How to Clean an Airless Paint Sprayer: 8 Steps + Storage

Airless sprayers rarely die of wear. They die of neglect in the two hours after the job finishes, when the paint is still wet enough to seem harmless and tired enough to skip. A thin film left inside a pump or a filter costs nothing to remove on the day of the job, and costs a pressure problem, a stripped manifold or a new pump three weeks later. The machine will start on that second job, which is what makes the omission so easy to repeat.

What follows is the cleaning routine we run on our own machines, in the order that matters: relieve pressure first, flush with the right fluid, pull all three filters rather than the one you can see, then dry the pump before it goes into storage. In our experience, the failures people bring to us cluster in three places: a filter that was never removed, oil-based paint flushed with water, and water left sitting in the pump over winter. All three are avoidable in under fifteen minutes.

Step Zero: Relieve the Pressure

Every airless sprayer manual opens with the same instruction, and it is not legal boilerplate. An airless pump holds thousands of PSI in the hose after the motor stops, and a pinhole in that line will inject fluid into flesh rather than spray it at it. That kind of injury is a surgical problem, not a first-aid one. So the routine starts with pressure relief, before the gun comes apart and before anything is unscrewed.

The sequence is the same on almost every airless machine. Lock the gun trigger, switch the pump off, wind the pressure control down to its lowest setting, then point the gun into a waste pail and release the trigger lock and the trigger to dump the residual pressure. Confirm on the gauge that it has dropped to zero, then switch off at the outlet. Only after the gauge reads zero should you loosen a fitting. Consequently, the pressure relief step is also the best moment to check the gauge works, because a stuck gauge is a fault you want to find while the machine is idle rather than mid-job.

What You Need in Front of You

Gather the supplies before you start, because walking away mid-flush is how paint dries inside a line. You need a bucket of warm water for latex, or a container of mineral spirits for oil-based coatings, plus a second empty pail for the waste. Add a soft brush for the filters and tip, the hex key that came with the machine for the filter housing, and the cleaning brush supplied with the unit. Wear gloves and eye protection; you are handling solvent and pressurised fluid at the same time.

The waste itself needs a plan. Leftover paint and solvent count as household hazardous waste, and pouring them down a drain or onto the ground is illegal in most places, so check your local disposal route before the day you need it (epa.gov, 2025). Keep the two waste streams separate as well; mixed solvent and water is harder to dispose of than either on its own. If you are spraying anything flammable, ventilation and ignition control matter more than the cleaning itself, and the regulatory requirements for spray finishing operations are set out in 29 CFR 1910.107 (2025).

Steps 1 to 3: Empty, Flush, Purge

Lift the suction set out of the paint and let it drain back into the bucket, then wipe the outside of the intake and drain tube so you are not carrying a coat of paint into the flush. Move the suction set into the flushing fluid, set the prime valve to spray, turn the pump on and trigger the gun into the waste pail. What comes out first is paint, then paint thinned with fluid, then a milky mix, and finally clear fluid. Keep going until it is clear and stays clear through a full trigger hold.

That last point is where most people stop too early. The test is not how many seconds you ran the pump or how much fluid you used; it is what comes out of the gun. If the stream is still milky, there is still pigment in the line, and that pigment will settle in the pump or the filter and harden. Change the flushing fluid when it turns opaque rather than pushing the same dirty bucket through the circuit again, and remember to flush the return line and the drain tube as well, because those hold paint just as the hose does. Notably, warm water works better than cold for latex, because it breaks the paint down faster and carries it out of the line instead of smearing it along the wall of the tube.

Steps 4 to 6: The Three Filters Most People Skip

An airless sprayer has three separate filters, and cleaning one of them is the same as cleaning none. The intake filter sits in the suction set and stops debris from the paint bucket reaching the pump. The high-pressure filter sits in the manifold or the filter housing and protects the pump and hose from anything fine enough to pass the intake. The gun filter sits in the handle, and it is the one almost everyone forgets because the gun looks like a solid casting.

For example, a spray pattern that starts as a clean fan and then breaks into streaks down the middle is usually the gun filter, not a worn tip. Replacing the tip then makes no difference and the filter stays in place, which is why the same fault reappears on the next job. Clean all three every time the machine is put away, and note which ones were replaced so you are not guessing later. If a filter will not come clean after soaking, replace it; a filter costs a fraction of the pump it protects.

Steps 7 and 8: Dry It, Then Store It

Water is the enemy of a stored airless pump, for two separate reasons. Left in the pump body it promotes corrosion on the internal parts, and in a cold garage it freezes and expands, which can crack a pump housing or distort a valve seat. Oil-based residue left behind does not freeze, but it dries into a varnish that binds the piston and the valves. So the last two steps are about leaving nothing in the machine at all: drain the flush fluid out, then fill the pump with a purpose-made pump protector before it goes on the shelf.

Short stops are a separate case. If you are spraying again tomorrow morning, the manufacturer's short-term storage procedure is enough, and that usually means leaving the pump wet with the matching fluid rather than stripping and drying the whole machine. Anything longer, and especially anything that crosses a winter, deserves the full treatment. Pump protector fluid is deliberately formulated to do two jobs at once, coating the internal surfaces and resisting freezing, which is why substituting engine oil or plain antifreeze is a false economy: neither is designed to stay in suspension inside a pump, and both can leave deposits that do exactly what you were trying to avoid.

Latex vs Oil-Based: One Decision, Two Paths

The only decision that changes the routine is what to flush with, and the rule is simple: the flushing fluid is the paint's thinner. Latex and other water-based coatings flush with warm water. Oil-based enamels, varnishes, stains and most solvent-borne products flush with mineral spirits. Nothing else in the process changes, which is convenient, because the two paths differ only in the bucket you carry over to the machine.

Two practical refinements are worth knowing. First, water-based paint that has already started to skin over flushes far more easily if you add a small amount of warm water and let it sit for a few minutes before running the pump, because it softens the film in the pickup and the hose. Second, when you switch from one type of coating to the other, flush twice: once with the old coating's solvent to remove the paint, then once with the new coating's thinner so the line is chemically clean. Skipping the second pass leaves a trace of the first fluid in the system, which can curdle the new paint or leave fisheyes in the finish.

Our 3300 PSI Machine, Start to Finish

Our team tested the MAXXT 3300 PSI airless sprayer, a stand-mounted unit with a 0.82 horsepower pump core delivering 0.32 gallons per minute, three selectable pressure stages at 500, 1500 and 2900 PSI, and a 7.5 metre pressure hose. We measured a full flush of the hose and gun at roughly two minutes at the middle pressure setting, with a further few minutes if the gun filter and the manifold screen both come out for cleaning. The 7.5 metre hose holds a real volume of paint, which is worth remembering: the longer the hose, the longer the flush, and the more paint you recover into the waste pail rather than into the finish.

The unit ships with the parts you need for the job rather than as extras, which matters more than it sounds on cleaning day. In the box are a pressure gauge, a feed pipe, the 7.5 metre pressure hose, a spray gun and nozzle, a filter, a cleaning brush, and the hex key for the filter housing. That hex key is the difference between pulling the high-pressure screen in thirty seconds and improvising with pliers and rounding the cap. For lighter work, the 1300 W stand sprayer runs the same three-stage pressure logic up to 3200 PSI with a 304 stainless steel pump core, and takes the same cleaning routine.

Troubleshooting: Five Symptoms and What They Mean

Most cleaning-related faults announce themselves in a specific way, and matching the symptom to the cause saves stripping parts that were never the problem. The following five cover nearly everything we are asked about.

• Pressure will not build. Usually a blocked intake filter or a leaking suction seal, not a failed pump. Check the O-rings and the intake screen before looking at the pump.
• The spray fan breaks up in the middle. A dirty gun filter nine times out of ten. Clean or replace it before buying a new tip.
• The pump pulses or knocks. Dried paint on a valve seat. Flush the machine thoroughly and store it with pump protector, and the knock usually clears.
• The flush water never runs clear. The fluid is saturated. Swap the bucket and flush again rather than running the same dirty fluid through the circuit.
• Nothing comes out the next morning. The machine was put away wet with paint, and the line has skinned over. Soak the suction set in warm water, then flush and store it properly.

Frequently Asked Questions

Final Thoughts

Cleaning an airless sprayer is fifteen minutes of unglamorous work that decides whether the machine lasts three jobs or thirty. Relieve the pressure before anything comes apart, flush with the thinner that matches the paint, pull all three filters rather than the visible one, and leave the pump full of protector rather than water. Do that and the next job starts with a clean prime instead of a diagnosis. You can browse the airless paint sprayer range to compare pressure ratings and hose lengths, read our guide to spraying a wall with a spray gun if you are still working out technique, or look at cleaning up paint and drywall dust for the rest of the job site. For questions about which model suits your coatings, you can contact our team, or read more about us and how we test tools before we recommend them.

References

1. Occupational Safety and Health Administration. "Spray Finishing Using Flammable and Combustible Materials, 29 CFR 1910.107." osha.gov (2025).
2. Environmental Protection Agency. "Household Hazardous Waste." epa.gov (2025).
3. Graco. "How to Clean Up a Paint Sprayer." graco.com (2025).
4. Graco. "Magnum TrueAirless Electric Airless Sprayer Operation Manual." graco.com (2024).
5. Popular Mechanics. "How to Clean a Paint Sprayer: An Expert's Step-by-Step Guide." popularmechanics.com (2025).