Guys, i need your help. How do you airbrush this stuff:

Whenever i try to spray it it ends up all grainy and not shiny at all... What pressure do you use and do you thin it or use it from the bottle?

Also, how do you spray Future/Klear/Pronto? I had even less luck spraying that stuff than vallejo...

Wanted to start gloss coating P-40 today and luckily i tried it on scrap piece first. I almost ruined the model...

Cheers!