The two main purposes of white coatings are to protect roof membranes, resulting in longer roof life cycles, and to reflect solar radiation, resulting in lower energy costs. A closer look at their formulations and components can go a long way in helping maintenance and engineering managers successfully specify and apply coatings and ensure maximum performance for commercial and institutional facilities.
In general, a white coating consists of a binder blended with pigments and other additives. Maintenance managers have literally hundreds of different white coating products formulated and manufactured by a range of companies. Most can be conveniently classified according to the binder they use.
Binders usually are made of an organic or silicone compound. Most binders are elastic polymers with elongation and tensile characteristics, or elastomers, which can return to their original shape after being stretched or deformed.
In white coatings, the elastomer binder is the viscous, pliant material that bonds pigments and makes them adhere to the surface. Common elastomers used as binders in white coatings include acrylic, silicone, rubber, vinyl and urethane.
Titanium dioxide and zinc oxide are common pigments that give coatings their bright white color, but manufacturers combine other pigments to yield a variety of pastel colors.
Most white coatings used today are water-based — often referred to as latex coatings — and are available in a variety of polymer types. Water in latex coatings serves as a liquid carrier, allowing applicators to spread the pigment and binder onto the surface as a thin coating.
For some white coatings, organic solvents carry the liquid, while others, called reactive coatings, might flow well enough to eliminate the need for a liquid carrier. Reactive coatings generally are prepared with multiple-part resins blended on site before curing.
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