I assume you meant Aura, using Affinity colors? I used Aura in my daughters room, VERY nice paint but no way would I expect it to work well brushing, much less spraying (it dries waaaaay too quickly). Kudos for being able to brush with it!! Im looking at durability more than anything. Scouring the net led to recommendations for certain types of paint (mostly oil based) and some specialty waterbornes (Muralo UltraCeramic, SW ProClassic, etc). Thats why I havent really thought of a typical wall paint.......I know my doors will get beat up, so I wanted the best I can do (durability wise), while avoiding oil base (I need to spray in cold weather, so I dont want to leave the house open all day to get rid of fumes) -Chris

Runs and sags are caused by an overloaded brush; painting into corners instead of out of corner; too much paint a the overlap; and a few other things. Pro Classic is much better in appearance than SP. I'd practice more and continue using it. Spread the paint 6-8" from each wet edge. I think that will help you avoid runs and sags. At raised panels, always "tip" the corner with a brush tip to draw out any pooled paint. Michael

Brush marks are usually caused by over brushing and applying the paint too thin. If too thin, it's drying before it can level. Be generous, but don't over do it. Paintguy will tell you, you wouldn't believe how much paint we apply over a surface. Michael

Original poster here--it was not happening with just a new can of paint--it was happening with the bottom of one can of paint and with a brand new can, too. I find that I can get good results with ProClassic only when using a ton of extender. It works pretty easily on thin trim pieces, but you have to be so careful with doors, and the only way is to take the doors completely off, lay them flat, use a ton of extender (till the paint is almost like water) and then use A LOT of paint so when you come back to feather through it is still wet enough to not streak and clump. Even still you can't get a perfect job. Well today I am painting the front of an exterior door, and they recommended I used All Surface Enamel. It is a revelation how much easier this stuff is to work with! It still dries pretty quickly, but you can actually pull your brush through more than twice before it ruins the paint job. I wish I would have started using this long ago, it would have literally saved hours and hours of work and turned out much better results. I have no earthly idea how anyone can possibly use ProClassic straight from the can successfully on any surface larger than a couple inches wide or long. Oh and I have been using a really good Corona Excalibur brush, so that's not the problem.