Marine coatings are waterproof, protective layers that are applied to surfaces exposed to or immersed in fresh, brackish, and/or salt water. They are used with boats, ships, ferries and other watercraft, as well as with marine structures such as offshore oil rigs. Marine coatings include base coats, top coats and clear coats; paints, primers, varnishes, and stains; and inks, marking materials, and sealers or surface sealants. Like other types of protective coatings, marine coatings differ in terms of performance, properties and chemistries. Marine paints include epoxy fairing compounds, epoxy primers and sealers, and wood finishing systems. Anti-fouling coatings are also available.
Marine coatings can be categorized according to technology and are usually designed for specific substrate materials. Technologies include film drying and air setting, laser fusing and laser marking, multi-component systems, reactive or moisture curing, and ultraviolet (UV) radiation. Thermoplastic marine coatings melt repeatedly when heated and solidify when cooled. Thermoset marine coatings undergo a chemical reaction during the cure cycle when heated. Depending on the technology, marine coatings may be used with substrates made of aluminum, steel, or other metals; fibers or fabrics; asphalt, bitumen, or coal tar; plastics, rubber, or elastomers; and concrete or masonry.
Marine coatings differ in terms of performance parameters and processing specifications. Performance parameters cover conductivity, resistivity, dielectric strength, index of refraction, transmission, and operating or use temperature. Specialty marine coatings for saltwater or freshwater applications may carry additional specifications. With regard to processing, marine coatings are specified according to coverage, dry thickness and wet thickness, cure time and cure temperature, viscosity, volatile organic chemical (VOC) content, specific gravity, and particle size. Pot-life time, an additional parameter for marine coatings, is the time between the mixing stage and the gel stage at which a coating remains usable in the pot at 77o F.
Product form, method of application, color, finish and additional features are important to consider when selecting marine coatings. Some are provided as aerosols, crayons, films, liquids, markers, pastes, or powders. Other products are available as inks, solids, and transfer tapes. In terms of application method, marine coatings may require electrostatic, electrocoating, or powder coating techniques. Rollers, screens, and spin or spray coating equipment are also used. Although color choices vary, there are four basic finishes for marine coatings: flat, satin, semi-gloss, and high-gloss. In terms of features, anti-fog and anti-reflective marine coatings are available.