Powder Coating vs Liquid

Powder Coating vs Liquid. One of the things we powder people lose sight of is what alternatives exist for the industrial coater. We get our knickers all twisted when we consider the toxicity profile of one of our cross-linkers or when we explore which personal protective equipment (PPE) to use when applying our zero-VOC, HAPs-free coating technology. To keep things in perspective, let’s look on the other side of the industrial finish spectrum of technologies – the solventborne paint.
We can start with hazardous air pollutants (HAPs). The United States Environmental Protection Agency (U.S. EPA) defines them thus: “Hazardous air pollutants, also known as air toxic air pollutants or air toxics, are those pollutants that cause or may cause cancer or other serious health effects, such as reproductive effects of birth defects, or adverse environmental and ecological effects.” They currently count 187 compound categories as HAPs, including many organic solvents. (ref:http://www.epa.gov/ttn/atw/orig189.html) Many of these compounds are typically used in liquid paints and include:
If your finishing system is sophisticated enough to include costly oxidizers (or scrubbers) to convert solvent emissions to carbon dioxide and water (an expensive process to operate) so you don’t pollute, then you still have to examine the operations costs of using solventborne paints. The oversprayed liquid paint accumulates as a thick sludge that has to be disposed of. No one seems to have a good answer as to how to handle this hazardous waste product (see: www.finishing.com/0800-0999/816.shtml). And if there is no easy solution, then disposal costs can be enormous.
Another issue to face is the transportation, storage and handling of flammable, toxic materials. Department of Transportation requirements for transporting solventborne paints are onerous, which makes transport costs prohibitive. Once the material arrives at your receiving dock, it has to be handled by trained personnel and typically winds up in a storage area that looks more like a bomb shelter. These “paint kitchens” are adorned with National Electrical Manufacturer Association (NEMA) Class 1 electrical fixtures and switches, which cost five to ten times as much as non-explosion proof counterparts. Not only does this add up to higher operating and capital equipment costs, but insurance premiums are invariably higher for solventborne finishing systems.
If you’re not convinced yet, think about quality. Solventborne coatings are difficult to apply as thick films (sags, runs, solvent-popping, etc.) and therefore seldom approach the abrasion resistance, durability or corrosion resistance of a thicker film powder coating.
Even if you are ambivalent about toxicity, air pollution, hazardous wastes, flammability and durability, the bottom line is this: Solvenborne paints offer less overall value compared to dry, non-toxic powder coatings. So, if you’re wondering if solventborne coatings will make a comeback…let’s hope not.