Fast cure resin bubbles like CRAZY

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CharlesHouse

Active Member
I purchased a 2 gallon two part resin and tried it today. I had a tiny amount of it that I put into an empty watch body. It bubbled so much and set promptly so that it was basically a large raised layer of bubbles above the watch face. I sanded it down but found that the bubbles went all the way to where I poured the liquid prior to it foaming. This is really troubling. It set too quickly to even consider putting in a chamber, and the foaming makes it seem like it would be dangerous to use on large molds.
 

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p00k1333

Well-Known Member
RPF PREMIUM MEMBER
The only time I had resin do that to me was when I used pecan shell flour to extend and lighten a cast. The pecan shell had moisture in it and began foaming instantly in the mixing cup, rising like a column of hardened bubbles. I later found out that I needed to dry it in an oven for several hours to make sure it was completely dry.

Is there a possibility of high humidity or even water in the watch body causing this?
 

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Kevin Gossett

Master Member
RPF PREMIUM MEMBER
Absolutely. Product settles as it sits on the shelf, so it needs to be shaken prior to use. Then you need to let it degas before mixing, to avoid the bubbles
 

Duncanator

Sr Member
I think Pook1333 was on the right track. Your symptoms sound like moisture got into the resin causing it to foam.
 

PoopaPapaPalps

Master Member
RPF PREMIUM MEMBER
Moisture/humidity and heat are most likely the culprits in cases like these. I don't know if you're using Smooth-On products, but Onyx is notorious for me for doing this. To the point where it even emits steam, I've experienced.

Beyond looking out for that, shaking absolutely helps. That's why it's on the jugs to say "SHAKE WELL BEFORE USING". When I work with those materials, I take that to heart; shake vigorously for a few minutes and let settle for a couple hours before I start casting.

Those two tricks solved my problems. Another thing to take into account is amount of material. The more you use; the more vigorous the reaction. So it's always a good idea to go in small doses.
 

robn1

Master Member
I've had this happen too, because of humidity. The resin might be fine once or twice if it's a new batch, but the opened bottles will eventually become contaminated with moisture. I've had thin slush cast parts blow up like rising bread, and cure like a hard sponge. Smooth-On Task 2 and 3, and Onyx have all done this. BJB 1630 and Freeman Repo One are the only resins I've used that had no reaction, because they're made for use in alginate molds so they're more resistant to moisture. Unfortunately those two are not suitable for most of my needs. The only way I can avoid resin foaming is with a pressure pot. If I have to make a part that can't go into the pot I use epoxy.
 

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sjanish

Sr Member
RPF PREMIUM MEMBER
I've had luck using old resin, think 1+ year old, if I put parts A and B in a vac chamber first. Shake each one real good and then put it in the a vac chamber. IIRC leave part B until the bubbling slows.. Part A will never stop bubbling.

I've read that doing this can ruin your resin, but my result before vac'ing were a foamy mess so I had nothing to lose. After vac'ing the resin performed like normal.

I should mention the resin was Smooth-On Smooth Cast 305.
 
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