Auto body repair & detailing: Paint question., grit sandpaper, spray cap

Question
I am refinishing a 2 foot by six foot panel on a Haulmark trailer, thin sheet metal. Haulmark hooked me up with the paint company they use to pain all of their sheet metal. They sent me paint and a clear coat, rattle can style. I have applied both. The clear that they sent doesn't come out in a nice even spray pattern. When it lands on the panel it seems to be blotchy. Can I sand this with 1500 grit sandpaper to smooth it out and then polish it? If so what do I need to purchase to polish it? I'm seeing now that I probably should have taken it to a professional, but want to try and save it before I spend the money for a new panel through Haulmark. Thanks for you time.  

Answer
Hello Brad! Rattle cans seldom do a nice job laying down anything, The panel you are doing is just a little too big to rattle can. You  can try to polish it out with 1500 and 3M medium duty rubbing compound, but be prepared to scrub your arms off. It really takes a buffer to polish out even 2000 grit sand scratches, and I mean a professional buffer. The nicer you get the clear on, the better off you will be. Try putting a different spray cap on the paint can, maybe the one on it is fouled. be sure to shake the bejesus out of the can, also, at least 2 minutes. If they still make it, rustoleum clear was a great spraying rattle can clear, but you have to tarp everything off, or it will leave overspray everywhere. Bill