painting help

[Duncan]

I am using cans to paint my shells, i always clean the shells before i paint and i try to spray thin layers and i wait until the paint is well dry before giving another coat. But i always seem to suffer from the paint cracking and then peeling after a few races in small places. what am i doing wrong and should i be using some sort of tough backing paint as most of the pro shells i have seen have some sort of a grey backing paint.