Roof coatings are waterproof, protective layers used in environments where wind, rain, snow and other precipitation can damage a building’s roof. Typical applications include warehouses, chemical plants, manufacturing facilities, and commercial buildings. There are many different types of roof coatings. Choices include coatings, paints, and primers as well as inks, stains, marking materials, and sealers or surface sealants. Coatings vary in terms of properties and chemistries. Paints include products made of enamel and lacquer. Marking materials are used for rooftop identification while sealers are designed to seal gaps in a roof’s surface.
Roof coatings carry specifications for technology and may be designed for specific substrate materials. Common technologies include film drying and air setting, laser fusing and laser marking, multi-component systems, reactive or moisture curing, and ultraviolet (UV) radiation. Thermoplastic roof coatings melt repeatedly when heated and solidify when cooled. Thermoset roof coatings undergo a chemical reaction during the cure cycle when heated. Depending on the technology, coatings can 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.
Processing Parameters and Performance
Roof coatings differ in terms of processing parameters and performance. Processing parameters include coverage, wet thickness and dry thickness, cure temperature and cure time, volatile organic chemical (VOC) content, viscosity, specific gravity, humidity and particle size. Pot-life time, an additional parameter for roof coatings, is the time between the mixing stage and the gel stage at which a coating remains usable in the pot at 77o F. Performance specifications include conductivity, resistivity, dielectric strength, index of refraction, transmission, and operating or use temperature. Specialty roof coatings for specific applications and industries may carry additional specifications.
Selecting Roof Coatings
Form, application method, color, finish and features are important to consider when selecting roof coatings. Some products are provided as aerosols, crayons, films, liquids, markers, pastes, or powders. Others are available as inks, solids, and transfer tapes. In terms of application method, roof 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 roof coatings: flat, satin, semi-gloss, and high-gloss. In terms of features, anti-slip products are available.