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Full Version: Has My Resin "gone South?"
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Well, after what seems like forever, I opened up my Smooth-On white liquid plastic to mix up some casting material for a couple of parts. No sooner had I started to mix parts A and B but they started to cloud up (almost as if the reaction was starting to "kick" already). After I poured the mixed liquid plastic into my molds, it started to foam and spit! I actually took a step back in surprise!!

Does this exuberant chemical reaction mean that my resin is no more good? There is A LOT of liquid in both bottles and I'd rather not have to replace it all but, if it's shot, it's shot.

(fyi, the mixing cups were brand new and unused and the molds had never been used before either, so contamination there is unlikely)

Wadda' ya' think, gang; has my resin gone south?
I had a bad batch once from Smooth On. The resin bubbled and quickly cured in some areas to a brittle state, and never cured in others. I pitched both bottles entirely.
Thanks for sharing your experience, Del. Your end results sound exactly like what I'm seeing now. What's crazy to me is that a year ago I was able to use this resin perfectly with no such incident. Maybe it did just go bad over time or something. I hate to throw out so much unused material, but if it's worthless ... well, then it's worthless. <sigh> Oh well, I guess once I get new resin I'll just need to cast more often and not let this stuff sit around so long.

<fingers crossed that my supply of 2-part RTV mold material also hasn't turned!>
The 2 part resins usually has a shelf life, if not used by a certain time will get "spoiled".
It sounds to me like water got into your resin. How dry is the place you have been storing it, and how tightly were the containers sealed? All it takes is being some place moist, a garage when its been raining outside a lot, a basement. If you have a vaccume chamber you can try and degass the seperate parts before mixing, that can help draw some moisture out. And casting your parts in a pressure chamber will help compress the foaming.
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