Looks like some fisheyes around the grain which maybe something in or on the surface affecting it to lay flat....I have thinned the Helmsman with some mineral spirits, it just depends on the gun tip size...My Binks M1G gun will spray it thick easily...but you would have to experiment....You can add a additive like Smoothie to help eliminate fisheyes...
http://www.3m.com/3M/en_US/company-u...3082710&rt=rud
If you would like you can run up here with the wood and use my gun..you can knock it out...glad to help
Joe