I've been using por15 for years and never seen anything like this. Did you shake the can? You can't do that because you get air bubles in the paint. You have to stir it really well but in a slower motion. I've had really good results and I love the stuff. I should mention that I don't use the prep stuff. I also have never sprayed it. It flows out like glass with a brush. I paint right over rust. Use a lot of paint as in a heavy coat and apply 2 or 3 coats. Recoat when coat is just tacky enough to leave your finger print.