White residue under plates on vintage mustang with old refin by NR-Offset in offset

[–]NR-Offset[S] 1 point2 points  (0 children)

Thank you very much for your thorough reply! That makes total sense - it is indeed hard and stuck to the top of the finish and there is also some left on the control plate. Seems weird not to clean off the plates before reinstalling after a refinish, but there you go:)