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Airless sprayers are an exciting option for anyone who wants to lay down thin, even coats of liquid on metal, wood, or certain types of plastic. However, they come with a significant drawback: overspray.
In this article, learn about airless sprayers and overspray, including how much overspray you should expect and how much material you will lose to overspray.
- What Is an Airless Sprayer?
- What Is Overspray?
- Anatomy of Airless Sprayers
- How Much Overspray Should I Expect from an Airless Sprayer?
- How Much Material Will I Lose to Overspray?
What Is an Airless Sprayer?
Airless sprayers are machines used to turn a liquid into a spray of atomized particles. Rather than applying the liquid with a brush, rag, or roller, the airless sprayer is used to apply paint, stain, varnish or lacquer to a variety of surfaces.
Liquids must be properly thinned in order to move through the various parts of the airless sprayer and exit the nozzle without clogging. When used appropriately, airless sprayers provide thin, even coverage without brushstrokes.
Don’t be confused with an HVLP sprayer – an airless sprayer is different!
Handheld Airless Sprayer
In a handheld airless sprayer, the motor, pump/fluid container, and pressure control are all mounted on a spray gun.
Handheld airless sprayers are easier to move around with than mounted airless sprayers, which may also be referred to as ‘stationary’.
Mounted Airless Sprayer
Mounted airless sprayers have the mechanical pump mounted on a frame. Often the frame has wheels on it so it can be moved around on a single floor, but must be carried up and down stairs. The motor and pressure control are also mounted on the body of the machine. A hose connects these elements with a spray gun.
Read our reviews of the top HVLP paint sprayer to find the right option for your project.
What Is Overspray?
A major drawback of airless sprayers, whether mounted or handheld, is overspray. Overspray can be defined as any sprayed material that makes it out of the airless sprayer, but does not adhere to your chosen surface.
When liquid is atomized, it becomes very light. Even the high pressure of an airless sprayer is not adequate to direct every particle of the atomized substance to your chosen surface.
Overspray is a problem for two reasons:
- You lose a significant amount of your material to overspray. This increases your material cost and affects the calculations for how much liquid you need to cover a given area.
- You must protect everything in the area that you don’t want sprayed from flecks of paint, stain, lacquer, or varnish. This is true whether you’re working with a handheld or mounted airless sprayer.
Anatomy of Airless Sprayers
All airless sprayers have more or less the same parts, whether they are mounted or airless. Understanding how an airless sprayer works will help you understand where overspray comes from and how much to expect.
The motor drives the pump. It can be powered by direct current electricity, as is the case with mounted airless sprayers. In this case, it needs to be plugged into your nearest outlet.
Handheld airless sprayers are usually battery powered, requiring the user to stop spraying to charge the battery should it run out before the job is complete.
Some airless sprayer models, whether mounted or handheld, are capable of drawing paint or other products directly from the can or bucket.
Others have a container that must be filled (and refilled) as you work. The pump pressurizes the liquid, turning it into a spray, which is released from the nozzle.
Handheld airless sprayers may not have a hose, since the pump is connected directly to the spray gun. A hose may be used if the airless sprayer has the capability to draw up paint directly from a separate container, eliminating the need to refill to the fluid section.
In mounted airless sprayers, the pump is connected to the spray gun by a hose. As the fluid moves through the hose, it can lose pressure depending on the hose’s length. An important metric to understand is how long a hose your particular model of airless sprayer can support.
If you’re renting a mounted sprayer, make sure you ask about the appropriate length of hose in order to get the best results out of the machine.
In many models of airless paint sprayer, you can adjust the amount of pressure created by the pump. For smaller projects, such as finishing trim, a lower pressure setting will produce less overspray.
On larger projects, like spraying onto walls, a higher pressure setting will get the job done faster.
When the machine is powered on and filled or connected to liquid, squeezing the trigger will release the pressurized liquid in a fine spray.
The nozzle is the part of an airless sprayer where the spray exits the machine.
Spray tips are used to shape and control the spray as it exits the nozzle. The most common spray tip is a fan shape. These emit spray in a thin line, and can be oriented horizontally or vertically, depending on the needs of your project.
The size of the spray tip needed is dependent on the material you are spraying.
- Thin liquids work best with smaller spray tips, which also have better control.
- Thicker, viscous liquids will clog tips that are too small, and require larger spray tips for a clean application.
Most airless sprayers come with at least one or two tips. You can purchase individual tips or sets with multiple spray tips to customize the spray from your airless sprayer.
Spray Tip Guard
Spray tip guards are a feature of some spray guns that help collect dried paint and keep it away from the nozzle.
How Much Overspray Should I Expect from an Airless Sprayer?
The amount of overspray you get from an airless sprayer is dependent on a few factors.
- First, the environment in which you are spraying plays a part.
- Then we must consider the pressure settings of the airless sprayer, the length of the hose, and the spray tip you are using.
- Finally, the size of your project plays a role in how much overspray to expect.
Spraying outside on a windy day will result in more overspray than if you apply the same material in a sheltered environment.
Spraying indoors will reduce the amount of overspray that is carried away by wind, although air currents indoors can also contribute to overspray.
Using the lowest possible pressure setting that meets the needs of the job at hand is a good method to reduce overspray. The higher the pressure is set, the more forcefully the spray will exit the nozzle, and the less control you’ll have over where the spray goes.
Size of Project
By default, if you’re trying to spray something that is thinner than the width of your spray pattern, you’re going to have a lot of overspray. Table legs and trim are prime examples of this principle.
When your surface area to be coated is larger than the stream of spray produced by your airless sprayer, there will be much less wasted material.
How Much Material Will I Lose to Overspray?
A good rule of thumb is to expect that 20 to 40% of your material will be lost to overspray. This is true whether you are spraying polyurethane, stain, lacquer, varnish, or paint.
Spraying indoors, with the lowest possible pressure setting, and an appropriately shaped and sized tip can help you limit the amount of material wasted via overspray to around 20%, saving money and time.
Spraying outdoors, using a higher than necessary pressure setting, or an inappropriately sized tip will increase the amount of overspray you experience, and the amount of material you lose.
Overspray is unavoidable when working with airless sprayers. The size of the project, environment of the application area, and the pressure setting of your airless sprayer all contribute to the amount of overspray you should expect. Plan on losing 20 – 40% of your material to overspray when working with an airless sprayer.