When hearing the words spray paint, the first image that pops up in people’s mind is probably an image of Banksy (how do you picture an anonymous artist though?) spray painting in the crumbling remains of war-torn Gaza or perhaps a dedicated hobbyist applying finishing touches on their model kits from one of those famous Japanese giant mecha series with an airbrush.
While it’s true that popular depictions of spray painting are usually restricted to the finer things in life, spray painting sees a lot of usage in industrial and residential use, with the numerous variations of spray guns being used to paint cars, properties and furniture.
As these works are of a larger scale, the equipment used is comparatively bigger than the average spray cans and airbrushes with some, like airless sprayers, coming with an actual pump for high-volume painting.
Generally, when it comes to industrial work, spray painting is done with two primary sprayer, the high-volume low-pressure (HVLP) paint sprayer and the airless paint sprayer but this is not strictly an either/or situation. The differing nature of these two tools means that even if there is some overlap between the two, they mostly have their own several niches to fill in the world, just like how painting with an airbrush and an aerosol spray can will result in two different finishes. The differences between how the two operates and are used are quite fundamental but the general gist is as follows.
High-volume low-pressure for detailed work
The HVLP part refers to the way air, usually pumped from an air compressor, is used to atomize the paint. This is distinctly different from an airless paint sprayer which obviously doesn’t use an air compressor.
The HVLP is special in that unlike conventional spray gun, it gobbles up large amounts of air, measured in cubic feet per minute or CFM, requiring at least 20 CFM of air compared to conventional spray guns that tops out at around 10 CFM.
For practical use, the HVLP sprayer is the gavel to the airless sprayer’s sledgehammer and has a transfer rate of more than 80%, producing considerably less waste than an airless sprayer. While nowhere near as subtle as a dedicated airbrush, the HVLP is efficient enough to be used in situations that require a certain degree of precision, like when painting furniture or any surface that isn’t flat.
This efficiency is also enhanced by the fact that most HVLP sprayer allows you to adjust the volume of the paint material and air you are spraying with, allowing for a degree of customization impossible with airless sprayers and suited when working with finer materials.
Regarding the quality of the result, an HVLP sprayer is capable of providing a better finish, as the atomized output is smaller when compared to an airless sprayer. It’s not going to matter with latex-painted wall but for finer materials like enamel or when you’re going for a certain finish when painting car, an HVLP sprayer is simply indispensable.
The fact that an HVLP sprayer results in less overspray when compared to conventional and airless sprayer also means that not as much cleanup and preparation is required when working with an HVLP.
Still, an HVLP sprayer does have its own limitation, the primary of which deals with its lack of capability when it comes to high viscosity coatings. As an HVLP sprayer uses a low-pressure system, high viscosity coatings may require thinning first before spraying and even then, they might not atomize as well as thin to medium coatings.
The second limitation revolves around the simple fact that an HVLP sprayer requires the use of an air compressor and when combined with the HVLP sprayer itself could carry quite a hefty price tag.
Airless for high production work
Airless sprayers are called such because they don’t use air to atomize the paint at all. They function as the opposite of an HVLP sprayer as it works by pressurizing the paint material using a piston and spraying them out of a small opening, much smaller than what you would see in an HVLP sprayer.
This combination of pressure and squeeze atomizes the paint into particles. As the output coming out of an airless sprayer is pressurized, reaching as high as 2000 psi in some cases compared to 10 psi typical of an HVLP sprayer, proper care need to be considered when handling an airless sprayer as it is capable of causing severe injuries.
Compared to the efficient HVLP sprayer, an airless sprayer operates merely at 50% efficiency, generating more waste but operating at a much faster rate, emptying paint at a rate up to 7 liters per minute compared to HVLP’s dismal rate of 600 milliliters per minute. This is the primary reason why an airless sprayer is mainly used for high production work; it is extremely fast with the caveat of severe overspray, making it restricted to large and flat surfaces. Thanks to its high pressure, airless sprayer works extremely well even with thick paints and higher viscosity coatings without the need of thinning, the complete opposite of an HLVP sprayer.
As for the quality of the finish, well, there really isn’t much to speak of. Like a shotgun, with an airless sprayer all you have to do is point and shoot. It is possible to change the tip to accommodate higher quality finishes but it still won’t match the result you’d get with an HVLP sprayer. As they lack built-in granular control of an HLVP sprayer, achieving precision and uniform results with an airless sprayer is rather difficult.
HVLP and airless sprayers is not a binary choice, they complement each other and are suited to different workloads. Choosing one or the other basically revolves around the kind of work you intend on doing. HVLP sprayers are suited for flat and uneven surfaces, anything that requires a certain level of finish and anything requiring expensive paint materials. On the opposite end of the spectrum, airless sprayers are suited to wide and flat surfaces like building exteriors or any work where speed is essential and quality is secondary.