If you lightly sand enamel paint then apply acrilic it will bubble the enamel . Uh, this is just something i heard from somebody who knows somebody who did this on a bike project once....
Aparently the next night he removed the masking tape and the enamel pulled away from the primer. Now it will be necessary to strip or sand it all down again and start over. yay....Bummer for me..i mean that other guy