Anti-corrosive mono-component chlorinated rubber undercoat is a highly waterproofing product, developed for underwater surfaces. It is ideal as sealer on old antifouling of unknown nature before applying the new antifouling. It allows to obtain a high-thickness and creates a true “barrier effect” between the water and the painted surface. It can be applied on properly prepared steel and wood both internally or externally of the boat. It is also recommended as an undercoat on emerged surfaces in mono-component painting systems.