How roofing manufacturers classify roof coatings

Roof coating systems are available for a variety of roofing systems. Manufacturers like Conklin are introducing new formulas to keep up with changing needs and roofing materials with water-based urethanes, bio-based materials, 100% solids silicones, and low volatile-organic-compound asphalt cutbacks currently in the pipeline. Also on the horizon are self-cross-linking water-based coatings, faster-setting water-based coatings, and a basecoat primers suitable for literally every roofing membrane on the market.

Manufacturers classify roof coatings according to the specific binder and carrier type, which also determine application methods and compatibility with existing roof surfaces.

A coating’s binder (or resin) is the basic matrix material - the part that actually adheres to an existing roof surface. Manufacturers use different binder chemistries to meet price and performance criteria, as well as to match specific roof substrates. The binder type dictates most of a coating’s primary physical properties including elongation, tensile strength, adhesion to a substrate material, permeance, water swelling, and low-temperature flexibility. They typically range from asphalts to a variety of elastomers (acrylics, urethanes, silicones, thermoset rubbers and various block polymers), as well as blends of these materials.

A coating’s carrier is the liquid that combines with the binder to reduce viscosity to a workable level. The carrier generally evaporates during curing. It also generally dictates a coating’s installation process and cure time. Manufacturers now more often use water as a carrier, in which case the binder is suspended in water as an emulsion though traditionally coating binders used a solvent as the carrier. Solvent-based coatings cure in a broader range of weather conditions and might be the best (or only) choice in freezing or wet conditions.

A coating’s cure rate varies greatly because it reacts to ambient humidity, temperature and sunlight. This reaction is especially true of water-based coatings. Coating installers must allow coatings to cure sufficiently to ensure they are waterproof.

Manufacturers can add pigments and fibers to binders to control physical properties and increase reflectivity. Because reflectivity and emittance are defining properties of cool roofs, organizations such as the Energy Star program and the Cool Roof Rating Council in California monitor and measure these coatings.

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An Overview of White Roof Coatings: Part 1

There are two main purposes of white roof coatings like those from Conklin. The first is to protect roof membranes and provide longer roof life cycles. The second is to reflect solar radiation and lower energy costs. Generally speaking, a white roof coating consists of a binder blended with pigments and other additives. Most roof coatings can be conveniently classified according to the binder they use.

Binders, Pigments & Liquid Carriers

Binders are usually made of an organic or silicone compound. Most binders are elastic polymers with elongation and tensile characteristics (also known as elastomers) which have the ability to return to their original shape after being stretched or deformed. In white roof coatings, the elastomer binder is the viscous, pliant material that bonds the 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 the common pigments that impart a bright white color to the coatings, although other pigments can be combined with these to yield a variety of pastel colors.

The majority of white roof coatings are water-based. These products (often referred to as latex coatings) are available in a variety of polymer types. The water in latex coatings serves as a liquid carrier, allowing the pigment and binder to be spread onto the surface as a thin coating. For some white roof coatings, organic solvents are used as the liquid carrier, while others (often referred to as reactive coatings) may have sufficient flowability to eliminate the need for a liquid carrier. Reactive coatings are generally prepared with multiple-part resins often blended on site, before curing.

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ROOFING CONTRACTORS NEEDED IN MULTIPLE STATES!

Patton Services | (309) 303-3128 | rpatton55@comcast.net | http://www.whiteroofingsystems.com