Is there a way around investing in a vacuum pump and vacuum chamber?

Article courtesy of Smooth-On, Inc.

Although a vacuum pump and chamber will make your life easier if you are making silicone molds on a regular basis, it is a lot of money to spend on equipment. Some of our mold makers who do not own vacuum equipment claim that the following method works well to minimize bubbles in their finished mold:

  1. Mix a small batch of silicone to apply a "detail coat" to the model, using a similar stippling technique for making the first layer of a brush-on mold.
  2. Optional: Use a can of compressed air to pop any bubbles still remaining on the model surface.
  3. Mix the remaining silicone required to make the pour mold, then slowly pour off-model into the lowest point of the mold box, allowing the silicone to seek its own level. Pouring in a thin stream from a height of 2-3 feet allows entrapped air bubbles to elongate and break while pouring.

This FAQ article is offered as a guideline and offers possible solutions to problems encountered during mold making and casting. No warranty is implied and it is up to the end user to determine suitability for any specific application. Always refer to the provided Technical Bulletins (TB) & Safety Data Sheets (SDS) before using any material. A small scale test is suggested to determine suitability of any recommendation before trying on a larger scale for any application.