Paint Sprayers

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. 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. Click through the slide show at left to see a range of sprayers, their uses, and the pros and cons of each.

Cup Gun

Pros: Inexpensive (quality models start at $100); better ones have enough pressure (1,800 to 2,400 psi) to handle thick latex paints as well as stains. Cons: Don’t have power or capacity for big jobs; least expensive models (1,400 to 1,600 psi) sputter and can’t handle thick paint. Best for: Craft projects and small painting jobs. Similar to shown: Wagner power products 305 painter sprayer; about $63; amazon.com

Diaphragm-Pump

Pros: Will handle most paints without thinning and spray large areas efficiently; easier to maintain and less expensive than piston-pump sprayers (quality machines start at $250) Cons: Overspray (known as low “transfer efficiency”)—sometimes less than half the paint ends up on the work; not good for interiors. Best for: Decks, siding, or house painting. Shown: Campbell Hausfeld airless paint sprayer; about $350; amazon.com

Piston-Pump

Pros: Most powerful sprayer type; can spray high volumes of any coating quickly Cons: Overspray; more complicated maintenance; most expensive (typically over $1,000)—renting for about $70 a day is a better option. Best for: House painting. Shown: Titan Tools piston-pump; about $1,300; jnequipment.com

Air-Compressor Gun

Pros: If you already own an air compressor, all you need is a gun and a hose (about $125 for good-quality ones); produces very smooth finish. Cons: Has the greatest overspray of any rig; can’t spray thick paint. Best for: Finishing furniture and cabinets—anything you can isolate in a closed spray booth. Similar to shown: Wagner conversion gun; about $150; northerntool.com

High Volume/Low Pressure (HVLP)

Pros: Good for interior use since low pressure (3 to 10 psi) creates little overspray and a very smooth finish; mid-range cost ($200 to $500 for better home-use models). Cons: Can’t spray thick paint. Best for: Finishing inside trim, cabinets, moldings, and doors. Similar to shown: Wagner HVLP sprayer; about $500; amazon.com

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. Lacquers, shellacs, stains, and water sealer: .009 to .013 Enamels: .013 to .015 Oil-based coatings and interior latex paints: .013 to .017 Exterior latex paints: .015 to .019

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.

Fan Settings

Some guns 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.

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.

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.

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.

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.