exploding resin?

ManicMan

ManicMan

Lord
Okay.. I'm afraid I've misplaced my bloody camera right now (ugh) but... I did a couple of bits of resin casting the other day and I think I must have screwed up the mixing (this resin doesn't like to take paint and mixing white and clear doesn't make it very easy to see how it's mixed... need to figure out where my old resin pigments are). Appeared to cast fine though, just took a bit longer to dry and a couple of smaller bits are still a bit tacky so probebly won't dry. No problem.

now.. one of the bits which was fine, I painted, no problems. I then glued the back to a bit of wood cause it's part of something.. then.. a few hours later, I noticed it appeared to be bulging a bit.. wasn't like that when I was painting it.

It's been a few days since then, and now.. it's bulging more and feels more 'solid' in the bulge.. worse case, I can just remove this and bin it, though the bulging isn't too out of place.. it's just.. huh.. never seen resin do that to me before. If it keeps expanding... does resin explode? that might be fun.

It's a polyurethane resin (50:50 by weight) but.. is it reacting to something? the glue? (current glue is gorilla super-glue which is ethyl-2-cynnoacrylate I believe), was the not quite mixed (it appears) resin meaning it's still giving off some gas, but because it has no where to go (I guess the surface is too cured) it's just building up as it's still trying to set?
 
I think it's stopped expanding now but.. boy, it's very bulged. I did wonder about leaving it as that's find for a weird old building BUT, it's bulged at the back too so doesn't sit flat. I made up a new piece and I'll try to take a photo tomorrow showing the difference.

all I can think is it was taking a very long time to cure and because the surface did cure first, it was just releasing gasses (I know resin releases heat and gas as it cures but I'm not sure what gas) which just got trapped. I'm gonna have to have some fun and cut it to see.
 
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bulge copy vs non-bulge version (which is currently being painted up). Not the best shot but I think you can see how bulging that got. It was flat at first ^_^;
 
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I would say clearly Gas. Outside is pretty strong but crunchy to cut, and inside it must have taken much longer to cure so it kept going, with some gas building up as it couldn't escape.

I'm not up on the chemicals used in this resin, but a fair guess would be Carbon di-oxide as it would be a polyol mixed with isocyanate to make the polyurethane.. but chemicals is fair from my field ^_^

If it wasn't for the fact of how bulged the back was, I would have probably left it as is. you get that kinda damaged with old buildings ^_^
 
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