bubbles in clear casts?
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bubbles in clear casts?

Posted in Custom Workstation

Hey guys, new to the forum and was wondering if any of the DIY casters can give me some tips.

been teaching myself how to cast stuff over the past few months so I can make myself some clear resin energy blast accessories to go with my Marvel Universe figures and I'd been getting tiny bubbles along the seam line. mainly been doing 2 part silicone molds, filling both halves, then letting em sit for a bit and slapping the 2 parts together carefully. mainly doing that so I can fill every bit of the mold with resin and pick out the bubbles with a toothpick.

wondering if there's certain way to go about making my molds so they're optimized for this or a better way of going about the process. outside of vacuum chambers and pressure pots since I don't have access to those or the money to buy em just yet. thanks in advance!

Posted by NoodleChow
on Sunday, February 19, 2012
User Comments
RedRebelCustoms -
Thursday, February 23, 2012
A pounding board works well in lieu of a vacuum chamber. I have a lot of links posted in the casting questions sticky. They have some great info. Make sure too mix it well and pour slowly. I've used Easy Cast from Cast'n Craft with great success as the product has a feature that eliminates bubbles but any clear casting resin is basically bondo fiberglass resin. With the right mixture you can use bondo. It is cheaper so you can experiment with it to get the right mixture. You can also use your mixing stick to lightly push the sides of the mold to decrease bubbles in detail areas like noses, ears, flames, etc. Hope any of that helps.
Ole Jade Jaw -
Wednesday, February 22, 2012
Alumalite and the Smooth-on products tend to bubble a lot less than the cheaper craft store resins. I know I started with the Castin craft stuff from Michael's and if was a nightmare. I don't cast with a pot myself, and I may throw out 1 in 10 casts due to imperfections. You also may be squeezing air out through the seam when you close the mold, forcing air to be trapped and bubble. That's just a guess though.
NoodleChow -
Tuesday, February 21, 2012
hmmmm.... you're right. did more research on pressure pots and I think I'm gonna have to save up for one along with an air compressor. think that'll be better than pulls that took almost a day to cure only to find bubbles anyway. so far I think I have a 20% success rate with clear resin by itself. the pressure pot would be super sweet in this case. thanks for the reply!
Patraw -
Tuesday, February 21, 2012
I think a vacuum pot/chamber is the only sure way to prevent bubbles. You could try tapping/whacking the mold on a hard surface to try to shake them out (although if you're only getting them along the seam, I would think that the actual process of joining your two mold halves is where the problem lies.) Rather than doing the halves separately, you could try pouring the resin into the fully assembled mold, but you might get air bubbles with that method too if the air can't escape fast enough (multiple paths/sprues for the resin to flow through, and the air out, can help alleviate that, but it's still no guarantee.)
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