Use a sharpened wood paint stir stick and remove any of the loose edges . It's rubberized undercoating and inside the doors was intended as noise suppression rather than rust proofing , I respray the inner doors again with rubberized undercoating after clean up and vacuuming out the bottom , Some thin plastic folded and inserted into the bottom door drains prior to respraying helps keep them open just wait about 30 minutes after spraying the inner door and then pull them out from the bottom of the door ,clean up with mineral spirits . it give the door a more solid sound when closing .
