Airless paint sprayers: Pros and Cons
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.
Figure A: Airless sprayer parts
Airless Sprayers: 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 oil-based
products like lacquer, oil stain or oil
paint, so be sure to ask.
Sprayer set-up: Prime the pump
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.
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
Sprayer set-up: Fill the hose and 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 and 4A).
Pressure relief steps
- Turn off the power switch.
- Turn the spray/prime valve to prime.
- Aim the gun against the side of the
waste pail and pull the trigger to release
- Engage the trigger lock.
Choose the Best Tip for the Job
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
Sprayer set-up: 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
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
- Overlap your strokes about 30 to 50
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Most spray problems are a result of
clogged filters, a clogged tip (Photo 8), 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
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.
Airless Sprayer Safety
Read and follow the safety precautions
included in your
sprayer manual. If you rent a
sprayer, ask for a list of precautions.
Here are the most important
- Keep the trigger locked and
follow the pressure relief procedure
when you stop spraying,
before cleaning, and
before servicing the sprayer or
installing tips. Never put your
hand in front of the sprayer
tip unless the unit is off and
depressurized. The high-pressure
spray can inject paint
under your skin, causing a
serious poisoning hazard. If
you do puncture your skin
with the spray, get to a doctor
- Wear safety glasses and an
approved respirator when
- Work in a well-ventilated area.
Caution: When you’re spraying
flammable oil-based products,
follow all grounding precautions
to prevent sparks. Read
your manual or ask the rental
store for instructions on grounding the gun and metal pail.