This Old House Magazine: Choosing & Using Paint Sprayers They can lay down everything from latex to lacquer—but no one sprayer can do it all By Clayton DeKorne
From This Old House Magazine
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Cup Gun
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Diaphram Pump
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Piston Pump
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Air-Compressor Gun
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High Volume/Low Pressure (HLVP)
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Paint sprayers have an obvious advantage: They can spread paint, stains, and clear finishes faster than any brush or roller. But just as important is their ability to apply an even coating to uneven surfaces like window shutters and stair balusters—fertile ground for brush drips. And because sprayers atomize liquid into a fine mist, they can create a mirrorlike finish on cabinets or furniture where even minor brush marks are unacceptable.Sprayers aren't always the best choice, though. Small jobs seldom justify the tedium of cleaning them (sometimes a simple can of spray paint will do), and a brush is better at giving you control where neatness counts. But when a sprayer makes sense, success depends on choosing the right one for the job and mastering a few techniques. Start by considering what you'll be spraying and what finish you'll use—sprayers vary a lot in the thickness of the finish they can handle, the amount of paint they deliver, and the overspray they produce, among other factors. Generally, there are two categories: sprayers that use air to atomize the finish and airless sprayers. Both have advantages and disadvantages, and there is a wide range of quality and price within each category.
Picking the Right Gun Tip
Many spray guns have interchangeable tips. Which one you choose depends on the coating you're applying and the size of your work piece. Manufacturers use a numbering system that's easy to decipher: The first digit refers to half the width of the spray, or fan, from 12 inches away, and the rest of the number denotes the size of the opening in thousandths of an inch. For example, a "517" has a 10-inch-wide fan and a .017-inch orifice. Below are general guidelines for orifice sizes matched to coatings, but consult the manufacturer's literature.
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Preparation
Mask off everything (windows, shrubs, cars) with taped drop cloths or plastic to shield from overspray, and protect yourself with a respirator, goggles, and hood. For the smoothest finish, thin down the coating. Painting contractor John Dee prefers quick-evaporating naphtha for oil-based finishes, which helps the paint dry before it sags, and latex paint thinner for water-based coatings.
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Fan Settings
Some guys have an adjustable tip, which allows you to change the size and shape of the fan of paint it puts out. Test your gun before spraying to find a shape and volume that helps you control the overspray but still gives efficient, effective coverage.
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Hand Position
Point the gun straight at the surface, holding the tip about 12 inches away. If the gun is angled, the spray will be thicker on one side than the other. Move your arm, not your wrist, to keep the gun straight.
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Spraying Motion
To avoid buildup, start spraying off one side of the work piece and don't release the trigger until the spray has passed the other end. If you're painting a wall or other surface with no edge, start moving your arm before pulling the trigger, and release it before you finish the motion. Overlap each pass about an inch to avoid sags or thin spots.
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The Box-Coat Technique
John Dee builds up thin coats of finish using a spray pattern he calls the "box-coat technique," in which he lays down the paint first horizontally, then vertically. This method works especially well on paneled doors and cabinets. Orient the tip so the fan sprays in a vertical line for the horizontal pass, then turn it 90 degrees for the vertical pass.
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Cleanup
Paint that has dried in a sprayer's hose or gun can cause clogs that make the sprayer sputter and spatter. Immediately after use, remove the tip and soak it in the appropriate solvent (water for water-based coatings, thinner for oil-based), rinse out the cup with the same solvent, then run more solvent through the lines and cups until all the paint is flushed out and the solvent runs clean. Caution
Airless sprayers operate at extremely high pressure. If your finger (or any part of your body) gets too close to the tip, paint can be injected under the skin. If this happens, seek emergency treatment immediately, and be sure to inform the care provider you have an injection wound. The injury may not look all that serious, but most coating materials contain dangerous toxins that must be removed.
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__________________________________________Resources:
Cup gun
Wagner Power Painter
Wagner Spray Tech Corporation
Minneapolis, MN
800-686-8525
www.dcmsoft.com/wagner Diaphragm pump
#PS250K by Campbell Hausfeld
Harrison, OH
800-626-4401
www.chpower.com Piston pump
Titan 640i by Titan Tool Inc.
Franklin Lakes, NJ
800-526-5362
www.titantool.com HVLP
USA-HVLP 300S
Apollo Sprayers Inc.
Vista, CA
888-900-4857
www.hvlp.com
available through Advance Machinery
Newcastle, DE
302-322-2226 Our thanks to
Chuck Scaminace
Sherwin-Williams Company
www.sherwin-williams.com
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