|What in the world is "VOC?"
After seeing the term "VOC" misused lately I thought a little "primer" if you’ll pardon the pun was due.
"VOC" stands for Volatile Organic Compound. Basically it is solvents deemed dangerous to our atmosphere (more on that later) that flashes off during and after application. It is measured by "pounds per gallon". You will see references like "4.6 VOC" on many products. Meaning that the product has 4.6 pounds per gallon of VOC per sprayable gallon. When you see this on the front of the label it usually refers to "as applied" or "sprayable", with all components mixed. If you look on the ingredient label you will likely see different numbers, these are referring "as packaged". That would be the VOC in the can you are looking at, not "as applied" with them all mixed.
Theoretically if you were to mix the product with "4.6 VOC" as applied with all it’s components and set the can out in the sun, after it fully flashed off and there was just hard stuff in the can, it would weigh the 4.6 less. That 4.6 pounds went up into the atmosphere. It wouldn’t happen exactly like that, for a number of reasons but that is the basic theory behind the VOC measurement.
One of the reasons this wouldn’t happen is the fact "not all bad stuff is created equal". Remember, I said "VOC" is the stuff that goes UP into the atmosphere? Well, the stuff that goes DOWN isn’t VOC is it? Not according to the powers that be in our Federal government. Some solvents are "VOC exempt", meaning they have ZERO VOC.
The most obvious would be water, it is used in a number of "waterborne" and "waterbase" products. I would make sense to the layman that water is harmless (relatively) in this context. However, there are many other "VOC exempt" compounds such as acetone and chlorobenzotriflouride (oxhaul sp? trade name). Yep, that’s right, acetone is exempt, zero VOC. These two particular solvents are very heavy, they don’t go UP, instead they go DOWN as they flash off. One day they will likely be banned as well because they contaminate our ground water! But for the time being they are a freebie in the automotive paint industry.
I am sure I am about to loose you so let me get to the point. VOC or the lack of has NOTHING to do with the level of danger in the use of a product, NOTHING. I’m sure we can agree acetone is some nasty stuff, yet it is VOC exempt. Don’t let some one sell you a product that is low or zero VOC on the pretense it is "safe". Even without the solvents, there is all kinds of stuff that is in the paint. I don’t care if it is waterbase house paint. If you are spraying it, atomizing it, there are particles of the stuff in the air. Do you want to coat your lungs with particles of the "Crescent Moon" off white you are painting your living room in?
Ok, if I haven’t put you to sleep and would like to know more, here goes.
Oxhaul for instance is a very heavy solvent at 9.8 pounds per gallon. That is not only 9.8 lbs of free VOC, but it actually "lowers" the VOC of a given product, here’s how.
If you had a primer that was 10 pounds VOC as packaged and reduced it 1:1 with Oxhaul it would then have a sprayable VOC of 5.1 VOC effectively, half of what it was. This is the only reason lacquer primer is still on the market, reduced with acetone 1:1 it is compliant. Reduced with lacquer thinner it is not even close. I am referring to the "National Rule", in many areas there are local VOC regulations that restrict it’s sale.
High Solids hardeners for instance many times are zero VOC! So, you have a quart of hardener, with zero VOC, it is full of isocyanates, but it is VOC free. So again, that quart of VOC hardener will "lower" the VOC of the sprayable clear, yet make it MORE hazardous to YOU.
You will see all kinds of goofy mixing ratios like 4:1:1:1 with the first "1" being a urethane reducer and the second "1" being an exempt reducer. This is done to keep the VOC down and the product compliant. When the "National Rule" went into effect back in 1999 (?) you saw all kinds of goofy mixing ratios all of a sudden for this reason. If they didn’t add some exempt solvents (or a LOT of exempt solvents) the product would have been dead on the shelf. So they had to MAKE it compliant to keep selling it.
With these heavy solvents it is imperative that you don’t bomb on the product and give it full flash time. Many primers use acetone to keep the VOC down, if you bomb it on thinking it is "only the primer" you are going to have trouble with the product no curing. I have seen super low VOC products that were mixed correctly (at least I think they were) that were still WET days later because of this.
As a rep I dealt with this stuff all the time and in fact I worked markets in both VOC regulated and no VOC regulated before the National Rule. It has been a few years so I am certainly more than a little rusty in the area. As long as the point is clear VOC is NOT a gauge of danger to YOU, I don’t really care is some minute detail is not totally accurate.
You need to protect yourself, none of these products are "safe", NONE of them.