While concentrations of volatile organic compounds (VOCs) are consistently higher indoors, they also are a concern outdoors, where they can lead to adverse health effects. Once in the atmosphere, VOCs react with oxygen to produce ozone, a key component of smog.
VOCs from coatings can be a nuisance to contractors, building occupants, and passersby. Moreover, they can be drawn into a building through open windows and HVAC (heating,
ventilation, and air conditioning) systems, compromising indoor air quality.
Why Do Coatings Contain Volatile Organic Compounds?
VOCs in solvent-borne coatings usually come from the solvents themselves. Solvents offer an efficient and low-cost means for dissolving and dispersing raw material components. They also evaporate rapidly, which shortens 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.
Water can replace solvents in coatings to reduce emissions and VOCs, but these coatings generally still contain a small percentage of co-solvent to help the process. VOCs in a water-based coating are usually found in the resin or binders, thickeners, certain additives such as defoamers and surfactants, and pigments. It is estimated that 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, above and beyond the VOCs contained in the solvent.
In general, higher concentrations of VOCs are found in extreme-durability solvent-borne polyurethane and acrylic topcoats and pretreatment wash primers, where they run in the 5.0-6.5 pounds per gallon (600-778.9 g/L) range. Low-VOC water-based coatings typically contain less than 100 grams per liter, while 5 grams per liter is considered “very low” or “zero.”
APV’s chemists who formulate water-based NeverFade® coatings understand the characteristics of the polymer chemistry, impact of rheology modifiers, and appropriate co-solvents to optimize a continuous film formation without the need for solvents.
VOC Regulations
While few regulations or standards exist for VOCs in outdoor environments, states such as California are taking a more aggressive approach.
The South Coast Air Quality Management District (SCAQMD) in California adopted (and has subsequently amended) Rule 1113 to tackle area source emissions of paint and coatings. It is the most comprehensive and strictest restriction in the United States. Many other states have adopted it, and many manufacturers have chosen to follow it as well.
With less than 50 g/L of VOCs, NeverFade® Original Topcoat is one of the very 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 is capped at 380 g/L). The topcoat’s complementary primers also contain less than 50 g/L of VOCs.
Water-Based PVDF Coatings Blend Safety and Performance
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, extreme weatherability, and color-retention properties as solvent-based coatings. This is no longer the case thanks to the introduction of Kynar Aquatec®, a polyvinylidene fluoride (PVDF) water-based resin emulsion. This tough engineered thermoplastic has a 20+-year demonstrated record of performance in extreme conditions and serves as the binder in APV’s water-based NeverFade® coatings.
Low VOCs are an important consideration when buildings are occupied during the coating project, especially when air-handling units bring outdoor air inside. For example, when owners of a luxury high-rise condominium in Florida wanted to improve the curb appeal of their building with a refresh of its exterior coatings, they chose NeverFade® Coatings for their low VOC content and low odor that would keep tenant inconvenience to a minimum. Schools and hotels have made the same purchasing decisions, allowing coating projects to proceed and business to be conducted as usual while buildings are occupied.