On a recent visit to Charley Hutton's Color Studio, Charley Hutton gave us a working tour of Envirobase High Performance, PPG's line of waterborne basecoats. Though the information applied specifically to the paint, every so often he'd interrupt himself to reveal handy methods and potential pitfalls that escape most enthusiasts. "You could probably do a story about nothing but these little things," he observed at one point. That inspired us. So here we are.
What follows is largely a collection of very basic tips and tricks. Though some are perennial favorites in the paint-story world, they bear repeating for several reasons. Obviously this information serves newcomers. But probably more importantly, if not so obvious, it benefits seasoned professionals just as well. Over the years we've seen veterans violate a few of these simple rules. Old habits die hard; bad habits die harder.
Anytime is a great time to establish new habits, but right now may be the very best time to reevaluate old ones. Until now, many of us have gotten away with various sins, but our happy luck may be coming to an end. Though easy to use, the future generation of finishes won't forgive the same violations that paints of yore did.
Lots Of Clean, Dry Air
Air supply isn't the most critical element to spray paint. However, we treated it with priority because it's the first thing would-be painters should consider when planning a shop.
High-volume, low-pressure (HVLP) spray guns revolutionized paint transfer rates. High-pressure guns of yesteryear blasted paint at such intense velocity that more than half of the materials left the gun as a dense fog that ended up on everything but the target (Graco, makers of Sharpe guns, estimates about a 25-30 percent transfer rate for non-HVLP guns). By reducing the pressure and increasing the volume, however, modern HVLP guns can transfer at least 65 percent of all materials to the intended target (some achieve even greater transfer efficiency).
That increased transfer efficiency reduces material cost and pollution, but it requires one thing: lots of air. According to The Eastwood Company, compressor ratings tell only a part of the tale. Compressors, like engines, are rated when new and under ideal conditions and we all know what age does to mechanical things. Furthermore, every component in the system—pipe, elbows, regulators, filters, hose, and even fittings imposes a volume restriction. Again, according to Eastwood, if a system's air supply can't deliver enough air to a volume-sensitive tool like a paint gun, the finish will suffer.
Proper technique has always called for clean and dry air, but the new breeds of finishes are even more vulnerable. It goes without saying that the tiniest drop of oil introduced into the paint stream will obliterate a finish. Though waterborne systems rely on water as a transfer medium it goes without saying that an extra drop of water can throw the ratio out of whack … and wreck a finish.
The Foundation Is The Finish
Paint has always been notoriously thin, approximately 2-3 mils or roughly the thickness of a human hair. Though seemingly sparse, that's sufficient to fill 400-grit sanding marks.
Modern paints aren't so forgiving. As we revealed last month, waterborne basecoats achieve about 0.5-mil coverage. That's 15-25 percent of what older solvent-based paints could achieve. They rely on immaculately smooth surfaces. While Hutton says we can get away with 400-grit prep with solvent-based paints he advises at least 600-grit for waterborne finishes.