Selecting the Correct Airless Spray Pump
Choosing the right airless spray pump comes down to one thing above all else: knowing your paint. Get that right,
What Is Airless Spray? How Airless Paint Spraying Works
Airless spray is one of the most widely used ways to apply paint and protective coatings – yet it’s still often confused with conventional spray painting. If you’re new to it, or weighing it up against other methods, this guide covers what airless spray is, how it works, how it compares to conventional and HVLP spraying, and where it does (and doesn’t) make sense.
What is airless spray?
Airless spray is a way of applying paint by pressurising the paint itself, so it atomises without any help from compressed air. A pump pushes paint through a high-pressure hose to the spray gun, where it’s forced through a tiny opening in the spray tip and breaks up into a fine, even fan of droplets.
That’s the key difference from conventional spray painting, where compressed air is mixed with the paint at the gun’s air cap to break it up.
How airless spray works
As paint leaves the spray tip, it starts out as a thin, solid sheet of liquid travelling at very high speed. Resistance from the surrounding air then breaks that sheet into tiny droplets – a process called atomisation. It’s the same effect you get when you put your thumb over the end of a garden hose: narrow the opening and the water speeds up and sprays.
Different paints atomise at different pressures – anywhere from about 80 to 500 bar, depending on the coating – so always check your paint’s data sheet. Your pump needs to deliver that pressure at the gun, not just at the pump, because some pressure is always lost between the pump and the gun – more so with long hoses, thick paint or large tips. Our guide to selecting the correct airless spray pump explains how much headroom you need.
A few things affect how well your paint atomises:
- Viscosity – thicker paint needs more pressure to break up.
- Temperature – cold paint is thicker and harder to atomise.
- Tip size – the tip has to suit both the paint and what your pump can deliver.
When the pressure is too low, you’ll see “tails” – heavier bands of paint along the edges of the spray pattern – instead of a clean, even fan.
The four parts of an airless spray system
Every airless setup is built from the same four components, each with a clear job:
- The pump creates the pressure. There are three types: pneumatic (air-driven, needs a compressor), electric (runs off a standard 220V plug point) and hydraulic (self-contained, with petrol, diesel or electric drive). Which one you need depends mostly on your paint – see Selecting the Correct Airless Spray Pump.
- The high-pressure hose carries paint from the pump to the gun. The longer the hose, the more pressure is lost along the way.
- The spray gun is the on/off valve. Squeeze the trigger and paint flows; let go and it stops instantly. Browse our airless spray guns.
- The spray tip controls how much paint comes out and how wide the fan is. This is one of airless spray’s big advantages: to change your spray pattern, you simply swap the tip – no gun adjustments needed. Our guide on how to choose the right airless spray tip size explains the numbering.
Filters – at the pump and, on many guns, in the handle – catch debris before it can block the tip, so keep them clean.
Airless vs conventional vs HVLP spray
All three are spray methods, but they atomise paint differently – and that shapes what each one does best.
Airless | Conventional (air) spray | HVLP | |
|---|---|---|---|
How paint is atomised | High fluid pressure through a small tip | Compressed air at the gun’s air cap | Compressed air at low pressure – a lower-pressure type of air spray |
Speed of coverage | Fastest | Moderate | Slowest |
Coat thickness per pass | Heavy – builds film quickly | Light | Light |
Transfer efficiency | Up to around 70% | Around 40% | Higher than standard conventional |
Thick, high-solids coatings | Handles them, often without thinning | Often need thinning | Often need thinning |
Finish and control | Smooth, even, professional | Fine control over pattern and finish | Finest control, least overspray of the air methods |
Equipment and running cost | Higher – more high-wear parts | Lower upfront and day to day | Similar to conventional |
Best for | Large areas and high-build coatings: structural steel, walls, ceilings, roofs, floors | Detail and decorative work, metal fabrication, and coatings such as inorganic zinc primers | Panel beating, woodworking, detail and touch-up work |
If you need fine control over the finish, or you’re spraying coatings such as inorganic zinc primers, have a look at our conventional spray painting equipment. For large areas and thick, high-build coatings, airless is usually the faster choice.
The pros and cons of airless spray
Where airless spray shines
- Speed. On big, open surfaces, airless lays down paint many times faster than a brush or roller, so projects finish sooner and labour costs drop.
- Less waste. Airless can transfer up to around 70% of the paint onto the surface, compared with around 40% for a standard conventional gun – so far less is lost to overspray.
- Higher film build. A thicker, even coat per pass means you reach your required dry film thickness (DFT) in fewer coats.
- Handles heavy coatings. High pressure atomises thick, high-solids coatings, often without costly solvent thinning.
- Simple pattern changes. Swap the tip rather than adjusting the gun.
- Even coverage on rough surfaces. Airless lays an even coat on blasted steel, masonry and other irregular surfaces.
- Portable. Equipment moves easily between sites, and electric and hydraulic units need no compressor.
Ready to see the equipment?
Explore our full range of pneumatic, electric and hydraulic airless paint sprayers, plus the guns, tips and accessories to complete your setup – all stocked and supported locally.
Things to consider before you switch
- Cleaning time. The pump, hose and gun need flushing after every job and before changing coatings.
- Wear parts. Tips, filters and pump seals wear and need replacing – budget for them. A worn tip quietly uses more paint, so watch for the signs covered in our tip guide.
- Not for the very finest finishes. Airless gives a smooth, professional result, but panel beating, woodworking and other detail work still call for conventional or HVLP spray.
- Masking still matters. Low overspray isn’t zero overspray – mask carefully, and watch the wind outdoors.
- Training and safety. High pressures need trained operators (more on that below).
Where airless spray is used
Airless spray covers a huge range of work, which is why there are three types of pump:
- Industrial and protective coatings – structural steel, bridges, tanks, ships and offshore structures
- Commercial and residential painting – walls, ceilings, roofs and waterproofing
- Large site and infrastructure work – bitumen, mastics, block fillers and high-build roof coatings
Each application leans towards a different pump. Our range of airless paint sprayers includes a quick reference showing which sprayer suits which job.
A quick word on safety
Airless equipment works at pressures high enough to inject paint through skin, even through gloves – a high-pressure injection injury. It can look minor at first but always needs urgent medical attention. The basics are simple: lock the trigger between passes, keep hands and body clear of the tip, release the pressure before cleaning or changing a tip, and wear the correct spray painting PPE. Storm Machinery offers basic OEM training if your team needs it.
Your next steps
- Choose your pump. Start with your paint’s data sheet, then read Selecting the Correct Airless Spray Pump.
- Size your tip. Match the orifice and fan width to your coating with How to Choose the Right Airless Spray Tip Size.
- Browse the range. Pumps, guns, tips and accessories are all in our airless spray painting equipment range.
- Ask us. Not sure where to start? Our sales engineers will match the right equipment to your paint and project – contact us or call 011 894 2005 (JHB), 031 700 8332 (KZN) or 021 510 6385 (WC).
FAQS
Why is it called "airless" spray?
Because no compressed air touches the paint at the gun. A pneumatic pump uses compressed air to drive its motor, but the paint itself is atomised purely by pressure.
What pressure does airless spray need?
It depends on the coating: different paints atomise anywhere from about 80 to 500 bar, so check your paint’s technical data sheet. Your pump also needs headroom for the pressure lost through the hose – our pump guide explains how much you need.
Do I need to thin paint for airless spraying?
Usually not – many coatings spray as supplied. Always follow your paint’s technical data sheet, which states whether thinning is allowed and by how much.
Can I use an airless sprayer indoors?
Yes, with good ventilation, careful masking and the right PPE. Electric units are the usual choice indoors, as there’s no engine exhaust and no compressor needed.
Is airless spraying better than using a roller?
For large areas, usually – it’s faster and gives a more even film thickness. For small rooms or touch-ups, the masking and clean-up time can make a roller quicker overall.
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