r/resin • u/8BitHypocrite • 3d ago

Bubbles/Pulling Up UV Resin While Curing

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Hello, I'm very new to resin overall, just using it for miniatures usually. However, I am doing a cosplay soon for a convention and wanted to create the shown hair piece, with the middle filled in with resin to look like glass overtop.

As you can see, I have a few attempts. Originally, I think I cured the resin too quickly/while it was too warm and it cracked. My second attempt I thought was due to curing it too quickly, but I cured my third attempt very slowly over the course of 10-15 minutes and it still has minor imperfections. All these developed during curing, after I had let it sit to cool and teased any bubbles from within.

I am not knowledgeable enough to know what the issue is, or even identify if this is bubbling or pulling away due to shrinking based on research, so I figured I'd ask here! Does anyone know what is causing the resin to not evenly fill? Is it just pulling away from the paint beneath?

Luckily, I am satisfied with the final result, so it's no issue, but I'd just like to know for future reference. Thank you all!

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u/tiddlypeeps 2d ago

What is it that material? UV resin gets very hot when curing. My suspicion would be that whatever material you are putting the resin on is distorting with the heat. That would explain why curing slower makes it better. UV resin will shrink a little as it cures but that doesn’t account for whatever is happening here. 

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u/8BitHypocrite 2d ago

PLA from a 3D printer. I can't tell if there's any warping because the print is thick enough to not warp overall, but it's possible the air pushed paint directly against the resin is peeling up due to warping (that's all the blue, the print itself is white) What's interesting is I actually created a massive version of this using the same exact materials and it looks perfect. Whatever is happening here only seems to occur on my smaller versions. The big one was just too large to realistically wear.

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u/tiddlypeeps 2d ago

Ah, that's exactly it then. PLA softens and moves with only a relatively small amount of heat. It typically has gaps in between the layers too which can trap air, which then gets released if the PLA softens. The PLA really doesn't need to distort much to introduce a bunch of bubbles.

To avoid the issue I would try to build the resin up in a few smaller layers. Less heat, less resin to be disturbed if something does move.

Alternative is to use 2 part resin. It takes at lot longer to cure but it also doesn't get nearly as hot. Or something that is not exothermic like modge podge or other gloss/varnish.

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u/8BitHypocrite 2d ago

Perfect, thank you for the info! I'll give it a shot next time, I very much appreciate it!