Painting old Ford in flat black ,Hot Rod Black OMNI AE premix. Gravity feed HVLP gun 1.4 tip @30 psi at gun, temp 68 F. When dry (2 coats)you can see the pattern overlaps and stops by a difference in sheen. Where it’s slightly thicker it dries satin, instead of flat. It shows more on the horizontal panels. I’ve never sprayed a paint with a flattening agent in it. I know it was very well mixed, but I don’t know what temp range reducer was used in this premix. Other panels previously painted at 58 degree temp were the same streaky look. Was advised warmer temp would fix it.I was happy with the color coverage otherwise, and on glossy paints my spraying technique seems OK. How do I fix this. Is there a post paint procedure used on these flat finishes or is it my spraying methods. Any advice would be super.