Sealers, coatings, adhesives, and strippers made with volatile organic compounds (VOCs) are cheaper and in many cases perform better than the alternatives. But with regulations governing VOCs becoming stricter, and with water-, citrus-, and soy-based materials gaining ground, choosing which product to use can leave a concrete surfaces’ contractor in a bind.
VOCs are volatile, meaning they evaporate rapidly into the air (basically, they boil off), usually at room temperature. But the VOC term is actually a legal definition created by environmental regulatory agencies to classify chemicals that with sunlight can produce ozone, leading to smog. And while most VOCs in the environment are released naturally by trees, the number one man-made source is solvents. So that’s where regulators have focused.
VOCs began to be regulated in the U.S. in the 1970s. The original target was paints which evolved to include concrete coatings under the classification of architectural and industrial maintenance (AIM) coatings. The EPA limits on VOCs in AIM coatings apply to the entire country while certain states or regions have adopted more stringent requirements. To say the regulations are complicated is an understatement.
California, Canada regulations
This is especially true in California where the entire state is under the California Air Resources Board’s (CARB) Suggested Control Measures. These VOC requirements are broken down into more than 100 different products, such as coatings, sealers, stains, and waterproofing, each with different limits.
Then there are 25 different air control districts within California, each with slightly different requirements. Recently, a new California Green Construction Code took effect with reduced VOC limits for most of the state.
There also is the Northeast Ozone Transport Commission (OTC), which has set standards that have been adopted by 13 northeastern states. These requirements are similar to the CARB rules but with slightly higher limits on 55 categories of AIM coatings. In 2010, all of Canada adopted regulations similar to the OTC requirements.
“There is pressure to keep nudging the numbers down,” says Dwayne Fuhlhage, director of regulatory affairs for Prosoco, Lawrence, Kan. “But it gets more difficult because the products still have to work. Continuing to reduce VOCs reaches a point of diminishing return. In California, there’s not a lot of VOC left in the products.”
Designating the VOC levels in a product is basically left up to the manufacturers. As you might imagine, sometimes they use regulation loopholes to make their products appear better than their competitors. For one thing, there are VOCs that, for various reasons, are exempt from the VOC rules.
“Exempt volatile organic compounds (such as acetone, T-butyl acetate, or PCBTF) are used in the same way as standard VOC solvents but do not count as a VOC because of their exempt status,” says Doug Bannister, owner of The Stamp Store, Oklahoma City.
Another source of confusion is that the VOC limit for a specific product is based on its intended use, which can be as simple as the marketing claims made by the manufacturer. Products that have multiple uses are required to meet the most stringent requirements.
“The regulatory category definition is as important as the category name,” writes Fuhlhage in a Prosoco white paper on VOCs. “A film-forming water repellent marketed specifically for concrete and masonry would not be held to the category limit for a flat paint.”
Indoors versus outdoors
Also important is the difference between VOC materials used indoors and those used outdoors. The VOC requirements are intended to reduce smog, so they apply to all products used in a certain area. But for indoor use, the objective is to determine a product’s impact on indoor air quality (IAQ). For this, the limits are found either in LEED or in the International Green Building Code. For example, in LEED for New Construction (commercial buildings), architectural coatings must have a VOC content less than 250 grams/liter.
But in reality, VOC requirements are not that meaningful for indoor air quality. For that, manufacturers would have to have a vacuum chamber emissions test conducted by an independent testing lab. “They apply the coating to the concrete and put it in a chamber that models an office or school in terms of typical air flow rate and temperature and humidity,” says Fuhlhage.
“At day 14, they start testing and then create a report on the specific chemicals that show up in the air. Long term, I see green building standards having these emissions standards as the primary criteria for indoor use products, but each emissions test costs about $3000 and every company has to test every product and retest every time there’s any formula changes.”
And in today’s drive to make everything green, many projects will specify LEED requirements on products even if there is no intention to seek LEED certification. “I’d say 60%to 70% of the low VOC products we sell are for use in buildings where there’s no effort to get LEED certification,” says Fuhlhage. “It’s a case of higher sensitivity, especially for a school or hospital. They don’t want complaints.”
So with all of the concerns, why are VOCs used in the first place? “Volatile organic compounds (solvents) are used in coatings to lower the viscosity for better flow, usability, penetration, or to dissolve certain types of resins such as acrylics,” says Bannister. So we need some sort of solvent, and water simply does not dry fast enough for most uses.
“In water-based coatings, water is the main solvent replacement, but the product usually also contains a VOC solvent or an exempt VOC solvent to aid in film development,” Bannister adds. “New water-based coatings technology has improved such that many are equivalent or superior to solvent-based coatings, however, normally with a very high price tag.”
This price differential is significant. Many VOCs are byproducts of petroleum refining. Because they are basically waste products, the price can be kept quite low. New products, such as soy-based solvents, find it difficult to compete on strictly a cost basis.
“I don’t think people would consider switching to soy-based products without government regulation,” says Dan Brown, general manager of Franmar Chemicals, Bloomington, Ill., that makes soy-based strippers. “It wasn’t until the laws changed that users and manufacturers started looking at changing products. Our Bean-e-doo (a mastic remover) is an affordable product at about 11 cents/square foot. But you can do the same job with xylene for 5 cents/square foot.”
To justify this extra expense there must be other factors, such as worker safety and green benefits. Brown recalls a worker using a soy-based stripper who threw his cigarette butt right into the residue, an explosive situation with VOC-based strippers.
The soy-based products use an ester distilled from soy bean oil—a solvent that is equivalent to the biodiesel sometimes used to run internal combustion engines. “It’s a solvent and it behaves like other solvents, but it evaporates very slowly,” says Brown. To make it work, it has to be removed because unlike VOC solvents it doesn’t evaporate. “We have to make sure it is cleaned up properly or else there’s a residue that will prevent adhesion of coatings or floor coverings.” That cleaning is done using water in a very tightly defined procedure.
Solvents are with us to stay, and probably so too are VOCs. The rules will continue to evolve and tighten, so be sure to look closely at manufacturer claims and get the best products for your application and customers.
A version of this article first appeared in Concrete Decor, October 2010.