Many of the products used during the collision repair process contain VOCs, including refinishing products, cleaners, spray corrosion-protection materials, and adhesives. Refinishing products are the biggest contributor. The VOC content of a refinishing product is basically the solvent in the product, and is measured in grams per liter (g/l) or pounds per gallon (lb/gal). VOC content may be listed "as supplied," which is the VOC content as it arrives at the facility, or "as applied," which would include the VOCs added by any thinners or reducers added before spraying.
Concerns over VOC emissions started with the EPA Clean Air Act of 1990. Different state and local jurisdictions instituted their own VOC rules for automotive refinishing based on the Clean Air Act. These rules ranged from requiring HVLP spray equipment to setting specific VOC limits for products used. The EPA put its first national VOC rule, the "National Volatile Organic Compound (VOC) Emission Standards for Automotive Refinish Coatings" into effect January 11, 1999 (see Figure 1). The "National Rule," as it is called, placed limits on the VOC content of refinish products used during the collision repair process and was an attempt to standardize VOC regulations across the country.
Because of localized air pollution problems, even stricter limits were adopted in southern California and then throughout the state of California in 2000.
California regulations can vary between counties. In California, the California Air Resources Board (CARB) sets a model rule that must then be adopted by over 40 individual air districts in the state. Some air districts may decide to place regulations that exceed the statewide model rule. The South Coast Air Quality Management District (SCAQMD) has the strictest regulations to date.
Beginning January 1, 2005 many of the mid-Atlantic states implemented California-like VOC regulations. Then in 2006, many of the New England states also adopted similar regulations.
Canadian VOC regulations are set by Environment Canada and are similar to the EPA National Rule. They are intended to be common to all parts of Canada, but are administered by individual provinces similar to how the CARB model rule is in California by the different air districts. As in the U.S., local regulations may be stricter than the Environment Canada regulations.
The EPA is currently considering changing the National Rule. The final draft of the new rule is expected to be finished by 2007 and fully implemented by 2011. The new National Rule would supersede any local regulations, unless the local regulations exceed the final language of the National Rule. It is expected to be similar to the current California "Model Rule," but until it is finalized anything is possible.
Beginning January 1, 2007, VOC regulations in the European Union nations are becoming much stricter than those currently in place in North America (see Figure 2).
Changes in refinish technology
VOC regulations are the single biggest driving force behind new automotive paint technologies. Automotive paint makers responded to the regulations by changing the chemistry of their paints. Conventional lacquer paints and basecoats in basecoat/clearcoat systems typically have a high-solvent content and as-applied VOC contents of more than 6 lb/gal. Clearcoats have been developed that have a much higher solid content and less solvent. Solvent-based, high-solid clears can have an as-supplied solvent percentage of 15- 40% by weight and as-applied VOC contents of less than 2.8 lb/gal with some as low as 2.0 lb/gal or less. The as-applied numbers may be higher depending on the amount of thinner added to the paint before spraying it.
Basecoat colors have posed a bigger challenge when it comes to VOC reduction. Currently there are no solvent-based, color basecoat systems that have an as-applied VOC content that meets the new European regulations. The paint companies have developed waterborne basecoat systems to meet these stricter regulations. Waterborne basecoats still contain some solvents as-supplied.
The big difference is in the amount and type of solvent, and that the thinner added to reduce the viscosity for spraying is water. With conventional solvent-borne basecoats, the as-applied VOC content is greater than the as-supplied VOC content. With a waterborne basecoat color, the as-applied VOC content is typically much lower than the as-supplied content. A waterborne basecoat color can have an as-applied VOC content of less than 120 g/l (1.0 lb/gal). Waterborne basecoat systems may be called water-based by some sources.
New technologies that reduce VOC content have also found their way into undercoats or primers used during the refinishing process. Waterborne technology is available in primers and sealers. Roll-on primers (see Figure 3), and a dual-cartridge primer (see Figure 4) are relatively new additions to the choices for undercoats. They are both very low in VOC content, containing less than 2 lb/gal, and require no additional thinners for application. An additional advantage that these products have is that they can be applied outside of the spraybooth and without the need to mask adjacent areas for overspray protection.
The EPA has a list of compounds that are considered VOC-exempt. New products are sometimes added to this list. In December 2004, tert-butyl acetate (TBAC) was added to the list. Individual states must now also add this compound to their list of exempt products. As of March 2006, 34 states have done so. In the SCAQMD, TBAC use is presently only approved in undercoats. These exempt solvents may lead to new solvent-borne refinish materials in the future that are VOC compliant even in areas with very low limits.
The good news is that implementation of VOC rules are typically phased in slowly over time, giving collision facilities time to adapt to the new technologies in paint products. Waterborne paints are more sensitive to temperature and humidity differences than solvent-borne products, and may require additional equipment and new spray booth technologies to get them to dry quickly and consistently. Current rules place more of the burden on the paint makers to supply compliant products than on the repair facilities themselves, but this doesn't exempt the facility from knowing and following any regulations in their area.
Paint makers and local paint suppliers are a collision facility's best resource for determining which products are compliant where their facility is located. European refinishers are soon going to have to adopt waterborne technology to meet the stricter VOC limits going into effect there. The North American market has time before this change occurs, and exempt solvent-borne products may or may not become available to the market before VOC regulations require their use. Facilities in the SCAQMD of California have more reason to take action than anywhere else in North America.
This Advantage Online article first appeared in the I-CAR e-newsletter, which is published and distributed free of charge. I-CAR, the Inter-Industry Conference on Auto Collision Repair, is a not-for-profit international training organization that researches and develops quality technical education programs related to collision repair. To learn more about I-CAR, and to subscribe to the free e-newsletter, visit http://www.i-car.com or contact I-CAR Marketing Communications Specialist Brandon Eckenrode at Brandon.Eckenrode@i-car.com.