I am using a high build urethane primer surfacer and I am having all kinds of problems spraying it. For some reason when I try to spray it comes out like rubberized undercoating. It dries with a sand like texture. 😡 The first time I thought that maybe my gun was contaminated, but when I sprayed it with a different gun I had the same results. This is a 2 part primer meaning I have to mix it in a 4:1 ratio with a catalyst. The primer itself is pretty thick, but once I mix in the catalyst it thins out decent. I wouldn’t think that I would need to thin it out further, right? Is this normal with high build primers? Is this primer junk? This is my first attempt at some body work and it seems I am already off to a rocky start. I would appreciate any advice.