To survive cold winter temperatures, coatings need strong grain crack resistance and adhesion

Architectural exterior coatings work hard all year round. They have to withstand a variety of seasonal issues over the course of a year, from winter chills to summer rays to steady rainfall in autumn and spring.

Throughout all these external factors, coatings need to hold their color, structure and flexibility from the first application. As the professional painters’ market becomes more discerning in its durability standards for architectural exterior coatings, formulators aim to create products that hold up in changing weather conditions.

Winter is a particularly tough contender, bringing temperature swings that strain coatings and the substrates underneath.

It’s critical to achieve a balance between tensile strength and flexibility.

Camilo Quiñones

Market Segment Manager of Architectural Coatings at BASF

One of the key characteristics for a winter-proof coating is grain crack resistance, which measures the coating’s ability to withstand substrate movement without cracking.

Winter brings more pronounced temperature drops at night, which causes the substrate to contract under the coating. When the sun comes up again, rising temperatures cause expansion. Whether the substrate is wood, metal, vinyl, masonry or fiber cement, the coating needs to keep up with its movements to avoid cracking.

“Grain crack resistance is achieved when the latex exhibits a fine balance between film hardness and elasticity. Coatings should be flexible enough to withstand the movement and strong enough to maintain film integrity,” says Camilo Quiñones, Market Segment Manager of Architectural Coatings at BASF. “As the coating moves back and forth through the temperature cycles, it accommodates the resulting stresses without cracking.”

A weaker coating will eventually crack throughout the course of these cycles. When moisture gets in through cracks in the paint, it causes splitting, blistering and flaking.

“It’s critical to achieve a balance between tensile strength and flexibility — a balance that stays constant throughout the temperature changes,” Quiñones explains. “BASF has developed coatings that are very good at going through those cycles and withstanding those extreme changes.”

Products like BASF's Acronal EDGE 4247 have superior grain crack resistance, allowing them to withstand the most challenging temperature and humidity fluctuations. In the premium exterior architectural coatings market, Acronal EDGE 4247 offers formulators superior resistance to cracks and outstanding adhesion to multiple substrates.

Another key winter issue for contractors involves the ability to apply paint as outdoor temperatures get colder. To achieve good film formation at low temperatures, formulators usually use softer latexes, coalescing agents or both. However, either approach can bring undesired consequences.

“Soft latexes can lead to reduced dirt pick-up resistance, while some coalescing agents can substantially increase the VOC of the coating,” Quiñones says. “It’s critical to use a latex that can achieve good film formation at low temperatures without negatively impacting other properties, while simultaneously providing a broad formulation latitude so that formulators can effectively use other tools in their toolkit.”

Acronal EDGE 4247, an acrylic latex resin, is engineered to handle low temperature application without compromising on other important performance attributes demanded by contractors.

With the average coating’s winter woes covered, professional painters will look forward to spring and all the unique seasonal challenges it brings. As springtime brings more rainfall and shorter windows to apply new coats of paint, coatings need a new set of characteristics to make their work long-lasting and efficient.

Stay tuned for Part Two of our “A year in the life” series, where we’ll talk about the architectural exterior coating properties contractors need to prepare for the soggy days of spring and fall.

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