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Can Casting Resin be thinned before use

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  • Can Casting Resin be thinned before use

    Hello, I was wondering if anyone who uses casting resins regularly knows whether if it can be thinned just before use so that it can get into ALL little sections of molds and then cure hard without any issues? If so what is BEST used as a thinner? I use alumilite products mainly. I don`t have a pressure tank yet.

  • #2
    Originally posted by george View Post
    Hello, I was wondering if anyone who uses casting resins regularly knows whether if it can be thinned just before use so that it can get into ALL little sections of molds and then cure hard without any issues? If so what is BEST used as a thinner? I use alumilite products mainly. I don`t have a pressure tank yet.
    I have never tried to cut polyurethane casting resin. I always use it neat, George. I will cut an epoxy casting resin with a high grade (plenty of MEK) lacquer thinner.

    You really got to get that work under pressure as it changes state -- that's the best way to defeat those pesky little air-bubbles that mare the finish of the casting.






    In the interim, you should coat the cavities with a dusted on application of either talc or corn starch right after you spray on the part-release. The powder will help wick the resin into those tight spaces within the tools cavity that otherwise would entrap bubbles.


    Get a pressure pot and sin no more!

    "... well, that takes care of Jorgenson's theory!"

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    • #3
      Hello
      Thanks for the lessons. Just to make sure: 1) Spray mold release into mold, 2) Apply talk powder to mold 3) Use Mek Lacquer thinner IS MEK a brand OR specific version of thinner??? 4) MUST have pressure pot for Very Good finish.

      What is the operating pressure for the pots? Also how long of a time in the pot and then out of the molds?

      Thanks again
      George

      Comment


      • #4
        Originally posted by george View Post
        Hello
        Thanks for the lessons. Just to make sure: 1) Spray mold release into mold, 2) Apply talk powder to mold 3) Use Mek Lacquer thinner IS MEK a brand OR specific version of thinner??? 4) MUST have pressure pot for Very Good finish.

        What is the operating pressure for the pots? Also how long of a time in the pot and then out of the molds?

        Thanks again
        George
        Methyl Ethyl Ketone (MEK) is an ingredient in most commercially available 'lacquer thinners'. The more, the better. You can even cut epoxy with MEK neat.

        Yeah, spray in the part-release (we're not making a mold at this stage of the game, George. We're making parts!!!!!) into the tool cavities. The gooey part-release will adhere the powder. Sprinkle a healthy amount of talc or corn starch into the cavities of the open tool halves (make sure to keep your legs crossed, George, as I hear that talc will give you vaginal cancer!); close the halves; shake and pound them on the table to get the powder onto all cavity surfaces; open the tool; and dump the remaining powder on the nicest rug in the house; close the tool; arrange strongbacks, and pour your catalyzed resin.

        At room temperature I de-mold in about twenty-minutes -- that's for the 'normal' cure RS-3 ALUMILITE resin, by the way. Stay away from the slow-cure stuff as it never seems to get past the 'green' stage of hardness. You must get the work under pressure while it's still in the liquid state. You only drop the pressure back to ambient once the resin has transitioned to a solid state.

        I take the work down to one-atmosphere. That's 15psig or 30psia. Or, for you godless European types, 2 bar.

        David
        "... well, that takes care of Jorgenson's theory!"

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        • #5
          Again Thanks for the follow up lessons. Got to go to Home Depot for thinner and look for a Cheap pressure pot. Up here in Canada we are Cold and Cheap.

          Thanks again
          George

          P.S did you see my other questions reg. your OLD torpedo launchers I posted a few days ago?

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          • #6
            Originally posted by george View Post
            Again Thanks for the follow up lessons. Got to go to Home Depot for thinner and look for a Cheap pressure pot. Up here in Canada we are Cold and Cheap.

            Thanks again
            George

            P.S did you see my other questions reg. your OLD torpedo launchers I posted a few days ago?
            If you have Harbor Freight, then you can get the pressure pots there.

            Oh, yeah, thanks for reminding me. It's too cold now to trek to the shed -- I'll do it tomorrow and get those measurements for you, George.

            David
            "... well, that takes care of Jorgenson's theory!"

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            • #7
              That`s Great, Thank You

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