text: A coating or paint is usually a fluid applied covering applied to a surface in contact with a corrosive situation such as the atmosphere. The surface is usually called the substrate. In corrosion prevention applications the purpose of applying the coating is mainly functional rather than decorative. Paints and lacquers are coatings that have dual uses of protecting the substrate and being decorative, but paint on large industrial pipes as well as preventing corrosion is also used for identification e.g. red for fire-fighting control etc. Functional coatings may be applied to change the surface properties of the substrate, such as adhesion, wettability, corrosion resistance, or wear resistance. In the automotive industry, coatings are used to control corrosion but also for aesthetic reasons. Coatings are also extensively used in marine environments to control corrosion in an oceanic environment. Corrosion will eventually breakthrough a coating and so have a design life before maintenance.