• 2017



WatercolorsThe use of waterborne automotive paint continues to increase as the legal allowable limits of VOCs (volatile organic compounds) continues to decrease. Rule 1151 is the law that started the regulation of VOCs and other automotive paint components that contaminate the air. This regulation was first introduced in Southern California where there was a large concentration of body repair facilities. In the early days of waterborne paint, there was strong resistance to this new paint, as one might expect. As the quality and application techniques of waterborne paint have improved, it has become more accepted in the body repair business. In this article, we’ll take a closer look at Rule 1151, waterborne paint and where it is in the industry today.

RULE 1151

Rule 1151 was introduced in 1987 and adopted on July 8, 1988. The purpose of the law “…is to reduce the VOC emissions, toxic air contaminants, stratospheric ozone-depleting compounds and global-warming compound emissions from automotive coating applications performed on motor vehicles, mobile equipment and associated parts and components.” While Southern California is by no means the center of the automotive manufacturing industry, the aftermarket industry thrives in that part of the country and a serious air quality problem existed.

VOCs are not banned by Rule 1151; rather, the amount of VOCs emitted by paint and clearcoats is regulated. For refinish basecoats, the amount of VOCs is limited to 3.5 pounds per gallon of paint. Typically, solvent-based basecoats emitted 5 to 7 lbs. of VOC. As you can see, the reduction in VOCs is significant. For clearcoat, the limit is 2.1 pounds of VOC per gallon.

In fact, there are 4 solvents that do not cause the formation of ground level ozone, which produces smog, that can be used in paint. These are acetone, ethyl acetate, tertiary butyl acetate and BCBTF. Many paint manufacturers have used these solvents to comply with VOC limits mandated by Rule 1151.

Currently, the prescribed limit of 3.5 pounds is in force through most of California and all of Canada. Rule 1151 is under consideration, however, in other sections of the U.S. Areas that are likely to be regulated are the Lake Michigan Air Directors Consortium (LADCO), which includes Illinois, Indiana, Michigan, Wisconsin and Ohio, and the Ozone Transport Commission (OTC) which includes Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, New Jersey, Delaware, Maryland, Vermont, New York, Virginia and Washington, D.C. And, parts of Texas might be in line to regulate VOCs due to poor air quality.

Waterborne paints came into the picture prominently with Rule 1151 for the simple reason that water-based paints do not contain solvents. But, it should be remembered, and this is a common misconception in the auto body repair industry, that Rule 1151 does not mandate the use of waterborne paint. The EPA’s objective is to simply regulate and monitor VOC levels in the atmosphere.


Waterborne paints are a practical, environmentally friendly alternative to solvent-based paint. Because water is the main ingredient, there are no solvents. There are several benefits to using this type of paint. First of all, and most obvious, is the dramatic reduction in VOCs (approximately 80 percent less than solvent-based paints). In simple terms, waterborne paints contain less VOCs than solvent-based paints, therefore, VOC emissions are less. The net result is cleaner air. Not only is this true of the outside air, but of the air inside your shop as well. The environment in which your painters work is now safer because they are not inhaling dangerous and smelly solvents.

Secondly, because water is the main ingredient, waterborne paints are safer. Such paints are much less flammable than the solvent-based counterparts, reducing the risk of fire. Due to this fact, you might get a break on your insurance rates. Also, waterborne paints are less toxic than traditional paints. If waterborne paint is spilled on the skin, clean up is done with soap and water.

Thirdly, waterborne paints can be applied with conventional and High Volume, Low Pressure (HVLP) spray guns. But keep in mind that your equipment must be kept very clean. That holds true, too, for the surface being painted. This is due to the fact that waterborne paint is not very tolerant of oil, grease and dirt. And because water is a corrosive material, plastic and stainless are recommended for internal parts of spray guns.



As we look to the future of automotive paint, it appears that waterborne paint is going to be a major player. One of the reasons for optimism is the fact that environmental regulations are likely to continue to lower the allowable levels of VOCs. Since VOCs aren’t a problem with waterborne paint, meeting the VOC standard becomes easier for the paint manufacturers and an easier choice for the repair industry. This is particularly true of basecoats. Another reason for a continued growth in the use of waterborne paints is the simple desire by many repairs facilities to go green.

As we look more into the future of waterborne paints, it’s very likely that the use of this technology will spread to primers, clearcoats and sealers. One of the drawbacks to using water in primers is the film thickness. Usually, primer thickness is 2 to 6 times thicker than basecoat. Since waterborne paint must fully dehydrate for proper curing, there have been questions in the industry as to its practicality. If you talk to some of the major paint makers, however, they believe that a complete waterborne refinish system, including undercoats and clears, is possible and likely in the near future. While meeting the VOC limit with exempt solvents instead of water is still practical, it seems inevitable that all related paint products will change to waterborne technology.

As waterborne paint use continues to spread, some of the myths that have surrounded its use are beginning to be debunked. For example, a common concern was that waterborne paint dries slower and is more difficult to apply than solvent basecoats. Well, the industry has found that with the proper air drying equipment, application times are on par with their solvent counterparts.

Another big myth concerns itself with the cost of waterborne equipment and the conversion to this type of paint. All of the major paint manufacturers — AkzoNobel, Axalta, BASF, PPG, Sherwin-Williams, Valspar — provide training and assistance at their training centers across the country to help body shops and collision centers make the transition to waterborne paint as seamless as possible. And, it’s being seen that once body shops see the benefits of waterborne paint, their long-term investment will pay off. It’s quite obvious that waterborne paint is here to stay.

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