At Carlisle, there was a restorers panel session and they all said always remove it down to bare metal. Plus they said to always wear a mask because the black coating is a lung health hazard!! I had not heard that before.
Jim


1970 Superbird 440-6bbl, auto
1969 Barracuda 340-4bbl, FB Formula S auto
1969 Barracuda 6.1 L Hemi, 5 speed, Convertible
2022 Can Am Spyder RTL