Just a little off topic, but it concerns schooner varnish. I am getting persistent bubbles. I have been very careful about stirring, and I am on the 6th coat, and still getting them, the first couple of thinned coats I did not get them. The last couple coats I have been using non thinned varnish. Any suggestions???
I had the same problem with Schooner varnish. It was most obvious trying to get that last perfect coat on. If I used it full strength it was too thick and I got brush strokes. It also seemed to start curing almost immediately and get even thicker as I applied it, even on relatively small areas.
However when I thinned it I would get bubbles, every time. I was quite careful with stirring and brushing. To be sure I would carefully inspect my cup after stirring to verify no bubbles at all in the varnish. Also experimented with various brushes and various strokes. Always I would get micro bubbles.
Starting inspecting the work very closely and I swear it looks like the bubbles were appearing in the varnish after I applied it, just like bubbles appearing in a soda. It's like the varnish was generating the bubbles. My theory is the thinner was causing some kind of reaction that generated the bubbles and I tried every kind of thinner I could think of: Schooner brushing thinner, mineral spirits, generic thinner and a couple more that I can't recall. All had the same result.
I even called tech support to ask but they couldn't come up with a solution.
One thing that I tried that helped a little. I warmed the varnish before applying (without thinner) to reduce the viscosity and slow the curing.
Finally gave up and used a urethane for the final, smooth coat. Will see how that works over time.
Only other idea I have is to try another brand of varnish.