Ask the Expert Question-and-Answer Archive

by Ron Joseph

November, 2001

Calculating VOC Emissions From Curing Ovens

Q. I am trying to quantify VOC emissions from a curing oven. I have manufacturer's technical data sheets that show time to tack free dry, total cure tome, and such. These are qualitative descriptions and do not describe remaining (residual) VOC content. I am hoping to find emperical information showing residual VOC content vs time. Everyone agrees that the majority of the VOCs evaporate quickly, and that the residual VOC vs Time graph would look like exponential decay, but no one has been able to provide numbers. I need to do this to obtain an air emission permit. I know this information is dependent on several variable and is different from one coating to another, but if I could find one example it would be very helpful. Any information or other sources that you could provide would be appreciated

A. Thanks for your question. The answer is much simpler than you might expect. You do not need to conduct any tests on cure time, retention of the paint in the oven, etc. All you need to do is check with your vendor for the VOC content as measured per EPA Method 24. Every paint vendor should already have this information, and in all probability it has already been recorded on the MSDS.

The key issue is that the VOC MUST be determined by EPA Method 24, and NOT by adding up the volatile ingredients in the paint formulation.

In EPA Method 24, the percentage weight of volatile ingredients is conducted by following ASTM 2369, of which your paint vendor is familiar. This test is conducted at 230oF for one hour. EPA is fully aware that YOUR coating (regardless of the vendor, coating type or formulation) will probably be cured at 250oF-350oF for some period of time, such as 8-30 minutes, but to "level the playing field" all coatings are tested in the above manner.

Here then is the solution to your problem. Determine how many gallons of coating you apply (use), and multiply by the VOC content as provided to you by your vendor. That's it. No further testing is necessary.

Even if a small amount of solvent should be retained in the coating after it leaves the curing oven, EPA will not allow you to claim credit for it, so don't waste your time with expensive testing.