Mold Making
Historical Molds
Mold making is a crucial step in the lost wax process. It requires the capturing of detail in an artist's sculpture and being able to produce the same detail in a bronze casting. A hundred years ago, molds were made using plaster and gelatin. Unfortunately, gelatin molds did not have a very long shelf life and were also not very durable. Wax sticks to gelatin molds. Also, protein based gelatin molds will fall apart after a few uses. Additionally, they will develop actual mold such as Penicillium and Aspergillus. Furthermore, some molding materials like older polyurethane and silicone catalysts can include lead or other ingredients that can be hazardous. Algae based molds known as alginate also have a short shelf life as they are mostly made of water and will shrink as they dry.
Our Molds
Master Molds
The best quality molding material we have found is silicone rubber. Fortunately, we have a long standing relationship with Silicones, Inc. Their silicone rubber allows us to make master molds that are usable for over a decade with proper storage (depending on the complexity of the sculpture.) Also they are based in North Carolina and all of their products are made in the USA. Furthermore, Silicones, Inc customized their formula with feedback from us. As a result, we can ensure our molds are as accurate, durable, and versatile as possible for sculpture molding. With their help, our molds work well with a wide variety of clays and other sculpting materials.
Mold Accuracy
This silicone rubber is able to capture high levels of detail. Our specialists have the expertise to capture details so precise it even includes fingerprints. Silicones, Inc even has a formula that is gentle enough on human skin for medical applications and life casting. Specifically, this enables us to create bronze memorials of a loved one using a mold accurate to the fingerprint.
Mother Molds
After the rubber master mold is finished a protective mother mold is made. We use a plaster mother mold reinforced with natural fibers to create a sturdy outer shell. The plaster keeps the rubber in its shape without warping or flexing. Therefore, our natural fiber reinforced plaster helps create more accurate waxes. Also, it uses more sustainable and environmentally friendly materials.
Some mother molds are made using fiberglass and resin. Those require additional reinforcing to prevent flexing and warping. This is often achieved using PVC or metal piping. While they are often lighter than plaster molds they present more health hazards in the creation process. They are also less environmentally friendly and sustainable in practice.
Removing the Original
Once the molding process is complete, the finished mold is opened up and the original sculpture is removed. Because the rubber is closely applied in order to capture every detail, removing it often results in portions of clay sticking to the rubber. This does mean that an artist's original clay work will sustain some damage from the molding process.