How to Use a Pressure Pot

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    • #15740 Reply
      Amy Griffith
      Guest

      Hello!

      I am new to using resin and have had some success in casting using your super clear product but still have an issue with bubbles. I have a space heater, heat gun, mix slowly and deploy all of the other suggestions posted. I would like to try a pressure pot but I am struggling to find clear and specific instructions on how to use it with a resin that requires the length of cure time as an epoxy resin such as the super clear. Most of the resources I have found online are for castings with the use a resins with a relatively short cure time. I am casting jewelry (using moulds mostly purchased from you 🙂

      So my questions are:

      – Do you leave the mould in the pressure pot with the compressor running for the full cure time or just a portion of the cure time but left in the pressure pot?

      – I have a very large compressor and it is very loud. Can a smaller one be used with say a 2 1/2 gallon pressure pot?

      – I am a little confused about the use of both a vacuum, compressor and pressure pot – do I need all 3 for best results and if so, can you point me in the right direction for instructions?

      – I read on your forum that the moulds will be fine in the pressure pot – is that the case for plastic and silicon moulds for jewelry?

    • #15745 Reply
      Katherine Swift
      Keymaster

      Hi Amy,

      I’m sorry to hear you are experiencing bubbles with the super clear resin. Have you tried warming up the resin first? That is what works best for me. I show how to do that here: https://youtu.be/ugQSgVIP2Uk

      As for a pressure pot, the resin has to be under pressure the entire time while it is curing. In the case of the super clear resin, this will need to be 12 hours. The compressor may or may not need to be running the entire time. If you have a good seal on your pot, I would expect you would not need it running.

      Pressure casting makes the bubbles so small that you can’t see them. Vacuum casting pulls the bubbles to the surface to try to get them to pop. In your case, you will want to pressure cast. Vacuum casting works great for silicone, but I find with epoxy resin it makes ‘beer foam’ on the top of the castings.

      I have not pressure cast with plastic molds, but haven’t had a problem pressure casting silicone molds.

      If you want to get a pressure pot, I recommend Grainger. Their pots are a little more expensive, but I think they are better made and safer.

      • #80599 Reply
        Matt
        Guest

        Are there any resins that cant be used in a pressure pot?

    • #32470 Reply
      Amanda
      Guest

      Hi Katherine
      I read the abive with interest.
      Can you post a link to the Grainger model you can recommend, and the compressor?
      And, will the pressure pot require many modifications – if so, what?
      Many thanks in advance!
      Amanda

    • #59455 Reply
      Maegan Rush
      Guest

      Sill question but can you use something like an Instant Pot or a canning pressure cooker or do you have to have a specific type or pressure pot?

      • #80600 Reply
        Matt
        Guest

        You need to use either a paint pressure pot that you can alter, or purchase one specifically for it. Manufacturers are just now starting to make them specifically for casting, in the past you had to alter the one made for commercial painting. Google resin pressure pot. You will need an air compressor and the pot.

      • #82352 Reply
        Manuel
        Guest

        I know it’s been over two weeks but you do need to use a pressure pot specifically designed for resin casting or, take a paint pot and make the necessary modifications.
        A regular cooking pot will not withstand the pressures necessary to cast resin. There are some videos of people taking regular cooking pressure pots and using them for resin casting. They haven’t been hurt…yet. A stove top pressure cooker or Instapot is rated to handle 10 to 15 psi. To get bubble free resin castings you need 40 to 60, depending on the resin manufacturer. I would not want to be around a pot that has been subjected up to 5 times it’s rated PSI when it blows.

        • #93281 Reply
          Ryan Elliott
          Guest

          False. Pressure cookers hold up to 25psi. Plenty for resin.

          • #93290 Reply
            Scott A White
            Guest

            A pressure cooker used as a pressure pot is a potential bomb waiting to go off.
            I’ve been making props for years and the rule for resin is if you want to go cheap you buy a Harbor Freight pressure pot. The stories of pressure cookers failing , and spraying an area with shrapnel is scary, and that’s while cooking in them. The failures when they are used with compressed air are much worse. Trust me… I,ve blown a couple up!

    • #84434 Reply
      Douglas Davies
      Guest

      Hi,
      The resin im using heats up and gets hot. Can i still use it in a pressure pot?

      X Doug

    • #88517 Reply
      K. Stackpole
      Guest

      I like making the resin pyramids and I am wondering if you can do several layers of resin in the pressure pot, one layer at a time, because I like to layer my pyramids. Also how well does it work with dried flowers and such embedded in the resin. One more question, if you put more than one mold with resin in the pot do they have to have the same amount of resin? Thank you so much for your time, I am finding it very hard to find a whole lot of information on this subject

    • #92985 Reply
      Veda
      Guest

      Reposting this question!!! I want to know this too!!

      I like making the resin pyramids and I am wondering if you can do several layers of resin in the pressure pot, one layer at a time, because I like to layer my pyramids. Also how well does it work with dried flowers and such embedded in the resin. One more question, if you put more than one mold with resin in the pot do they have to have the same amount of resin? Thank you so much for your time, I am finding it very hard to find a whole lot of information on this subject

    • #93374 Reply
      Keith
      Guest

      Can you use a pressure pot to remove bubbles from resin prior to pouring the resin into the mold?

      • #93376 Reply
        Katherine Swift
        Keymaster

        Hi Keith,

        A pressure pot is meant to reduce the bubble size of resin already in a mold. The resin should be kept under pressure during the entire curing time.

        You can try using a vacuum chamber to remove the bubbles, but it’s been my experience that it takes the bubbles to the top and makes foam (like beer).

      • #95754 Reply
        RQ
        Guest

        For a pressure pot to be effective, the resin should stay in (under pressure) the entire curing time. This will ensure that the air that has been compressed (Positive pressure = microscopic bubbles, too small to see) doesn’t re-expand and put those bubble back into your casting.

        Vacuum pressure will make the air expand/bubbles grow (negative pressure = bubbles expand). This allows the air to expand, move up and be popped, thereby creating a bubble free pour (yes, you should release the vacuum after a minute or so, to allow (with help) the bubbles to pop.

        I’m going to postulate that if you are using pressure, you want the bubbles gone, but it will be in the working during curing process, (casting pen blanks, Jewelry stuff, e.g. small stuff); if you need to remove the bubbles, but you can’t put the entire piece into a pressure pot (Haven’t found a pressure pot to handle a river table yet), then ‘de-gassing’ your resin in a vacuum chamber will allow you to remove a lot of the air before you pour. (large(r) pours = $$)

        Although I haven’t tried it myself, but everything I’ve said here (from what I’ve read) also applies to silicone mold making as well. That’s on my experiment list for next week! (Going to try that next so I don’t hand over a small fortune in molds)

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