Molding & Casting

Silicone Rubber Moulds

If made thick enough, silicone rubber molds are extremely versatile but don’t require a support material for the creation of a mother mold. Some characteristics of silicone rubber molds include but are not limited to:

There are generally two types of silicone rubber used in the molding process and they are referred to as tin-cure and platinum-cure. The major difference between the two is in the metal used to catalyze the respective rubber. In the case of tin-cure, tin is used to catalyze the rubber, and with platinum-cured, platinum is used.

Every rubber is subject to cure inhibition due to potential contaminants present on the surface of the object being molded. In general silicone rubber is sensitive to sulfur which is often found in a variety of modeling clays. In the case of Platinum-cure these rubbers are very sensitive to sulfur and in most cases will not cure at all if present. Tin-cure on the other hand does not have a problem if the model contains sulfur as long as the model is first sealed. In most cases, tin-cure rubbers will be significantly less expensive than their platinum-cure counterparts.

Shrinkage is a major difference between these two rubbers both long and short term. In general, Tin-cure rubbers will exhibit higher shrinkage over time when things like rubber, casting material, and mold configuration are taken into account. Library life is another important component to consider when choosing which rubber to work with. Tin-cure generally has a shorter library life when compared to Platinum-cure. When looking at Platinum-cure rubbers you want to think in decades for your library life whereas most Tin-cure rubbers are several years at best. Platinum-cure silicones are often used in historical preservation due to their extremely long library life.

Matrix Moulds

One of if not most common mold types. This process involves creating a thinner layer of rubber around the object and then encapsulating that in a harder material such as plaster or fiberglass. The end result creates a jacket-like effect. Of all mold types, matrix molds are said to be the most accurate. Some characteristics of matrix molds include but are not limited to:

Easier part ejection due to removable rubber sleeve. Being able to separate the rigid shell from the flexible sleeve aids in the removal of more complex parts.

Reparability is significantly enhanced due to the interchangeable nature of the parts.

Note: There are other types of molds including resin molds, polyurethane molds, collapsible core molds, and epoxy molds. Certain types of molds are passed depending on your industry, product, process, etc. Leave it up to Kemperle Industries for advice and suggestions on what type of mold best suits your application.

Fibreglass Moulds

Fiberglass molds are incredibly durable allowing them to sustain more abuse during the casting process.

When working with fiberglass certain safety measures are necessary to deploy to ensure the safety of those handling it. Adequate ventilation and the use of a respirator are amongst the most important of these measures. Some characteristics of fiberglass molds include but are not limited to:

High strength to weight ratio. These molds tend to be much lighter than traditional molds made of plaster. This gives you greater flexibility when working on a larger scale.