If you think spraying finish is a complex task best left to professionals willing to toil through impenetrable clouds of overspray, think again. High-volume low-pressure (HVLP) spraying is a relatively simple and affordable way DIYers can achieve a top-quality finish on a variety of projects.
HVLP spraying eliminates many disadvantages of conventional high-pressure spraying, such as inefficient material transfer (bounce back and overspray) and finish defects caused by moisture and oil in the air line. This means you’ll make less of a mess, conserve material and produce smoother, cleaner finishes. In fact, several states have air-pollution laws that allow only HVLP spraying for commercial finishing operations.
What you can spray
HVLP sprayers are intended for applying high-quality finishes to furniture, cabinets, interior woodwork, crafts projects and, with the right unit, even cars and boats. They’re also suitable for some exterior finishing jobs, such as spraying stain. However, the power of the sprayer relates directly to the size of the projects you can tackle.
Besides the scale of the item to be finished, the material you want to apply also determines the power needed. For instance, more power is required to spray heavier-bodied finishes, so only the most powerful HVLP units are capable of spraying latex house paint. (An airless sprayer is a better choice for exterior house painting.) Almost any HVLP unit can spray stain, lacquer and varnish, but more power is required for some waterborne finishes and oil-base paint.
How it works
An HVLP spray gun applies finish at relatively low pressure (4 to 10 psi); about one-tenth that of a conventional high-pressure spray gun (25 to 80 psi). This means the finish hits the work at a much slower speed, so more of it sticks to the work rather than bouncing off and creating a fog. Depending on the finish and the gun being used, as much as 90 percent of the finish will stick. That’s almost twice the efficiency of a high-pressure gun.
Two types of HVLP guns are available: turbine-driven guns and compressor-driven guns. Sprayers that use compressed air are called conversion guns or compressor HVLP guns. They convert high-pressure air coming from the compressor to low-pressure air in the gun. Compressor HVLP guns typically require a large compressor (at least 3 hp) and line filtration for moisture and oil. These guns are preferred in industrial settings because they’re more economical to run and can apply finish more quickly.
While both turbine and compressor systems work well, turbine units (which are essentially vacuum-cleaner motors) are generally a better choice for DIYers and small-shop professionals. They deliver warm, dry, filtered air to the gun — ideal for most DIY finishes. Turbine units are also portable, so you can spray anywhere.
You may already be familiar with the turbine sprayers made by Campbell Hausfeld and Wagner that are sold at many home centers for about $200. These units work well for small-scale craft projects and small to moderate-size pieces of furniture. But more powerful turbine units (starting at $400) are available from these companies as well as manufacturers such as Apollo and Fuji (see SOURCES) that cater to serious DIYers and professionals. These sprayers deliver finish more quickly for large projects and are better quality than entry-level sprayers.
Smaller HVLP turbines are usually two-stage designs. (The motor employs two blower fans.) Larger sprayers have three- and four-stage turbines. The more turbines, the greater the air volume — and the higher the cost. Three-stage turbines represent the best balance of power and price for DIYers. These units deliver finish quickly enough that the first areas you spray won’t dry before you’re done, but they’re slow enough to afford plenty of control for a novice.
Advanced Machinery Imports
(302) 322-2226, www.advmachinery.com
Wagner Spray Tech