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Reducing VOCs with Water-Based Exterior Coatings

TUESDAY, DECEMBER 5, 2023

By Lon Bauer, Product Development Manager, APV Engineered Coatings


While concentrations of volatile organic compounds (VOCs) are consistently higher indoors, they also are a concern outdoors. Once in the atmosphere, they react with oxygen to produce ozone, a key component of smog that can lead to adverse environmental and health effects.

VOCs from coatings can be a nuisance to contractors, building occupants and passersby. They can also be drawn into a building through open windows and HVAC systems, compromising indoor air quality. 

Water-based coatings can be applied with minimal impact to crew safety and comfort. PHOTOs COURTESY OF APV ENGINEERED COATINGS

Why Coatings Contain VOCs

VOCs in solvent-borne coatings usually come from the solvents themselves. Solvents offer an efficient, low-cost means for dissolving and dispersing raw material components, and they evaporate rapidly, shortening dry times. Solvent-based formulations have an inherently low surface tension and will wet out on a multitude of substrates without the use of additives. They help a coating adhere well to substrates that have less than pristine surface cleanliness.

To reduce VOCs, water can replace sol­vents in coatings, but a small amount of co-solvent is often retained. VOCs in a water-based coating are usually found in the resin or binders, thickeners, additives such as defoamers and surfactants, and pigment. Each ounce of colorant added to tint paint may contain between 5 and 20 grams of VOCs. Darker-color coatings, which require more pigment, could add 300 or more grams of VOCs per gallon of paint.

In general, higher concentrations of VOCs are found in extreme-durability, solvent-borne polyurethane and acrylic topcoats and pre-treatment wash primers, where they run in the 5–6.5 pounds per gallon (600–700 grams per liter) range. Low-VOC water-based coatings typically contain less than 100 grams per liter. Five grams per liter is considered “very low” or “zero.”

VOC Regulations

While few regulations or standards exist for VOCs in outdoor environments, states such as California are taking a more aggressive approach. Its South Coast Air Quality Management District (SCAQMD) adopted Rule 1113, the strictest, most comprehensive restriction in the U.S. Many other states and manufacturers follow it as well.

Application methods that limit thinning of the product, such as a brush or roller, can reduce VOC emissions.

Blending Safety and Performance

Understanding the characteristics of polymer chemistry, rheology modifiers and co-solvents, APV chemists have formulated water-based coatings to optimize a continuous film formation without the need for solvents. With less than 50 grams per liter of VOCs, APV’s NeverFade Original Topcoat is one of the few high-performance coatings to meet SCAQMD Rule 1113 environmental regulations. It also meets 40 CFR Part 59, Subpart D, National Volatile Organic Compound Emission Standards for Architectural Coatings, which caps emissions at 380 grams per liter. The topcoat’s complementary primers also contain less than 50 grams per liter of VOCs.

Some users of high-performance architectural coating technologies may believe that water-based coatings do not provide the same ease of use, long-lasting durability, weatherability and color-retention as solvent-based coatings. Thanks to the introduction of Kynar Aquatec, a polyvinylidene fluoride (PVDF) water-based resin emulsion, this is no longer the case. Serving as the binder in APV’s water-based NeverFade coatings, this tough engineered thermoplastic has a two-decade record of performance in extreme conditions.

Low VOCs are an important consideration when buildings are occupied during a coating project. Luxury high-rises, schools and hotels have chosen NeverFade coatings for their low VOC content and low odor to minimize tenant inconvenience.

For more on NeverFade Coatings, visit neverfadecoatings.com.

Claims or positions expressed by sponsoring authors do not necessarily reflect the views of TPC, PaintSquare or its editors. NeverFade® is a registered trademark of APV Engineered Coatings, Inc., sold under a trademark license from Arkema, Inc., owner of the Kynar®, Kynar Aquatec®, Kynar 500® registered trademarks.

 

 
ABOUT THE AUTHOR
Lon Bauer, Product Development Manager, APV Engineered Coatings

Lon Bauer has over 26 years of expertise in the chemical and coatings industry. He has received two patents and has developed such commercialized chemistries as high-performance PDVF coatings under the brand NeverFade Fa├žade Restoration Coatings with Kynar Aquatec, specialty bonding primers, functional coatings, textile treatments, industrial inks, adhesives and heat seal coatings for OEM and field applications.

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