Interesting article I found. How true is the article's claim that I've quoted?; "it's worth noting that two-part products are weatherproof and nonporous. You can leave your car in a 2K primer and not worry about the sheetmetal rusting from the inside out." http://www.carcraft.com/techarticles/ccrp_0709_automotive_paint/single_stage.html
Didn't read the entire thread, but in case this wasn't mentioned....do your bodywork, use a good primer system, then just throw on a couple coats of any old paint you have lying around, then put on a coat or 2 of your favorite color primer. We used to do that back about 20 years ago or more for better protection while the car was still being worked on, but not ready for paint. The primer was easier to spot in after doing more bodywork. Primer is NOT good protection!
You have to treat the bare metal first guys with metal prep, and then spray the PPG DP90 over it. Sure DP does not have the UV protection in it nor does any other paint companys epoxy that you want to spray on and leave as a black primer,red primer,gray primer so all that stuff you here and people tell you are not true. Also one guy stated the old DP was the best yes he was right i wish we still had that product but things change and they had to make it using the zinc and by the way DP has never been easy to sand it will gum the paper up due to the zinc in it. What you can do is spray the car with the DP if you like and put the PPG flat clear over it and then it will hold up for you guys DCU-2060 is the number it has the UV protection in it you need.So with that said good luck using the DP 90 or waht ever color you decide for your ride. Remember you got to have something with UV protect in it to last.
Not sure about the Epoxy you guys have over in the states but while its not UV friendly and will fade it does protect, I know of a 49 Ford that was epoxied 12 years ago and has sat outside a workshop in the UK under a tarp untouched and is still as good as the day it was done.