Creating a rubber mold makes replication of small relief sculptures simple and fast once the mold is completed. Rubber takes fine detail well. Making a rubber mold is easy, but can take time. Rubber molds are a good choice for small items. The flexibility of rubber molds simplifies unmolding the finished product. If you are not confident making your own molds, you can approach custom molding manufacturers for help. Rubber doesn't require mixing which means there is no waste. Other mold compounds include silicone, usually a 2 part compound that is very good for miniatures and alginate temporary mold compound which is well-suited to body casting.
Materials Needed to Make a Rubber Mold
How to Make a Rubber Mold From a Small Relief Sculpture
A rubber mold is made by brushing 10 or more thin layers of rubber compound over the original. The rubber will easily pull away from many different surfaces, but cannot be used on metal.
The sculpture needs to be held in place on a non-metallic slick surface. A heavy piece of cardboard covered with plastic wrap will work. Secure the plastic wrap to the cardboard with tape. Punch a few small holes through the wrap and the board where the sculpture will be to provide air so the rubber will cure properly. Use double stick tape to hold the sculpture in place. As can be seen in the pictures below, small sculptures can be grouped to make just one mold.
Use an inexpensive paint brush to apply the rubber compound in a thin, even layer over the sculpture. For deep details, it's very important not to fill them with rubber. Thick layers will not cure properly, causing the mold to fail. Store the paint brush in a plastic sandwich bag between layers of rubber. The rubber needs to dry between layers, but not completely. It will change color as it dries, and should still be slightly sticky when the next layer is applied. Drying time depends on temperature, and varies. At least 10 layers should be enough, check that any edges have enough rubber to feel a little squishy.
The finished mold needs to completely cure for a minimum of 3 days before being used. Before removing from the original, make a plaster support to keep the mold from twisting and sagging when it is used.
Make a Plaster Mold Support
Follow the directions on the plaster to make a thick plaster paste. Sprinkle the mold with a little talcum powder as mold release. Cover the mold with just enough plaster to fill the voids and support the mold, smooth it to sit level when it is turned over. Allow the plaster to set and remove the original and the mold until the plaster is completely cured.
Simply place the rubber mold in the plaster support, and fill with the chosen material. Some possible materials include plaster, clay, and wax. Wax has a wonderful translucent quality.
Though it will take a few days to get to a finished mold, molds are easy to make and a great way to reproduce items easily.
