Mine are pretty cracked but don't want to buy new ones if this idea will work. I am going to black them out anyway, but I was so seeing if i can epoxy and sand them, if that would work to seal the cracks some?

 

I don't see why it wouldn't seal them to the point of locking out moisture. If you are going to black them out, that would be an extra layer against moisture.

I think the real point is, if it doesn't work, you'll have to buy another set, or you could just buy another set now. EG, try it unless time is the main issue.