Pressure Pot

What is a Pressure Pot?

A pressure pot is a sealed chamber that uses compressed air pressure to force trapped bubbles in silicone down to invisible size during the curing process.

How Does Pressure Curing Remove Bubbles?

While a vacuum chamber removes air bubbles before pouring, a pressure pot takes the opposite strategy: it leaves the bubbles in place but crushes them into oblivion. Once the silicone has been poured into the mold, the entire mold is placed inside the pressure pot. The pot is sealed and pressurized to 60 PSI or higher using a standard air compressor. Under that pressure, any air trapped in the silicone compresses to a size too small to see or feel.

The mold stays under pressure for the entire curing duration -- typically 4 to 8 hours or overnight, depending on the silicone system.

Why Does Pressure Curing Work?

Physics makes this elegantly simple. At 60 PSI, a bubble shrinks to roughly one-fifth its original size. At higher pressures, even less. A bubble that would have been a visible pinhole on the toy's surface becomes a microscopic void that is structurally and cosmetically irrelevant. When the pot is depressurized after curing, the silicone has already hardened around the compressed bubbles, locking them in their tiny state permanently.

This is especially effective for complex molds with deep channels, intricate textures, or thin-walled sections where air tends to get trapped during pouring. Even if the maker's pouring technique is perfect, certain mold geometries inevitably trap small pockets of air. The pressure pot is insurance against those unavoidable pockets.

What Equipment Do Makers Use?

Most indie makers use modified paint pressure pots or purpose-built casting pressure vessels. The key requirements are a reliable seal, a pressure-rated gauge, a safety release valve, and enough internal volume to fit the mold with clearance. Makers often build custom lids with proper fittings to handle the demands of daily production use.

The air compressor must be capable of reaching and maintaining the target pressure for the full cure cycle. A slow leak in the seal or a compressor that cycles off overnight can result in incomplete pressure curing and visible bubbles in the finished toy.

How Does It Compare to a Vacuum Chamber?

Professional-grade operations often use both tools in sequence: degassing the liquid silicone in a vacuum chamber first, then pressure-curing the poured mold in a pressure pot. This belt-and-suspenders approach produces the cleanest, most bubble-free results. Budget-conscious indie makers sometimes choose one or the other based on their production volume and mold complexity.

When shopping for fantasy toys, a maker who mentions pressure-pot curing in their process is signaling attention to quality at the manufacturing level.