Degassing

What is Degassing?

The vacuum process of removing trapped air bubbles from freshly mixed liquid silicone before it is poured into a mold.

Why Are Air Bubbles a Problem?

When Part A and Part B of platinum-cure silicone are mixed together — whether by hand stirring or mechanical mixing — the process inevitably introduces thousands of tiny air bubbles into the liquid. If these bubbles remain in the silicone when it is poured into the production mold and allowed to cure, they become permanent voids trapped inside the finished toy. Surface bubbles create visible pinholes and craters. Internal bubbles create weak spots where the silicone is thinner and more likely to tear under stress. A toy riddled with uncollapsed air bubbles looks pitted, feels rough, and has compromised structural integrity — making degassing one of the most critical steps in the entire manufacturing process.

How Does the Vacuum Chamber Work?

Degassing is performed using a vacuum chamber — an airtight container connected to a vacuum pump. The freshly mixed silicone is placed inside the chamber in its mixing container, and the pump draws out the air, dropping internal pressure to near-zero. As pressure drops, the trapped air bubbles expand dramatically — the silicone volume can swell to 2 to 6 times its original size as the bubbles grow and race to the surface. Once the bubbles reach the surface and pop, the silicone collapses back down to its original volume, now free of trapped air. The entire process typically takes 3 to 8 minutes, depending on the volume of silicone and the power of the pump.

Why Is Timing Critical for Degassing?

Degassing must happen within the silicone's pot life — the narrow working window between mixing and the onset of gelling. If the maker spends too long degassing, the silicone begins to thicken and set before it can be poured into the mold, ruining the entire batch. This time pressure is why professional makers invest in powerful, high-CFM vacuum pumps that can pull full vacuum quickly. A hobbyist-grade pump that takes 15 minutes to reach full vacuum is useless with a silicone that has a 20-minute pot life, because the maker still needs time to pour after degassing. Speed and efficiency at this stage directly determine the quality of the finished product.

What Is Degassing vs. Pressure Potting?

Degassing and pressure potting are two different solutions to the same air bubble problem. Degassing removes the bubbles before pouring by expanding them in a vacuum until they escape. Pressure potting compresses the bubbles during curing by applying 60+ PSI of positive pressure, shrinking them to invisible size. Many professional makers use both: degassing the mixed silicone first, then curing the filled mold inside a pressure pot for maximum bubble-free results. The choice between methods depends on equipment, silicone formulation, and the maker's workflow preferences. Either way, the goal is the same — a flawless, void-free surface on the finished toy. At LustMonster, proper degassing is a non-negotiable step in producing the smooth, pristine finishes collectors expect.