained from Hevea Brasilliensis otherwise known as the rubber tree. In the 21st century, latex has a significant role to play in mould making. Supplied prevulcanised it requires no mixing or additives other than pigments.
Nature created latex to protect the delicate tissues of plants, and synthetic latex carries this characteristic into the industrial arena. It is formidable, highly tear resistant, yet thin enough to capture vivid textural detail. The main consideration with latex is that it takes several coatings, and this means that it can take time to create a latex mould.
Vinyl compounds are PVC resins that are solid at room temperature but can be easily heated into a liquid. It has the unusual advantage of being a moulding material that can be used many times. Vinyl compounds have a low melting point of 140oC, and it takes around an hour for them to set to room temperature, so they are a handy and cost-effective day-to-day solution for a wide range of moulding requirements.
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