Resin Casting Using A Pressure Pot

Resin Casting Using A Pressure Pot

Posted by Matt Piggin & Nikki Michaels on 27th Oct 2020

Resin Casting Using A Pressure Pot

In today’s blog, we take a detour away from spray painting to discuss something a bit different: resin casting using a pressure pot.

Mainly associated with small-scale industrial and manufacturing prototypes (although it has a wide variety of applications), resin casting involves filling a mould with liquid synthetic resin, which hardens and creates a product or piece of equipment that can be used or sold. It can also be utilised in the production of things such as jewellery, small collectibles, and replacement parts like doorbell switches.

The first step with any resin casting is to mix your resin with your hardener and pour the liquid into your mould — which leads us to one of the biggest problems with the process in general. When you mix, air bubbles inevitably form within the resin. If these aren’t effectively dispersed, they show up in the final product and create unsightly defects in its appearance.

But there’s an easy way to ensure you end up with a clear, bubble-free cast. It’s the pressure pot.

As you can probably guess by the name (and as you’ll know if you’ve used a pressure pot for spray painting), pressure pots apply up to 80 pounds per square inch pressure to their contents, forcing out air bubbles and ensuring the result is smooth. In the case of spray painting, this results in flawless coatings and seamless finishes — and in resin casting, it results in pieces and products that are crystal-clear and free of air pockets or traps.

Pressure pots come in a variety of sizes that allow them to be used for resin castings of all scales and complexities. You can purchase a pot specifically for resin casting (in which case it will come with all the bits and pieces you need to safely cast), or you can swap out a couple of parts to quickly modify the pot you use for spray painting.

If you already have a pressure pot and want to use it for resin casting, you’ll need:

  • A specialist valve able to be set up to the maximum pressure of your pot. Between 60 and 80 psi is generally recommended for resin casting.
  • A ball valve that you can attach to the fluid outlet. This will be shut off throughout your casting activities and opened to release pressure.
  • The right hose to connect to your pressure pot fitting. A ¼-inch is typically perfect.

Watch The how to set up a pressure pot for casting video here

Watch The how to adjust the pressure valve for casting video here

Mix your resin and hardener, and pour them into your mould.

Replace the safety valve on your pressure pot with the specialist valve, attach the ball valve to the fluid outlet, and ensure your connecting hose is properly attached.

Put your casting(s) in the pot, and tighten the bolts to secure the lid. Set your safety valve to the correct psi, and switch on the compressor. When it reaches your desired psi, switch it off. It should hold at that pressure; this will display on the pressure gauge.

Leave your casting in the pot until the curing process is fully complete. This generally takes about 12 hours.

Post-curing, open the ball valve and allow the pressure to escape from the pot. Once pressure is released, it is safe to loosen the bolts, take off the lid, and remove your completed, air-bubble-free casting.

We have a selection of resin casting pressure pots at Millin. 

If you need help deciding which one’s right for you (or if you require assistance selecting the correct safety and ball valves to make your existing pot fit for casting), please don’t hesitate to contact me on 021434724 or at