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An airless sprayer simplifies painting in two ways: First, if you want to speed up a job that requires several gallons of paint, you can apply it twice as fast as with a roller or brush.And second, if you want a glass-smooth finish on woodwork or doors, the airless sprayer can lay the paint on flawlessly.
An airless sprayer works by pumping paint at a very high pressure, up to 3,000 psi, through a hose and out a tiny hole in the spray gun tip. The tip is designed to break up the paint evenly into a fan-shaped spray pattern of tiny droplets.Using different tips, you can spray thin liquids like stain, lacquer and varnish or thicker liquids like latex house paint. With a little practice, you can use an airless sprayer to apply a perfectly smooth finish on doors, cabinets and woodwork. And since an airless sprayer pumps paint directly from a can or 5-gallon bucket, you can apply a lot of material in a short time. This makes an airless sprayer particularly well suited for large paint jobs, like priming bare drywall in a new house or painting a 300-ft.-long privacy fence.
But before you get too excited about the benefits of spray painting, there are a few drawbacks to consider. First, the fine particles of paint don’t all stick to the surface. A large percentage of the paint ends up in the air, where it can drift and settle onto everything in sight. This means you’ll be wasting 20 to 40 percent of the finish, depending on the application. You’ll also have to take extra time to mask off and cover up everything you want to keep paint free. Outdoor painting is especially risky. Overspray can end up on your shrubs or roof, or drift with the wind onto your neighbor’s car.
The other downside is the extra time it takes to flush the paint from the pump and hose and clean up the spray gun. If you’re using your own sprayer, rather than a rental unit, you’ll also have to clean the filters and install special storage fluid. And if you’re spraying oil-based products, you’ll have to store or recycle a gallon or two of used solvents left over from the cleaning process. But despite these disadvantages, an airless can save you a lot of time on big paint jobs and allow you to get a finish that’s nearly impossible to get with a brush.
Rent or buy?
Airless sprayers start at about $200.
Spending more doesn’t necessarily get you
more features, but it does get you a bigger, better motor and pump, which will deliver
longer life and trouble-free operation.
Owning a sprayer allows you to spray
whenever you want and to ensure that the
sprayer is clean and well maintained.
Renting is a good option if you don’t expect to use the sprayer very often and want to avoid the extra maintenance. You can rent an airless sprayer for about $75 per day.Make sure the hose and pump are clean and that the filters have been cleaned or replaced.Ask for help in choosing the right spray tip for the job. Some rental stores won’t allow you to spray oilbased products like lacquer, oil stain or oil paint, so be sure to ask.
FIGURE A Power painter parts
Click Image to enlarge.
Setting up the sprayer
Whether you rent or buy an airless
sprayer, there are a few key setup points.
All sprayers have a screen at the intake
point. Make sure it’s clean. Most sprayers
also have a removable filter near the pump
and another one in the handle of the gun.
Check both to make sure they’re clean,
and plan to strain your paint through a
mesh filter bag to remove lumps so they
won’t clog the filters.
Prime the pump
Before you can start spraying, you have to
prime the pump. Photos 1 and 2 show
how.You may have to repeat this process if
the paint in the bucket runs out while
you’re spraying.
If paint won’t come out of the prime tube, the problem may be a clogged screen or filter, or a stuck ball-check valve in the pump assembly. If the sprayer you’re using doesn’t have a push-button on the pump to free the stuck ball, try to dislodge it by gently tapping the lowest end of the pump with a hammer. Otherwise follow the suggested troubleshooting procedure in your manual or call the rental store for help.
Click Image to enlarge.
1. Place the smaller prime
tube in a waste pail
and the suction tube in the
bucket of strained paint.
Turn the prime/spray valve
to “prime.” Switch on the
pump. Turn the pressure
valve up until the pump
starts. When the paint
starts flowing from the
prime tube, move it into
the paint bucket.
Fill the hose
and set up the gun
Once the pump is primed, you’re ready to
fill the hose with paint (Photo 3). Then
lock the trigger and relieve the pressure
before installing the tip guard assembly
and inserting the tip (Photo 4).
Pressure relief steps
1. Turn off the power switch.
2. Turn the spray/prime valve to prime.
3. Aim the gun against the side of the waste pail and pull the trigger to release the pressure.
4. Engage the trigger lock.
Click Image to enlarge.
2. Clip the prime tube to
the suction tube. Let
the pump run for about 30
seconds or until no more
air bubbles come out of
the tube.
Click Image to enlarge.
Fill the hose
3. Hold the gun (guard
and spray tip
removed) over the waste
bucket and pull the trigger.
Switch the valve to
the “spray” setting. Let
go of the trigger when
paint is flowing in a
steady stream from the
gun. Lock the trigger and
follow the “Pressure
Relief Steps” (see left).
Click Image to enlarge.
Install the tip
4. Screw the guard assembly loosely onto the gun and align the guard at a 90-degree
angle to your desired spray pattern. Insert the spray tip until the tab is engaged.
Rotate the tip to face the arrow forward. Snug the guard assembly hand-tight.
Choose the right tip |
||
| Spray tips slide into a hole in the
front of the gun. They’re labeled
with a three-digit number like 309
or 517 (these may be the last three
digits of a longer model number).
Doubling the first digit tells you
the spray fan width with the gun
held 12 in. from the surface. A 415
tip, for example, would have an
8-in.-wide fan, while a 515 would
have a 10-in. fan pattern. The next two digits indicate the size of the hole in thousandths of an inch. Choose a smaller diameter hole (.009 to .013) for thin liquids like stain or varnish and a larger hole (.015 or .017) for thicker liquids like latex paint.  A 411 tip would work well for
spraying varnish on woodwork,
while a 517 is a good size for
spraying large
surfaces with
latex paint.
|
||
Adjust the pressure
Too little pressure will result in an
uneven spray pattern. And too much
pressure causes excessive overspray and
premature tip wear. Photo 5 shows how
to dial in just the right amount. If you’re
still getting “tails” or an uneven spray
pattern even at maximum pressure, try
using a tip with a smaller hole. If the
spray pattern is round rather than narrow,
the tip is worn and should be
replaced.
5. Turn on the pump and move
the prime/spray lever to the
“spray” position. 
Spray a strip of
paint across a piece of cardboard to
check the spray pattern. If the spray
pattern has tails, the pressure is set
too low. Turn up the pressure until
the paint is evenly distributed
across the fan pattern (below).
Spraying techniques
Click Image to enlarge.
6. Squeeze the trigger
before you reach the
edge of the door. Move
the sprayer quickly across
the door, keeping it parallel
to the surface. Release
the trigger when the
sprayer is past the opposite
edge of the door.
Click Image to enlarge.
7. Overlap about half of
the previously painted
strip when you make
the next pass with the
sprayer. Keep the gun perpendicular
to the surface.
Photos 6 and 7 show the correct spray techniques. Here are a few key points:
• Plan your spraying sequence before you start. On doors, for example, spray the edges first. Then spray top to bottom. Then spray at right angles side to side.
• Squeeze the trigger while the gun is off to the side, and then move it onto the work (Photo 6).
• Move the gun parallel to the surface, not in an arc.
• Keep the gun perpendicular to the surface, not tilted (Photo 7).
• Move fast to prevent runs. Several thin coats are better than one thick one.
• Overlap your strokes about 30 to 50 percent.
Troubleshooting
Most spray problems are a result of
clogged filters, a clogged tip (below), or
a pump that’s either leaking at the
packing or has stuck ball-check valves.
Careful cleaning and proper maintenance
will prevent most of these
troubles.
Other problems, such as runs and uneven coverage, are caused by using the wrong tip size or by a lack of spraying experience. As with most construction tasks, practice is the key to success.
If paint stops flowing or sputters from
the gun, the tip may be clogged. Twist
the tip 180 degrees. Point the gun at a
scrap of paper and squeeze the trigger
to clear the clog. Rotate the tip 180
degrees to point it forward again and
spray a test strip onto the scrap
|
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