Vacuum Chamber

What is a Vacuum Chamber?

A vacuum chamber is specialized equipment that removes trapped air bubbles from mixed silicone by creating a negative-pressure environment, ensuring a flawless final product.

Why Are Air Bubbles the Enemy?

When Part A and Part B of silicone are mixed together, the stirring process inevitably introduces air into the material. These microscopic bubbles, if left untreated, cure right into the finished toy as tiny voids, pinholes, or weak spots. In a product that needs to be smooth, strong, and visually flawless, trapped air is unacceptable. The vacuum chamber is the tool that solves this problem.

This process is called degassing, and it is one of the most critical quality-control steps in fantasy toy manufacturing.

How Does Vacuum Degassing Work?

The freshly mixed silicone is placed inside the chamber in a container -- typically one much larger than the volume of silicone, because the material will expand dramatically during the process. The chamber is sealed, and a vacuum pump draws the air out, dropping the internal pressure far below atmospheric levels.

As the pressure drops, dissolved air in the silicone expands and rises to the surface. The silicone mixture visibly swells to 2 to 6 times its original volume as thousands of tiny bubbles rush upward and pop. Once the expansion peaks and the silicone collapses back to its original volume, the degassing is complete. The entire process typically takes 3 to 10 minutes depending on the batch size and silicone viscosity.

How Does It Compare to a Pressure Pot?

The vacuum chamber and the pressure pot both address air bubbles, but they take opposite approaches. The vacuum chamber removes bubbles before pouring by extracting them from the liquid silicone. The pressure pot compresses bubbles during curing to make them invisibly small. Many professional makers use both methods in sequence for the highest quality results.

Some makers prefer vacuum degassing alone, arguing that truly bubble-free silicone produces a more structurally consistent toy. Others rely primarily on pressure pots, especially for complex molds where pour speed matters and the silicone's pot life is limited.

What Should Buyers Look For?

A well-degassed toy has a completely smooth, uniform surface with no pinholes or tiny craters. If you see scattered pinpoint holes on a silicone toy's surface, it likely was not properly degassed or pressure-cured. This is one of the quality markers that separates professional indie makers from amateur operations. When a maker lists "vacuum degassed" in their process, they are telling you they invested in proper equipment and technique.