HVLP Recommendations

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

1. Startup cost is lower due to compressor cost.
2. Portability, turbine guns may be easily used in almost any location with power and ventilation.
3. Turbines have a similar noise level to a vacuum — gee what a surprise — while compressors in the same room are loud.
4. A turbines take less space than a compressor, and is easily stored when not in use.

Expansion gun pluses

1. Expansion guns are readily available and come in a variety of sizes. Turbine systems have very few available guns.
2. Parts are readily available for the expansion gun, in particular, air caps. Regardless of what gun you select, check air cap availability and price before purchase. Most of the time a medium tip and cap is supplied, however, when spraying light or vicious materials a tip and cap change may be required. Prices for tip and cap can vary from $15 to $200 per set.
3. Expanding air causes a temperature drop within the gun while turbine air is warmer than ambient. Warmer air flashes solvent at the tip which may cause application issues. Please note that this is a minor point.
4. An expansion gun is fed air by a common air hose available at Home Depot. Turbine hose is hard to come by.
5. Size and weight of the turbine hose is fatiguing. This is very significant on large items or while spraying large panels.
6. Again due to the large turbine hose size, spraying flexibility is reduced and the chance of hitting the hose in a freshly sprayed surface is increased.
7. Parts and repair of most compressors are available at many shops even Grainger. Turbine, good luck, go to the manufacturer.

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.