Rick~
Interesting coincidence. I just picked up 2 quarts of Satin Spar Varnish from my local ace hardware. I had ordered it just to have on hand. As I was leaving, the Ass't Mgr advised me that most of their products with traditional oils - e.g., spar varnish, Minwax oil stains, etc., will be unavailable to them as of January 1. (Probably NYS rule to reduce VOCs)
So, on the drive home, I pondered the option of epoxy as a cork sealer. The $71 I pay US Composites for their gallon-and-a-half resin + hardener kit (635 Thin Resin) is less than I pay for Spar Varnish. I buy the quarts simply because I open and close the cans so often that gallons are impractical.
One more Big Decision to make going forward.....
All the best,
SJS