Dirt Under BASECOAT: Description
WARNING: This page is about a different car, the 2019 Jaguar XE. However, it is still accessible from the selected car via links, so may be relevant.
Dirt under basecoat is often mistaken as blisters: the effect is similar, appearing as hard lumps or bumps in the finish. The exception will not deteriorate neither will it result in film failure. The contamination is of no defined size. The exception is hard and will not give way when probed with a blunt object or fingernail, unlike soft blisters.