by Ron Joseph
What Does A VOC Content of 2.9 Lbs/Gal Mean?
Q. What Does A VOC Content of 2.9 Lbs/Gal Mean?
A. If a regulation says that the VOC of a coating must not exceed 2.9 lbs/gal, this is measured as the weight of the VOC in one gallon of the COATING. This does NOT mean that the solvent must have a density of 2.9 lbs/gal. There are NO solvents of which I'm aware that only weigh 2.9 lbs/gal. Most solvents used in paints and coatings, or for that matter we can apply this to the entire spectrum of solvents, have a density in the range 6.2 lbs/gal - 8.5 lbs/gal. There are very few solvents that fall outside this range. In fact, when the EPA writes its regulations it assumes that on AVERAGE solvents have a density of 7.36 lbs/gal. EPA fully appreciates that solvents have densities in the range I've just mentioned.
So what does the EPA mean when it regulates a coating at 2.9 lbs/gal? Simply put, if you were to weigh only the solvent portion in one gallon of coating, the solvent portion alone would need to weigh less than 2.9 lbs in the formulation. The EPA doesn't concern itself with which solvents you choose to use, provided that when you take a one gallon can of the coating, the solvent portion will weigh less than 2.9 lbs.
To be more specific, the one galloon of coating referred to in the regulation is measured at the point of application. For instance, if your coating has a VOC of 2.9 lbs/gal in the as-supplied can, and your customer adds additional thinners so that the VOC at the point of application is 3.2 lbs/gal, then the coating is out of compliance and an inspector has the right to issue a Notice of Violation (NOV).
In an earlier e-mail you asked for a substitute for mineral spirits. If you like the choice of mineral spirits in your formulation and can assure your customer that the weight of mineral spirits is less than 2.9 lbs/gallon of COATING, then you have satisfied your obligations.
I hope this clarifies the issue, and thanks for your question.