Silicone Mold Manufacturing Methods for Soap, Candy, Cake & Ice Cubes

Customer Inquiry:

I’m a soaper (soap producer/molder) currently working with 12×15 wooden molds and desperately need to increase my output. So I do need a larger size.

Casco Bay Molding Response:

We injection mold silicone rubber, for advise on product development please follow this link: Product Development. The size of an injection molded silicone part is dictated by the size or tonnage of the molding machine (force machine has to keep mold closed) and the projected area (inches or cm squared) for the part.

With Silicone we try for a 1 to 2 tons (2 is safe) for every 1 inch squared of projected area.  Your 12×15=180 inches squared is a too much projected area for our 90 ton machine.

With a few flood gates (overflow areas in mold >> not recommended with liquid silicone rubber injection molding) we could get get close to a 90 inch squared part projected area. For example: 6×15=90 or 12×7.5=90 inches squared.

The more accepted manufacturing process for large projected area parts like Soap, Candy, Cake and Ice Cube Mold Manufacturing is compression molding. Compression molding is a more labor intensive process where HCR (High Consistency Rubber – pre-mixed one part silicone) is manually placed in the mold then the compression mold is closed for a relatively long cycle time, 3-10 minutes depending on part thickness.  The parts are removed and the extra silicone (known as flash) is trimmed from the part.  This labor intensive process is popular in lower wage countries.

My advise is to find a compression molder in your area or overseas and get them to quote a larger sheet style soap mold.  Perhaps you could work with other “soapers” to invest in a compression mold together?

Casco Bay Molding does Liquid Silicone Rubber Injection Molding which is better suited to cleaner – non-flash applications, like medical, where the silicone is not handled but is injected directly into the mold from a 55 gallon drum or 80lb kit (sheet rock buckets).


Andrew Powell

Liz Thornton