: ...The recommendation is to
: apply it over epoxy without thinning, but I finally broke down and bought
: a can of the thinning solvent because it is too viscous to tip-out with a
: foam brush, and bristles leave brush marks.

For those who may want to try spraying varnish, here are a couple tips.

Application: Thin 40-50% with acetone. Spray on a thin coat, wait 10-15 minutes until it tacks up, then follow up with a thicker coat. Not too thick or it will run and drip, just as with a brush. Some experimentation on scraps or mockups is in order here.

Equipment: Airless rigs do not have sufficient adjustability for fine work like this. The only control the user has is swapping out different-sized tips. Air-atomized spray rigs work fine, and have delicate adjustability, but unless you have one already it wouldn't be worth the expense to buy one and the time to get good with it. Setup and cleanup are a chore, too. HVLP (High Volume Low Pressure) is the wave of the future, providing better paint transfer efficiency and less overspray. There are two basic types available.

Hybrid HVLP systems take ordinary ~100 psi air from a compressor and reduce it to 8-10 psi at the gun using pneumatic prestidigitation. True HVLP systems use HVLP fans instead of compressor air, running at 3-4 psi. The one shown below is the lowest-cost unit available presently, on sale at Rockler for ~$80. Santa dropped one off here last month and I refinished our kitchen cabinets with it, worked fine and quickly. Cleanup took 5 minutes. After the remodel is done I plan to spray a boat with it, and will report back.