Bubbles in smoothcast


New Member
Guys this is my first post here........hello to everyone. My post is not related to props, costumes, or models but rather fishing lures.

My hobby is building fishing lures and I pour a good number of them from smoothcast. When I put an epoxy clearcoat on them to protect the paint I often get tiny pinholes where I assume air is escaping.

I should mention that I am pouring the smoothcast into both one part and two-part silicone molds. I am also using microballoons in the mix to lighten the resin.

Has anyone here found a way to prevent the pinholes?

Thank you!!


After you pour your resin just tap (vibrate) the mold a bit before the resin sets to get those airbubbles to flow to the surface (coating the mold with a thin coat of baby powder helps too), another little trick is to wet your gloved finger with the resin and rub the mold thoroughly before filling it up..... this will eliminate any chance of airholes forming on the surface of the mold. Also, make sure you wear at least a dust mask when using microballoons, it's EXTREMELY carcinogenic!! I can't believe you were able to find that stuff since every place I know doesn't carry it anymore due to the extreme health hazard.
When i first read the topic "Bubbles in smoothcast" I thought "oh, someone made a Michael Jacksons chimp sculpt and just made a mold of it." :p Silly mind i have.:behave
What is the cure time of the resin? You may want to use at least a 30 minute cure time. This will allow bubbles to float up within the 7 minutes gel time. The tapping and baby/talc powder is also a good suggestion. I sometimes put my molds on the dryer and run it to let the vibration force the bubbles up as well.

Thanks for the help,

Maybe I wasn't clear, it's not that I'm getting bubbles in the cast pieces, it's that air is escaping from the cast pieces after I paint and clearcoat them which then causes pin holes in the clearcoat.
So what I end up with is a clearcoat with tiny pin holes here and there......just a few of them, like maybe 3-5 on each piece.

My molds are designed so that all of the air can easily rise to the top and out of the mold so I'm suprised that this is happening.

I could try some kind of sealer over the cast pieces before painting but I would prefer to not have to do this additional step.

Any ideas?

Thank you.

I take it that the colour paint you are using matches the clear coat you are using?

Are you brush painting the lures then spraying the cear coat?

If you are spraying the lures with the clear coat at what distance from the lure do you hold the can, because if you spray too close with a rattle can you can get air bubbles in the paint/clear coat.
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