Should I use a pressure pot or vacuum chamber for casting?
Pressure Pot for Casting
A pressure pot works by applying air pressure (typically 40-60 PSI) to shrink bubbles until they dissolve into the resin. This is ideal for clear casts, molds with fine details, and projects where bubble-free results are critical.
You pour your resin into the mold, place it in the pot, seal it, and pressurize. The resin cures under pressure, so bubbles never form or become visible.
Pressure pots are common for pen blanks, jewelry, and small castings. They require an air compressor and a pot rated for the pressure.
- Best for bubble-free castings.
- Works during curing.
- Needs 40-60 PSI.
- Requires an air compressor.
Vacuum Chamber for Degassing
A vacuum chamber removes air from mixed resin or silicone before you pour it. It pulls bubbles to the surface and pops them, but it doesn't work once the resin is in the mold.
Vacuum chambers are essential for making bubble-free silicone molds and for degassing resin that will be poured into open molds. They don't help with closed molds or pressure casting.
Some crafters use both: vacuum the resin, then pour and cure under pressure for the best results.
Common mistakes
- Using a vacuum chamber on resin in a mold—it can cause the resin to overflow and make a mess.
- Thinking a pressure pot removes bubbles; it only compresses them so they're invisible.
- Skipping a pressure pot for detailed molds and then wondering why bubbles appear on the surface.
