BJ Tanner replies: From my viewpoint an expansion gun used on a standard compressor is the best alternative for many reasons. First, it is the method used by commercial automotive refinishers and almost all commercial wood finishers. This puts a wide variety of suppliers for both guns and parts at your fingertips. All of my spraying supplies come from automotive shops, not woodworking suppliers. Second, Due to the wide availability, inexpensive guns that work well are readily available. Third, if you acquire a reasonable compressor you may also use pneumatic tools. After using a pneumatic sander you will never want to return to electric power again. But it all comes down to pluses and minuses and how it fits your application.
Turbine gun pluses
Expansion gun pluses
If you do decide on a compressor type gun, start with a good compressor. Compressor should exceed 10 CFM (cubic feet per minute) at 120 PSI. Spend a couple of extra bucks and opt for a 100% duty cycle compressor — most big box stores sell 50% duty cycle compressors. Good used compressors are available at a reasonable price. My commercial seven horse compressor cost $350 and will most likely out last me. I made the decision to use a compressor while still woodworking as a hobby. I placed the compressor in the garage and plumbed the basement with pipe. This kept the noise in the garage and also gave me the added benefit of using air tools to fix the cars.
Chris Kovacs replies: I have no experience with turbine systems and have only used HVLP guns connected to a compressor. For someone starting out, I would recommend a relatively inexpensive gravity cup HVLP gun. They can be purchased for about $120.
These guns spray very nicely and can be adjusted for a range of different finishes. I use the gravity guns for spraying shellac, conversion varnish, waterborne clear finishes and primers. The gun is easy to clean and maintain. The cups typically hold a quart or less of fluid. I usually fill my gun with only about 3 cups of finish as they can become heavy and tiresome to use after a while though. These guns are ideal if you only need to spay a small amount of finish. You will however need a sizable compressor for these guns. I operate the HVLP guns using a 60 gallon 5 hp compressor. You will need to check the CFM requirement of the gun and make sure you have a compressor that can meet the air flow requirements.
If you are planning to do a lot of spray finishing, the next step up is a pressure pot system. These systems can cost $1,000 or more but produce a better quality finish than gravity cups, have a capacity for 2.5 gallons or more of finish and since the liquid sits in a pressure pot on the floor, the gun weighs much less and there is significantly less strain on your arm while finishing. The pressure pot systems are best suited for the professional cabinet and finishing shops.
Eric Johnson replies: I use an HVLP gun with my compressor and I am very happy with the outcome. The added benefit of this arrangement is I have a compressor for other jobs around the shop. The turbine system is not only very expensive but that is all it is good for. So for me it makes more sense going with an HVLP gun with a compressor.