The Truth About Claims of No VOCs
The original definition of a Volatile Organic Compound (VOC) was any organic compound with a vapor pressure higher than 0.1 millimeter of mercury, allowing it to enter the atmosphere quickly and easily. VOCs typically lower the viscosity, or thickness, of the coating chemicals and enable the chemicals to be more easily sprayed. Most solvents meet the original definition of a VOC–entering the atmosphere quickly and easily–but not all solvents are VOCs, something not commonly known
An exempt solvent is a solvent compound that by all characteristics is a VOC according to the original definition but has been exempted from the law for some reason. Unscrupulous coating suppliers can incorporate either non-VOC solvents or even exempt solvents into their formulated products. By definition, they now have a non-VOC product. Some companies will sell a product labeled as Zero VOC that contains non-VOC solvent, but never disclose that information on the label. Zero VOCs does not mean no solvents, and the product label may not tell the whole story.
By using a non-VOC solvent to disperse the resins, formulators can use much cheaper resin raw materials. On the other hand, true 100% solids resin materials, while more expensive, have a low enough viscosity to be cold sprayed without the use of any type of recognized solvent. Beware of the phrases Zero VOCs or No VOCs. They do not automatically mean solvent-free or no solvents.
Investigate further into whether a coating, in fact, has no solvents, versus only no VOCs, by learning more about some of the solvents defined as “exempt solvents” in the United States. These include: Acetone, Methyl Acetate, Volatile methyl siloxanes, Parachlorobenzotrifluoride (PCBTF), Methylene chloride, and a wide range of chlorofluorocarbons. You may find these listed either on a side panel of the packaging or on the Material Data Safety Sheet (MSDS). When you request a MSDS from the product manufacturer, it should always be made available to you. Some manufacturers provide this information on their websites