Oct 142009

This is how I deal with air bubbles found in resin kits. Sometimes these bubbles are just under the surface and while sanding to clean up mold lines or various surface defects, they are uncovered. Other times they are quite obvious and are easily spotted. And more often than not, they are not easily seen and are very small, and up until you spray that first layer of primer, do they suddenly show up all over the place. So this little tutorial will demonstrate a few methods I use to deal with this pesky little issue.

The first step is to cut open the bubble. The bubble that we normally see is usually just the top of the problem. Think of it as the tip of an ice burg, where the major problem is MUCH bigger and completely below the visible surface. For any sort of filler to work, the filler needs to attach itself to as much surface area as possible, and if we were to fill the bubble’s top or just the tip, the filler has nothing to attach to and the sanding process will just work to remove the putty. So the first step is to cut the bubble open exposing the entire bubble and giving that much more surface area for the filler: liquid putty, epoxy putty, ca glue, etc:

For this example I used tamiya light curing putty to fill in the cut open area.

Turn on a desk lamp over the putty area for 3-5 minutes to cure the putty.

Then sand away the excess. Priming will show if the problem has been fixed or not.

The above was an easy fix as it was just one hole and was easily seen prior to priming. I ran into this problem right after I primed the part…

Again, the first step is to Cut open all the holes, or as many as I could…

This time, I used Tamiya epoxy putty quick type(cure time 24 hours) as the filler.

Then sanded the part after allowing the putty to cure.

For my time, I like using the tamiya light curing putty as it sands just like resin and with the cure time, if I didn’t get the hole completely filled, I can always add in some more putty and resand. The whole process takes nothing more than 10 minutes. This is in comparison to using slower curing putties such as epoxy and liquid putties. Yes, I know there are quick set putties (5 minute, etc), however the problem with those is that you have less than 5 minutes from mix time to set. With the light curing putty, I have as much time I need to fiddle with it, then when I want it cured, I turn on the desk lamp.

As for CA glue, I just find that CA glue is too hard to sand when it cures. I end up sanding more of the surrounding resin than the ca glue when fixing holes because of the different hardness of the cured CA glue and the resin.

Here are some additional examples of fixing surface defects with light curing putty.

After repriming, there were still some issues so additional attention was needed.

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