To prime or not to prime?
QShould I apply the black bitumen paint directly to the hull, or apply a primer first such as red oxide? TONY REPLIES... It has been stated that red oxide reduces the blacking’s adhesion but I do not know if it is true. International
A( Primocon) underwater primer should be okay to use under blacking, but I am sure at least half of all boats have no primer. The manufacturer of the blacking should be able to advise further.
Make sure you really scrub the first coat into all the rust pits; a roller is normally okay for further coats. Some people either use a thinner product or thin the blacking for the first coat.