Epoxy primer is recommended for superior adhesion and corrosion protection properties. For best results, prep bare aluminum surfaces with TotalBoat Aluminum Boat Etch Wash, then prime with TotalBoat Aluminum Boat Barrier Coat. For other underwater metals with no existing coatings, prime with TotalBoat TotalProtect Epoxy Barrier Coat and Primer before applying TotalBoat Outdrive AF Spray.