[quote user="Treehugger Dave"]
See these kind of problems here often over the years. Been here since '07.
I too have painted 1 to 1 cars - since the mid 70's, built model since 1950 as well as airbrush. In your case, air pressure is too low, paint isn't thinned enough, and you aren't keeping the metallic mixed nearly enough. Metallics settle almost instantly, so I swirl the paint to mix after 2 passes.
Oh yeah, guy's hate this part and call me a liar and other things, but I shoot with the largesT spray nozzle I could find for my airbrush, and I never shoot below 60 PSI - Yeah no kidding. Works great for urethane filler primers too.
My walls are plastered with awards for my cars including multiple best paint. You can't argue with success - Well, I guess ya could .
I'm glad someone else has weighed in Thanks Dave!
I agree in most part what Dave has offered, If your reduction rate is 1 part paint and 6 parts reducer you are way over reduced on your paint, typically reduction rates are 1 part paint to 1 to 11/2 parts reducer as a rule of thumb, However I use the manufactures recommended rate of reduction and adjust from there.
Dave is absolutely correct in that metallics settle fast. It is imperitive to keep them in suspension as much as possible, On my top feed airbrushes I always give the AB a shake or two during the painting process, with my bottom feeds I add a couple BBs to the jar and give them a swirl. My full size guns employ a agitation device.
I don't think Dave is lying when he says he uses 60 psi, it's a common practice when color matching in a collision shop. Have I used it painting models? NO but that doesn't mean it doesn't work.... His results speak for themself.... Excellent work!
I'm sure Dave would agree with me that at that high of pressure you do use more material and create more overspray but again it does works!
I also subscribe to his large nozzle size.... All of my guns have the largest nozzle size I can purchase as you can always throttle the fluid rate down. It's kind of like can you ever have too much Horsepower.....
Based on the information you provided the two big red flags for me were your rate of reduction and nozzle size.
After you address those issues you may be on your way!
Laying down great paint doesn't have to be that difficult and quite frankly isn't. It just takes a bit of time, practice and good overall practices.
Always paint with good lighting, try to maintain a 50% overlap on your passes. Watch as your paint hits the surface and then look at the results, it will tell you the story! faster, slower, closer, farther. It can be a exhausting exercise, however it WILL pay off in the long run.
I hope this helps.... always here to lend a hand!