How to Make Rubber Molds
Mold-making, or the imprinting of a model into a mold form from which copies of the model can be made, is not just a process for the professionals. Rubber molds are fairly simple to make, with a little practice. With a rubber mold, you can make copies of existing objects and your own sculptures for props, home decor or play. This article covers one-piece rubber molds, but you can also make two- or three-piece molds with silicone rubber. To make your own rubber mold, complete the following directions.
Things You'll Need
- Latex gloves
- Goggles
- Protected workspace with forced ventilation
- Sculpey or plasticine clay
- Wooden molding box
- Silicone RTV rubber and catalyst
- Stirring spoons and mixing cups
Instructions
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1
Find or create a template object to make a one-part mold from. One-part molds are most useful for one-sided objects like masks and decorative prop surfaces. You can use an existing object or sculpt your own from Sculpey or plasticine clay. On a protected work surface in a well-ventilated room, set an open-top box that is about the size of your object, or at least big enough to house it. Lay your template object face up in the box.
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2
Mix together a small amount of silicone RTV rubber into a cup or bowl, following the directions on your particular package. When mixed properly, the rubber should be a pale-colored version of the catalyst color. Using a spoon, spread a thin coat of silicone rubber over your template object. Let the object dry completely, for at least an hour.
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3
Mix up a larger amount of silicone RTV rubber in a cup or bowl and pour it directly into the box, covering your template object completely. Make sure that the rubber is at least 1/2 inch above the surface of your template object. Let the silicone rubber dry for at least 12 hours before moving on to the next step.
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Turn over or disassemble the box so that you can remove the template object from the silicone RTV rubber mold. Take the mold out carefully, and do not crush any part of it. The mold is now ready for casting, which can be done with polyester casting resin or other materials.
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Tips & Warnings
If you are making a two-part mold, pour the silicone RTV rubber into the box first and press the object into it, then cover the rest of the object with rubber once the initial rubber dries. Take the box apart and separate the halves of the mold, then carve a hole into the bottom through which to pour casting material. Strap the mold halves back together to begin casting.
Always work in a well-protected environment, with a good amount of ventilation. Always wear latex gloves and safety goggles when working with silicone RTV rubber as it can be toxic. When casting, make sure that you are aware of the toxicity of the materials you are working with.
