I've been practicing my varnish techniques on my hatch covers while I wait a couple weeks for the epoxy on the yak to cure. But after my 3rd coat I'm still having trouble with bubbles in the varnish. I'm putting it on with a foam brush (seems like a good quality foam brush). When I put it on, stroke in one direction and flow it on, there are quite a few tiny air bubbles. After a min or so most are gone but a dozen or so remain in the 1sqft cover. There does not seem to be any bubbles in my cup of varnish. Also tried thinning with 10% thinner but had same result. Any ideas?

They sand off easily with 220 and 320 wet sanding. But I'm concerned the final coat will have bubbles.

Dwight