Good advice in previous posts:

1. Try a good bristle brush instead of foam.

2. Thin varnish sags less than thick - so if the can has been opened previously, it will likely require some thinning 10-15 percent max.

3. Warm the varnish in a bucket of hot water (only as much as you need for the coat you are working on) - warm varnish goes on thin, then cools and will not run - the viscosity increases with lower temperature.

A good brush job is hard to tell from a spray job.