Air bubbles

[mmdm4]

I have some resin parts I am going to use on a build and I was wondering how to repair small air bubbles? They aren't very big so I was wondering if there is an easy way to fill and sand, or what is the recommended way to repair this small flaw? Thanks

[Ace-Garageguy]

In ANY "composite" material, fiberglass or "resin" or "bondo", air bubbles often tend to be undercut, meaning they're bigger under the surface than the hole that shows on top of it. Because the diameter of the bubble is larger under the surface, simply screeding in your filler of choice won't fill the entire void, leaving the likelihood for show-through when the part is primered and painted. This happens frequently on real full-scale parts and bodywork, as well as on resin models.

If this is the case, it's necessary to take the tip of an X-acto and open-up the bubble on the surface, larger than its diameter under the surface. Try to make an even-tapered radius so that your filler will be able to completely fill the void without trapping any air in it.

I'll leave suggestions for what specific material to use for correcting "resin" voids to the guys who do a lot of work with the stuff. The under-surface bubble problem is pretty much universal, however.

All these holes need to be opened-up and radiused BEFORE they're filled, for top-notch results.

Edited July 31, 2014 by Ace-Garageguy

[Lunajammer]

If they're actually pinhole bubbles and not BB size bubbles, a spread of super glue works fine and sands well. Bigger than that will require 2-part fill as mentioned above.