Polyurethane or Silicone – Which Mold Rubber to Use?

Polyurethane and silicone rubbers are the most popular mold making materials because of their versatility and ease of use. So, which of the two options will actually suit a particular application?

There are a variety of mold making materials for capturing negative impressions of artworks and other models. The options range from the simple clay, wax and alginate to sophisticated materials like polyurethanes, latex rubber, silicone rubber, thermoset mold rubber and so on.

Each material comes with its own set of advantages and disadvantages. The choice will depend on various considerations that includes the material of the model, the choice of casting material and even the personal preference of the mold maker, to name a few.

Yet, it emerges that polyurethane mold rubber and silicone mold rubber are usually preferred by mold makers owing to different factors like the versatility of the materials, the inherent ease of use and also the durability of the molds.

So, let’s take a look at how an artist would choose between polyurethane rubber and silicone rubber to understand how these factors play out in reality:
  • Polyurethane mold rubber is a popular option for casting wax, plaster and especially concrete. Concrete casts are usually made in polyurethane rubber molds only as silicone may cause efflorescence in the castings. Silicone rubber is preferred when the artist has to go on to cast polyester, epoxy and polyurethane resins. In other words, silicone rubber is usually used for making a resin casting.
  • Generally, both polyurethane and silicone rubbers can be used on any model of any material without causing any damage. However, if the artist is making a body mold from a live human being, they have to use special skin safe silicone rubber only.
  • While the mold rubber itself will not damage an inanimate model, the release agent can definitely have an adverse effect on the surface. Therefore, in case the artist cannot or does not want to use a release agent, silicone rubber will be the material of choice since it does not stick to anything except itself. However, it follows that silicone rubber molds cannot be used for making silicone rubber casts!
  • Polyurethane rubbers are more economical than the highly expensive silicone mold rubbers. It is obvious that an artist will prefer the polyurethane variant whenever it is suitable.
  • The final choice will also be influenced by the dexterity of the artist. Many artists prefer to use a particular mold making material just because of the familiarity and comfort level with the same.

It is possible to play around with these factors depending on the circumstances too. For instance, polyurethane rubber molds can be used for making hundreds of plaster, wax and concrete molds while silicone molds are suitable for large quantity of resin castings without any distortions or damage. However, in case the artist requires only 10 to 20 resin cast parts, they may opt for polyurethane rubber molds since it is easier on the pocket. But using a release agent will become mandatory!

Handy Kits Available at EnvironMolds

A variety of mold making and life casting kits are featured on the EnvironMolds website. This serves as a quick and easy introduction to these specialized arts. The options are varied and interesting.

EnvironMolds offers an extensive range of mold making, casting and lifecasting kits that are especially handy for beginners. The kits contain all the required materials, supplies and tools for a one-time project.

For instance, the Latex EZ Casting kit has everything needed to create molds of a Trilobite fossil and a life-sized snail followed by a casting. Accordingly, it contains Kreemtex Liquid Premium Mold Making Rubber, CastRite Art Stone, Chavaunt clay, fossils, mixing cups, mixing sticks, brushes, cotton swab and fine cheesecloth. The materials are of studio quality; the quantity and size are suitable for the project on hand. It also comes with an illustrated instruction guide that demonstrates each and every step with full clarity and detail. The directions are easy to follow and the process becomes interesting and enjoyable.

The life casting kits are a complete delight as well. In fact, the company website http://www.artmolds.com features the largest collection of life casting kits available anywhere. There are various kit options for casting a baby's hand and foot, adult hands, faces, torso and even the full body. They are helpfully marked as beginner, experienced and advanced levels.

For instance, the Pro Hand EZ Cast Kit is perfectly suitable for serious life casters who want to turn this artistic hobby into a part-time business. This bestseller has actually been tested and approved by 60 members of the reputed Home Arts Magazine Club. Yet, even novices can use the kit to create museum-quality sculptures. It is also used by professionals to create hand castings for profit at various venues.

The beauty of the kits is that the user does not have to assemble all the nitty-gritty materials for making a mold, cast or life cast. The quantities are appropriate, thus eliminating guesswork while purchasing individual projects. Moreover, the user will also get an idea about what and how much to buy when working on similar projects in the future.