[Ashlandchris]

I always finish with a coat of clear lacquer from Halfords (i'm sure other car paint suppliers are available...)
Make sure all waterbased paint is fully dry as the solvent based sprays such as lacquer which are more resilient can have the effect of "crackling" the WB paint if not properly dry. I tend to have a hairdryer, warm the shell, spray the lacquer on then dry with hairdryer and it works perfectly