Matt, use a hardner,but more importantly ,use fresh air. The hardner will make for a reliable coating,ask Hotrodpaint and Spraytech and they will agree, unless there is a 'newer' system out there that I don't know about. I speak from learning the hard way! Especially if you spray the entire vehicle at one time. Plastic is like putting yourself in a baggy with it! And, higher temps will make your lunges open up and absorb all of it without freshair and exhaust. I think the minimum is 100 cfm exhaust but check. Don't sacrifice your health just to get a paint job. I have read many of your posts and you are one that we would like to see continue,in a heathy way. Don't mock the manufacterures and gov. warnings. And I'm sure that the oldtimers of Clubhotrod will say the same,from expererience. Breathing hard is no fun,especially when your getting older.