I painted my bike with duplicolor rattle cans, waited about 3 weeks for the paint to thoroughly cure, and then painted a German company's urethane paint in a rattle can over the duplicolor.
Duplicolor is cheap and easy to use, has good UV and fading resistance, but doesn't stand up to chemicals (gas, oil, raod tar, etc) as well as urethane.
Paints like duplicolor cure boindg with the lower layer and through evaporation. Urethane cures through cross-linking. You can paint urethane clear over duplicolor rattle cans *after* the duplicolor has fully cured - but not vice-versa.
THis is how I did my bike, pics below:
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1) Perform any plastic repairs first.
2) Sand smooth to the eye and the touch. Hold the parts at several angles to catch the light so you can be sure they are really smooth.
3) Wipedown with MEK then Dawn dishwashing detergent works about as good as any commercial degreaser for prep. Don;t get the MEK on your hands, use good ventilation. Wash the parts in Dawn and clear water until the water evenly sheets on the entire surface of the parts. Do NOT use MEK once you've started painting. You can find MEK at the orange box store.
4) When you're done sanding, wash the parts with Dawn & water again. Then don't touch prepped parts with your bare hands - wear the cheapie plastic gloves you can get from almost any good-sized auto parts store..
5) Paint following the Duplicolor directions. Go very slowly and follow their directions in a dust-free well ventilated place.
6) Paint with duplicolor clear following the manufacturer's directions.
7) Wait 2-3 days, then wet-sand the clear and re-wash the parts, let them dry and put on a last coat of clear. Do not use any cleaner or wax just yet.
8) Wait 3-4 weeks for the paint to thoroughly cure, then degrease them with Dawn again and dry & paint several coats with this stuff. Be sure to allow adequate time between coats.
http://www.repaintsu..._2k_aerosol.cfm
Let this 2K urethane paint dry at least overnight before touching the parts. The smell is really nasty and will mess up your lungs if you don't use it in a ventilated dust-free place.
9) Wet-sand and polish if you like, but with the 2K urethane paint it's not really necessary.
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Sorry if this is a long rant, but basically don't sweat the paint choice. Use whoever has colors that you like and then go from there. Unless you urethane top-coat it, other paints won;t hold up to chemicals like urethane does.