The Best Industrial Polymers
Artists rely on polyester and polyurethane resins when they need to do clay modelling and casting. This resin is the best for that kind of work since they sure and form a hard cast. They can also come off as glass, and shine through when they have been sanded and buffed. You however need to know which one applies in a particular job. It is therefore important to find out more about their differences.
Polyester resins are the cheaper alternatives in the market. There must be a catalyst or accelerator for it to work as needed. They on the other hand give off a toxic odor, which forces an artist to wear a protective gas mask as long as they are casting. You also need to work in a properly ventilated studio. There must also be reinforcement in the form of a filler, like fiberglass. In future you can expect them to develop spider web-like cracks.
There is also the fact that polyester resins cure to a clear finish. There is however the danger of them yellowing out with time, when they are struck by UV light. They shall also be malleable for a short time, which needs the artist to work fast. They are too hard to use after ten minutes. They can be tricky to use due to their high and unpredictable shrinkage rate. IT is used to bond fiberglass fabrics into hard sheets.
Polyurethane resins, on the other hand, are more costly. They are however more versatile. They can be used in rubbers, plastics, inks, medicines, and more. They can take the abuse from chemicals, oils, grease, and abrasion better than others. They shall also not give off the toxic gases while casting.
You can get them in opaque and water clear resins. The casts they form shall have a lot of details and will not tear easily. You can use it to make plenty of plastic options, from the hardest to the smoothest. Since they can easily form bubbles, you need to work on them in a pressure pot or a vacuum chamber. They also respond only to special types of paint. This makes its choice of colors more limited than other options.
The only issue with polyurethane resin is the moisture sensitivity it has. It needs a dry climate for proper curing. If you work in a humid environment, you should make use of a dehumidifier. It is therefore good that they cure faster. You thus need to move fast in your working.
These are the things that make you realize that polyurethane resins are better for general mold making and casting works. They are thus preferred in a clay studio. Polyester works well for fiberglass fabrications.