Urethane sealer with orange peel - need advice what am I doing wrong?

Weak440 said
I am working on sealing my '74 Duster with Nason brand Urethane sealer.

I am spraying it with a devilbiss finish line hvlp gun and am using roughly 9psi inlet pressure.

I have sealed the entire car and have been batteling orange peel. I started to sand it down with 600 and found a few spots on the fenders and doors that I want to touch up. I wanted to ask if anyone else has this sort of problem, if it is common, or is it something I am doing wrong?

It is kind of hard to get a good picture of it, the two attached pics are of my roof.

I'm pretty sure you need to turn UP the inlet air pressure (to get the 9-10 psi at the cap). most spec's call for air pressure AT the CAP but forget to tell (me)newbies you have to set the inlet at a higher pressure to GET the 9-10 at the cap. What tip are you using for the sealer, I use the 1.4 with my nason White sealer # 422-51 and 38 inlet air pressure to get 10 psi at the cap of the gun.
I'd look up the exact model of your gun and check the spec's to get the correct air pressure. a lot of pro's and tell at a glance but that ain't me.
hope this helps a little

here's a chart I found looking for the finishline type guns
http://www.devilbiss.com/LinkClick.aspx?fileticket=qjviHbZp_bs=&tabid=1023

I usually set my line pressure full open at the wall and use a regulator on the gun to (depending on the gun) mine is 30-35 psi with a 1.4 tip on the cheapie harbor freight I use to shoot epoxy on the car . and I think my devilbiss plus gun uses a little bit higher(I think it was 35-40) to hit the 9-10 on the cap. . 600 grit is to fine to do a leveling on sealer you need to back down on grit I'd start with 320 minimum but if the peel is really bad I'd jump down to 220 to block it and then go up (100 grit rule a lot of people say on the autobody forums) ie 220 then 320-400 (usually solid colors)then 500-600 after 600-800 (metalic finish work) you go 1000 1500 2000 for final color sanding ect