On Tuesday, September 19, 2017 at 8:40:19 AM UTC-5, JBI wrote:
I have a small glass dome with a wooden base identical to the one shown
he

http://www.hobbylobby.com/Home-Decor...ase/p/80827902

I do entomology as a hobby and placed several butterflies in the dome
over the Summer and then sealed the base to the glass with silicone so
that small bugs could not enter and eat the specimens. I also hid some
moth flakes inside the dome to ward off these pests just in case they
broke through the seal. I didn't think I would have any issues
afterwards, but I am having one--- I can smell the moth balls outside
the dome, which means the wood is allowing the ball gases to escape.
This isn't good as it's a hazard to breathe moth ball gasses. For now,
I've moved the dome to an unoccupied area of the house until I find a
solution. Is it possible to coat the wooden base, up to the point where
it meets the silicone, with something to seal the wood and make it
airtight and, if so, what would it be? In a pinch, I was thinking of
melting wax and then "painting" it on the base, but not sure this would
work or even be effective.

Thanks in advance for any help.

Also consider, it may not be the wood that's the problem. Your silicone seal may have been compromised, allowing fumes to escape. If your dome unit was purchased, I would think the wood aspect has been sealed, hence giving credence to the silicone seal breakage.

Otherwise, seal the wood with pretty much any poly, lacquer or shellac. Lightly sand the wood before applying the finish. I would use shellac (Sealcoat, available at most any hardware/paint outlet).

Sonny