Venting a Silicone Mold to Eliminate Bubbles In Casting


Jerry Ross, President of Ross Concepts in Dover, NJ, had to mold and cast a precise prototype of an LCD mounting platform.  The application called for low long term shrinkage in the mold and very high tensile strength in the finished casting which will have a wall thickness of about 1/8" (.32 cm).   Mr. Ross selected Mold Max® XLS, Shore 30A tin-catalyzed silicone that exhibits very low long-term shrinkage.  He selected TASK® 4 as the casting resin because of the low viscosity (abiity to flow), strength when cured, and low shrinkage.

This particular prototype design posed challenges in getting the casting resin to flow to critical mold areas.  Mr. Ross pre-planned to punch air vents into the cured XLS mold with brass tubing and an exacto knife.  The vents would allow air to escape and minimize bubble entrapment in the finished TASK® 4 casting.

The following sequence chronicles Mr. Ross's process in successfully reproducing this model using an advanced mold making technique.

Materials Used in this Tutorial

Step 1: Constructing Mold Box