Silicone Molding

How To Make A Silicone Mold

1. Making the Molds

Measure the RTV silicone Base into a disposable container that is approximately four times the volume of the rubber.  Accurately add the exact amount of Activator required.

2. Making the Molds

Thoroughly stir the mixture with a flat blade spatuala or with mechanical mixing. Be sure to scrape the sides and bottom of the container to ensure the correct ratio of Base to Activator. Stir slowly until a uniform color is achieved without streaks.

3. Deaerate Mixture

Place the mixed RTV silicone rubber into a deaeration chamber capable of 28 to 29 inches of mercury vacuum. Allow the rubber to expand and collapse back to its original volume. Maintain vacuum for an additional one to two minutes. Release vacuum and remove the container from the deaeration chamber.

4. Pour Over Released Pattern

The part to be duplicated should be coated with a mold release agent (MR-15 is recommended) to ensure easy separation. The part should be placed into a box that will contain the silicone rubber while it is a liquid. Slowly pour the mixed silicone rubber over the released pattern being careful to avoid the formation of air bubbles or entrapped air. Allow the rubber to flow around the part to a minimum depth of 3/8 to 1/2 inch.

5. Allow to Cure

Allow the rubber to vulcanize for 16 to 18 hours at room temperature (70°F). Lower temperatures and/or low humidity will cause the cure time to lengthen; conversely, higher temperatures and/or high humidity will cause the cure time to shorten.

6. De-Mold

Partially disassemble the mold box and remove the cured block of RTV silicone rubber. Carefully flex the mold to remove the original part.

7. Completed Mold with Pattern

The silicone mold is ready to be used with appropriate casting materials to duplicate the original pattern.

Silicone Molding Products

Clear #1011

Medium viscosity, ultra-clear resin that exhibits excellent air release properties and improved UV resistance. Our most widely used system, it is ideal wherever improved flow characteristics and UV resistance are required, such as protective coatings on pictures and labels. It is also an excellent system for coating bar tops.

Clear RBC-1047 Resin

The products listed in this chart constitute just some of the products in our standard line, additional products may be found in our Resources Section. In addition, samples are readily available upon request. If you cannot find what you are looking for, our technical staff can also work with you to create a custom formulation to meet your specific requirements. If you have any additional questions or require any samples, please fill out our Online Information Request Form and someone from our staff will get back to you right away.