Airless & AirCoat FAQ – all your questions about spraying - Airless Discounter

The Airless Discounter Answer Center

Airless & AirCoat: 40+ questions, just as many clear answers

Here are the questions painters, drywallers, facade specialists and applicators ask us most often — on the phone, by email, and in our Facebook group. Each answer fits in a few lines, with no unnecessary jargon, and links to the detailed article if you want to dig deeper.

41 questions
9 topics
Answers validated by our workshop

Direct access by topic

1. The basics
2. Choosing your machine
3. Tips & hoses
4. Paints & products
5. Technique
6. Troubleshooting
7. Cleaning & maintenance
8. Safety
9. Purchase & support

1. The basics: airless & AirCoat

Understanding what happens between the bucket and the wall.

What exactly is airless spraying?

A pump puts the product under very high pressure and pushes it through a tiny orifice. It’s the sudden passage through this orifice that breaks the paint into fine droplets — with no compressed air mixed into the product, hence the name “airless.” In practice, building paint is sprayed between 80 and 220 bar, with industrial machines capable of exceeding 500 bar. Our complete airless guide covers the principle in detail.

What is AirCoat (air-assisted spraying)?

This is an airless system to which a ring of low-pressure air is added around the spray. This air is not used to atomize the product: it tightens and controls the spray, which gives a remarkably crisp pattern and eliminates almost all the mist. Air pressure never exceeds about 2 bar, and the gun has two inlets: one for air, one for product. Further reading: what is AirCoat?

Airless or AirCoat: which should you choose?

The two aren’t opposites, they complement each other. Field summary:

Criterion	Airless	AirCoat
Products	From varnish to thick fillers	Low viscosity: lacquers, varnishes, wood stains
Mist	Manageable with the right settings	Almost none
Finish	Very good	Superior, especially on profiles
Adjustments	Tip + pressure	Tip + product pressure + air flow
Best suited for	Walls, ceilings, facades, large surfaces	Woodwork, doors, furniture, metal

The full comparison is here: which spraying method to choose, airless or AirCoat?

And what about HEA / low-pressure technology?

HEA stands for High Efficiency Airless. The principle: a tip geometry that allows proper atomization at noticeably lower pressure. The result: up to 55% less mist according to the manufacturer, a less stressed pump, and seals that last longer. At Graco, the equivalent is called the RAC X LP range. See the Wagner HEA ProTip tips.

Can an airless pump be converted to AirCoat?

On some pneumatic machines, yes: you need an AirCoat gun, an air hose, a regulator and a compressed air source. On a standard electric station like the ST MAX or Ultra Max, conversion doesn’t make economic sense. Two useful reads: can an airless pump be converted to AirCoat? and the list of components for the Wagner SF 23.

2. Choosing your machine

The right machine is the one that matches your annual liters, not your wishes.

Which machine for which job volume?

The criterion isn’t the surface area of a single job but the annual volume sprayed. As a rule of thumb: occasional use and touch-ups → compact or cordless machine; regularly working painter on homes → entry-level professional piston station; permanent job sites, large surfaces, several workers → high-output station. An undersized machine wears out much faster than a powerful machine used at 60%.

Electric, gas-powered, or pneumatic?

Electric: the standard indoors — quiet, no exhaust fumes, ready in a minute. Gas-powered: for outdoor job sites with no power (facades, marking, engineering structures). Pneumatic: workshop and industry, when a compressed air network already exists and a smooth, pulsation-free operation is needed, including in hazardous atmospheres. See also the quietest airless devices on the market.

Piston or diaphragm: what’s the real difference?

A piston pump draws directly from the bucket, handles loaded products, and reaches high pressure: this is the professional setup. A diaphragm pump is generally more compact and more affordable, but doesn’t handle thick or abrasive products well. If you ever plan to spray a filler, go straight for a piston pump.

What budget should you plan for an entry-level professional station?

The gap is wide between a consumer machine and a station designed for daily use, and prices change regularly. We devoted a full article to the topic, with up-to-date ranges and what justifies the price difference: what is the average price of an entry-level Pro airless device? Also remember to budget for consumables: tips, filters, hose and preservation fluid.

Do you need a generator? What power supply should you plan for?

Most electric building-paint stations run on a standard 230 V outlet. Two precautions: an extension cord with sufficient gauge and as short as possible (a thin, long extension cord causes voltage drop and triggers shutdowns mid-job), and a correctly sized generator, accounting for the startup peak rather than the rated power. This is a common cause of shutdowns: see why does my airless device shut off while in use?

3. Tips, filters & hoses

The cheapest part of the setup determines the quality of the finish.

How do you read the three digits on a tip (517, 621…)?

The first digit × 10 = the spray angle. A 5 corresponds to 50°, i.e. about 25 cm of spray width at 30 cm from the surface. The last two digits = the orifice diameter in thousandths of an inch: 17 means 0.017″. So a 517 = 50° spray, 0.017″ orifice. The airless tip size chart covers all the correspondences.

What tip size for which product?

Starting guidelines, to be fine-tuned according to the product’s technical data sheet:

Lacquers, varnishes, fine finishes — 0.007″ to 0.013″
Interior wall paints — 0.015″ to 0.021″
Facades, waterproofing products — 0.021″ to 0.031″
Fillers, products with high solid content — 0.027″ to 0.053″
Bitumens, thick products — 0.031″ to 0.071″

A tip that’s too large for your pump’s flow rate causes pressure drops and an uneven finish. Full details: where to buy suitable tips for your device?

How do you know a tip is worn?

Three signals: the spray narrows in width, thick streaks appear on the edges (the “comet tail” effect), and your product consumption rises for the same surface area. The orifice gradually becomes oval-shaped — the spray only splits at the final stage, well after the tip has already been costing you money. See replacing the tip in time.

Are Wagner and Graco tips compatible with each other?

Often yes, as long as the thread matches: 7/8″ (called G) or 11/16″ (called F). It’s not the pump brand that dictates this, but the tip guard screwed onto the end of the gun. Before ordering, note down the gun‘s reference and the thread. Details: which tip systems are compatible between Wagner and Graco?

What hose length can be used?

Every meter of hose causes some pressure loss, and thick products amplify this loss. Beyond a certain length, you need to either increase the hose’s inner diameter or use a more powerful pump — not simply turn the pressure up to maximum. Practical values by machine type are here: what’s the maximum airless hose length?

The pro habit: always keep in the vehicle two tips of your common size, a fine tip, a wide tip, a pack of seals and a spare tip guard. A few dozen euros can save a whole day of lost work.

4. Paints & products

What the machine accepts — and what it refuses.

Can all paints go through an airless sprayer?

The vast majority: acrylics, vinyls, matte, satin, velvet finishes, primers, lacquers, wood stains, varnishes, waterproofing products. The real limit isn’t the type of paint but the viscosity/pump power pairing. A heavily loaded product requires a piston pump and a large-orifice tip. Always check the paint manufacturer’s technical data sheet, which usually states the recommended tip size and pressure.

Should paint be thinned?

With a professional station, usually not: that’s precisely the advantage of high pressure. On more modest machines or with thick products, thinning by around 5 to 10% makes application easier — never beyond what the manufacturer allows, or you risk losing coverage and causing runs. To measure it objectively: knowing your paint’s viscosity.

Can oil-based paint be sprayed?

Yes, with two conditions: solvent-compatible equipment (seals, hose, filters) and cleaning with the appropriate solvent immediately after use. Ventilation and PPE also become more critical than with water-based products. Our dedicated article: can oil-based paint be used with an airless device?

Can filler or render be sprayed with an airless device?

Yes, but not with just any machine. You need a powerful piston pump, a large-orifice tip, an appropriately sized hose — or, for really heavily loaded products, a dedicated auger pump. Resources: everything about render/plaster spraying machines.

Should paint be filtered before spraying?

Yes, as soon as there’s any doubt: an opened can, a skin on the surface, the bottom of a bucket, a product stored for a long time. A single particle is enough to clog a 0.015″ tip mid-pass. The suction strainer, pump filter, and gun filter form three successive barriers — don’t remove any of the three “to gain flow rate.”

5. Spraying technique

Technique matters just as much as equipment.

At what distance and speed should you spray?

About 30 cm from the surface, gun perpendicular to the wall, at a constant speed. The classic mistake is rotating the wrist at the end of a pass: the spray moves away at the ends, the coat thins out and fading appears. The arm moves, the wrist stays fixed.

How much overlap between two passes?

About 50%: each pass covers half of the previous one. An airless spray deposits more product in the center than at the edges; overlapping by half compensates for this difference and gives an even thickness. Pull the trigger before reaching the surface and release it after leaving it.

How do you correctly adjust the pressure?

Start low and increase gradually: turn it up until the spray is just even, with no streaks on the edges, then stop there. Any additional pressure only produces more mist, wears out the tip faster and stresses the lower pump. If the spray remains uneven at maximum, the problem lies with the tip, a filter, or the viscosity — not the pressure.

How can you limit spray mist?

Four levers, in order of effectiveness: work at the lowest pressure that atomizes correctly, use a low-pressure tip (HEA ProTip or RAC X LP), keep the 30 cm distance, and close off any drafts. See also how to protect surrounding surfaces.

How much time do you really save compared to a roller?

In terms of pure application time, the difference is dramatic. But the real gain is measured over the whole job: the time shifted to masking and cleaning reduces the advantage. Airless becomes clearly worthwhile once the continuous surface area is large or the substrates are irregular (render, textured, cladding) — that is, exactly where a roller is slowest.

6. Troubleshooting: the six most common issues

What we hear most often on the phone.

The pump won’t prime

In order: check that the valve is set to prime position, that the suction tube is actually submerged in the product, and that the suction strainer isn’t clogged. If everything checks out, the most common cause is a check-valve ball stuck by dried residue — a sign of insufficient cleaning on the previous job. A product that’s too thick or too cold also makes priming harder.

The spray leaves “comet tails” or streaks

A typical symptom of a worn tip or insufficient pressure for the product’s viscosity. Test in this order: replace the tip with a new one of the same size; if the spray is clean, the tip was the cause. If not, check the filters and raise the pressure step by step. Details: why isn’t my airless device spraying evenly?

The machine sprays in jerks

The spray cuts out and resumes: the pump can no longer maintain pressure. Common causes: an air leak at the intake, a clogged filter, a worn check valve or tired lower pump seals. The full diagnosis is here: why does my airless device only spray in jerks?

The machine won’t start at all

Before concluding it’s a motor fault, rule out the trivial causes: power supply, undersized extension cord, pressure knob set to minimum, safety engaged, product hardened in the pump after storage. We’ve listed the eleven possible causes, from simplest to most technical: 11 causes and solutions.

The machine shuts off mid-use

Nine times out of ten, the cause is electrical: a voltage drop due to an extension cord that’s too long or too thin, an undersized generator, or a thermal cutout tripping after overheating. See why does my airless device shut off while in use?

My pressure gauge is only half-filled with fluid: is this a problem?

No, in most cases. The damping fluid in glycerin-filled pressure gauges contracts with temperature, and it’s normal for a small bubble to appear. What should raise concern is a stuck needle or a reading inconsistent with the machine’s behavior. The detailed answer: partially filled pressure gauge.

7. Cleaning, maintenance & winter storage

Almost all breakdowns happen right here.

How often should you clean your machine?

After every use, without exception, and immediately — not the next morning. A full rinse takes about fifteen minutes; a seized lower pump means a workshop repair. The detailed schedule by product type: how often should I clean my airless device?

Can paint be left in the machine from one day to the next?

For a short break, with water-based product and if the suction remains submerged, it’s possible — provided you depressurize and protect the tip from drying out. But once it’s a matter of several days, a solvent-based product, or high temperatures, a full rinse remains the only sensible option. The risk isn’t wasted paint, it’s a jammed check valve.

How do you winterize a paint sprayer?

Full cleaning, then filling the circuit with a dedicated preservation fluid (such as Pump Armor or equivalent), which protects the seals from drying out and the circuit from freezing. Warning: automotive engine coolant/antifreeze is not an airless storage fluid, even if the color is identical — the chemistry is different. See coolant fluid ≠ storage fluid and our tips for the winter break.

How do you maintain the lower pump?

This is the machine’s main wear part. Three steps: careful rinsing after each use, a few drops of throat seal oil in the designated cup before each working day, and replacing seals as soon as seepage appears.

How do you unclog a tip without damaging it?

With a reversible tip: depressurize, turn the tip half a turn, briefly pull the trigger to blow the clog out backward, then put it back in position. Never use a needle, wire, or metal point: scratched carbide is permanently ruined. See unclogging an airless tip and how to clean your tips.

8. Safety

Two hundred bar doesn’t forgive improvisation.

What protective equipment is needed?

At a minimum: a respiratory mask suited to the product (filters differ between water-based and solvent-based products), safety goggles, gloves, and covering clothing. The tip guard must always stay in place. The regulatory framework is detailed in what safety standards must be followed?

What should you do in case of product injection under the skin?

This is a surgical emergency, regardless of how the wound looks. A jet at 200 bar can pass through skin and inject product into the tissue, often leaving only a tiny mark that isn’t very painful in the first few minutes. Go immediately to the emergency room, specify that it’s a high-pressure injection and not a simple cut, and bring the product’s safety data sheet. Never treat this injury yourself, and don’t wait to “see how it goes.”

Can you spray in an unventilated room?

This is strongly discouraged, and frankly to be avoided with solvent-based products: fume buildup, respiratory risk, and depending on the product, risk of a flammable atmosphere. Provide mechanical or natural ventilation, appropriate respiratory protection, and breaks. Our dedicated article: can an airless device be used in unventilated rooms?

Should you depressurize before every intervention?

Systematically, before any disassembly: tip, filter, hose, tip guard. The procedure is always the same — turn off the machine, set the valve to drain position, lock the trigger. The circuit stays under pressure even with the machine off: this is exactly where injection accidents happen.

9. Purchase, delivery & service

Our terms for France and Benelux.

Do you deliver to Irland, Sweden, France, Belgium, Danemark and Luxembourg?

Yes. We ship from Berlin throughout Irland, France, Belgium, as well as the rest of continental Europe. Rates and delivery times are shown directly in the store when ordering. More information: Shipping Costs & deliveries.

How can you be sure of ordering the right spare part?

Have the exact model of your machine and its serial number ready. Our blog regularly publishes exploded views with part references by model, and our team identifies the reference from this information. For tips, it’s the gun‘s reference and the thread that matter: see where to buy suitable tips.

Where can I get my station repaired?

We maintain an up-to-date directory of partner repair services across France as well as our main repair center in Berlin, for all Germany. Find our French list here: airless repairs page.

Do you offer spraying training?

Yes. Our Berlin training center regularly organizes one-day sessions dedicated to spray technique: settings, technique, tip selection, maintenance. Program and dates on the training for airless painters page. The 1 day training is available in German, French and English.

The video demonstration

Watch before you start

Some techniques are easier to understand in pictures than in paragraphs: spray distance, pass overlap, pressure adjustment, cleaning the lower pump.

This FAQ also exists in video form

Our Airless Tips series answers more than 20 painters’ questions, one by one, with demonstrations to back them up: settings, tips, cleaning, troubleshooting.

Watch all 23 answers on video

Don’t see your question here?

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