In Part One, we discussed exterior coating issues specific to winter. Read it here.
Part Two explores the elements exterior coatings need to resist in spring. Read it here.
For many of us, longer days and summer rays bring plenty of tanning opportunities — for architectural exterior coatings, on the other hand, summer brings challenging conditions that can lead to changes in color and other aesthetic disparities.
Building owners want consistent, uniform color all year long. How do coating formulators and professional painters deliver that integrity in the face of summer sun and heat? Let’s take a look.
Keeping colors bright and consistent
Summer involves long days with plenty of sun. Paints and coatings undergo prolonged exposure to UV rays and need to be formulated to withstand the elements.
“When it comes to withstanding sun and UV rays, color fade resistance is key,” says Camilo Quiñones, Market Segment Manager of Architectural Coatings at BASF.
As time passes, pigments lose color and fade in the sun, though some are affected more than others.
“While there is a broad spectrum of resistance to fade across pigments currently in use, commonly used organic yellow, blue and red pigments tend to have a higher propensity to fade,” Quiñones explains. “UV degradation can lead to sharp changes in color in paints with high colorant loading and when different pigments are mixed to achieve a specific color. For example, green could turn into blue as yellow fades.”
Colorants are a key driver of performance.
Market Segment Manager of Architectural Coatings
Not only do coatings lose color in the sun, but they also lose their uniform appearance as different parts of a building contend with more UV exposure than others.
“In North America, south-facing walls spend more time in the sun,” Quiñones says. “Any areas with an overhang — such as a balcony — create shade on certain surfaces, which will prevent these areas from fading.”
The result is an obvious disparity in colors where sunlight hits the building at different angles in varying degrees.
To stay vibrant, consistent and resistant to UV light, coatings must be formulated with polymers that prevent color fade. BASF’s Acronal® EDGE 4247 and Acronal® PLUS 4240 latexes are designed with those factors in mind.
“Colorants are a key driver of performance,” Quiñones says. “We have colorants that combine high-end pigments to provide vibrant colors and excellent resistance to fade.”
Quiñones also recommends combining these products with UV stabilizers, such as Tinuvin® and Irganox®, to prevent color fade and chalking and create a reliable formulation.
Glossy, not chalky
Thanks to the summer sun and exposure to the elements, coatings can also lose gloss overtime. This is especially noticeable in high-gloss coatings, such as the ones used in doors, window frames and trim details. That’s where gloss retention comes in handy.
Another common problem related to UV exposure is chalking. It appears as a white, powdery substance that hazes the color of the paint.
“Chalking occurs when the polymeric chains in the paint degrade and break apart when exposed to UV rays,” Quiñones explains. “The residue left from the polymer degradation becomes loose, forming a white dust on the paint film's surface.”
“The chemistry of our Acronal EDGE 4247 and Acronal PLUS 4240 polymers make them very good at withstanding chalking,” he adds. Formulators can leverage BASF’s robust portfolio for exterior applications to develop coatings that display excellent color retention, gloss retention and resistance to chalking.
Formulating with seasons in mind
To ensure their products are always raising the bar for exterior architectural coatings, Quiñones mentions that BASF maintains an exterior weathering program in Charlotte, NC, Wyandotte, MI and Orange County, CA.
“We have test fences where we expose samples with different paints, substrates and formulations for long periods of time,” he says. “We leave them outside in a south-facing direction for many years. We grade them every six months to see if the color has changed, if the gloss has degraded, or if there has been chalking, cracking, dirt pick-up or surfactant leaching.”
He stresses that testing for performance is important for many reasons — not only so formulators can provide high-quality products, but also “to ensure that professional painters can trust us with their reputation and homeowners can trust us with the appearance of their houses.”
“A pro painter must be skilled at choosing paint,” he notes. “A typical homeowner pays thousands of dollars for an external paint job — one that comes with warranties and involves extensive, demanding preparation. So, it’s critical that pros use high-performance products that don’t fade or crack.”
Summer is an important season for contractors and painters. With the right exterior architectural coatings, pros can avoid repeat jobs and keep their businesses in good standing — all while providing building owners with vibrant, consistent-looking paint jobs that will last for many summers to come.