Block Mold - Multi-Part | Page 5
Pour the material high, slowly and in a narrow stream, starting from the corner of the mold box, or mold, letting the material flow freely into the box or mold cavity. Because the pour is in a high narrow stream, trapped air can better escape from the downward stream of silicone rubber before it enters the mold box. This method will usually not introduce any new bubbles into the vacuumed material.
The mold box is removed after the silicone rubber has cured. It will feel firm to the touch without being tacky.
The two halves of the silicone mold are spread open to reveal the model.
At the bottom end of the mold a large pour hole is cut into the rubber using a mold knife or an Exacto knife
Figure 33 shows both mold halfs with a semicircular cut on the bottom of each. When the halves are joined together this will become a round opening so that the casting material may easily be poured to fill the mold.
Figure 34 shows a finishing technique. We will use KastEZ Resin for the casting material. By spraying the inside of the silicone mold with acrylic paint it will adhere to the surface of the cure casting creating a pre-made finish. In this example we use black acrylic paint to establish a dark undercoat which will help create a metallic look when the final finishes are applied to the casting.
The two halfs of the mold are joined and held together using mold straps.