A kitchen pressure cooker is not safe or effective for resin casting. Pressure cookers max out around 10 to 15 PSI, while resin casting typically requires 60 PSI or higher for bubble-free results. Beyond the pressure gap, cookers are designed to contain steam, not compressed air, which creates a real explosion risk if you try to repurpose one.
Why Resin Casting Needs Pressure
When you mix and pour resin, tiny air bubbles get trapped throughout the liquid. Left alone, these bubbles cure right where they are, leaving cloudy spots, pinholes, and weak points in your finished piece. Pressure casting solves this by compressing those bubbles so small they become invisible to the naked eye.
The physics behind this follows a simple principle: when you increase the pressure above a liquid, gas dissolves into the liquid rather than forming bubbles. Think of an unopened soda bottle. The carbon dioxide stays dissolved as long as the cap keeps pressure on the liquid. Pop the cap, the pressure drops, and bubbles rush out. In resin casting, you’re doing the reverse. You seal the poured resin inside a pressurized vessel and force those air pockets to shrink and dissolve into the resin. The resin then cures around those microscopic or dissolved gas pockets, locking them in place so they never expand back to visible size. For this to work well, manufacturers recommend setting your pressure pot to at least 60 PSI, with results improving the closer you get to 100 PSI.
Why a Pressure Cooker Falls Short
Kitchen pressure cookers operate at roughly 10 to 15 PSI. That’s enough to raise the boiling point of water for faster cooking, but it’s nowhere near the 60 to 100 PSI range needed to crush resin bubbles into invisibility. At 15 PSI, bubbles shrink slightly but remain visible in the cured piece, especially in clear castings where every flaw shows.
The bigger problem is safety. Pressure cookers are engineered to contain steam generated by boiling water. Their lids, gaskets, and safety valves are all rated for that specific use case. Pumping compressed air from a compressor into a vessel designed for steam introduces forces the cooker was never tested against. The safety valves on a pressure cooker will vent long before you reach useful casting pressure, and if those valves fail or get blocked, the lid can blow off violently. Pressure cooker failures already cause injuries from steam alone. Adding compressed air to a vessel not rated for it raises the stakes considerably.
What a Proper Pressure Pot Looks Like
Dedicated pressure pots for resin casting are built as compressed air vessels, not steam containers. They typically handle 60 to 80 PSI as a working range, with safety margins above that. Many hobbyists convert paint pressure pots (the kind used for spray painting) into resin casting chambers. These conversions are straightforward because paint pots already have an air inlet fitting and are designed to hold compressed air.
A basic conversion involves removing the internal paint pickup tube, sealing any unused ports with bolts and rubber washers, and connecting the pot to an air compressor with a regulator. You need pipe thread sealant on every connection and a pressure gauge you trust. The key difference from a kitchen cooker is that these pots are manufactured and pressure-rated for exactly this kind of use. Look for vessels that carry markings indicating they’ve been tested to hold compressed air at the pressures you plan to use.
A decent paint pot conversion runs between $80 and $200 depending on size, plus the cost of a compressor capable of delivering 60 PSI or more. That’s a fraction of the cost of a purpose-built resin pressure chamber, and it performs just as well for small to medium castings like dice, jewelry, and figurines.
Pressure Pot vs. Vacuum Chamber
The other common tool for bubble removal is a vacuum chamber, which works in the opposite direction. Instead of compressing bubbles smaller, a vacuum pulls air out of the resin by lowering the pressure around it. The bubbles expand, rise to the surface, and pop.
For most resin casting, a pressure pot produces better results. Vacuum degassing causes the resin to foam up dramatically. You need a container with at least three times the headspace of your resin volume to prevent overflow. The process also only works before you pour the resin into a mold, so any new bubbles introduced during pouring remain in the final piece. Resins with short working times can start curing before you finish degassing.
Pressure casting, by contrast, happens after you pour. You mix your resin, pour it into the mold, place the mold in the pressure pot, seal it, and pressurize. The resin cures under pressure for the full demold time, keeping bubbles compressed throughout the entire process. For clear castings especially, pressure casting consistently produces the cleanest results.
Low-Cost Alternatives if You Have No Pressure Pot
If a pressure pot isn’t in your budget yet, a few techniques can reduce (though not eliminate) bubbles. Mixing resin slowly and deliberately introduces less air in the first place. Pouring in a thin stream from a height lets bubbles escape as the resin falls. A heat gun or small torch passed briefly over the surface of freshly poured resin pops surface bubbles by lowering the resin’s viscosity momentarily.
None of these methods match the results of pressure casting, particularly for thick pours or transparent pieces. But for opaque or pigmented resin work where small internal bubbles won’t be visible, careful technique alone can produce acceptable results. If you’re making clear dice, jewelry with embedded objects, or anything where optical clarity matters, a pressure pot is essentially required equipment. Just make sure it’s one actually built to hold compressed air.