How to Use a Throohills HVLP Spray Gun

The short answer

An HVLP spray gun needs three things set right: thinned, strained paint; the right nozzle; and the right air pressure at the gun. Throohills sells three guns: the Throohills 4001 Siphon Feed HVLP Spray Gun… with a 1000cc cup below the gun, and the Throohills 2008 Gravity Feed HVLP Spray… and Throohills H827 Gravity Feed HVLP Spray…, gravity-feed guns with a 600cc cup on top. The kits include nozzle sets, a regulator with a pressure gauge on most versions, paint strainers and a cleaning kit — everything except the compressor.

Know your gun

Before you spray

• Compressor. HVLP guns use a lot of air at low pressure. Check your compressor's CFM rating against the gun's needs before buying; a small pancake compressor will run constantly and struggle.
• Paint. Thin it to the paint maker's spray viscosity, then pour it through one of the included strainers into the cup. Lumps block the nozzle.
• Nozzle. Fit the size for the job — the picker below — and tighten the air cap by hand.

Step by step

1. Fill the cup. On the gravity guns the cup screws on top; on the 4001 the aluminium cup clips on below. Fill it no more than about three-quarters.
2. Connect the air. Fit the regulator with gauge at the gun's air inlet, where your kit includes it, then connect the compressor hose.
3. Set the pressure. With the trigger pulled, set the gauge to the paint maker's recommendation; most HVLP guns run in the 20–30 psi range at the gun. Too low and the paint spits; too high and it bounces back as overspray.
4. Adjust the pattern. Use the fan knob for the width of the spray and the fluid knob for the amount of paint. The listings note the air cap turns 360° to set a horizontal or vertical fan.
5. Test on scrap. Spray cardboard until the pattern is an even oval with no heavy centre or spitting edges.
6. Spray. Hold the gun 6–8 inches from the surface and square to it, move your whole arm, and overlap each pass by about half. Start moving before you pull the trigger and release it before you stop.

The pressure range, distance and overlap are the general method for HVLP guns, not figures from the Throohills listings.

Choosing a nozzle

Cleaning

Clean the gun straight after use — dried paint in the passages is the usual reason a gun stops spraying evenly. Empty the cup, then spray the right cleaner through it (water for water-based paint, thinner for solvent-based) until it runs clear. Take off the air cap and nozzle and clean them with the brushes in the included cleaning kit; never push a wire through the nozzle, which scratches it. Dry everything before you reassemble it.

The manual, and parts

Several listings name an instruction guide in the box; we found no online copy. The kits come with more than one nozzle size and six strainers, and the gravity guns add fine mesh filters. We found no separate Throohills parts listing — for a lost nozzle or cup, ask the seller through your Amazon order, and give the model (4001, 2008 or H827) and the nozzle size.

Which gun for you

For larger jobs — a car panel in primer, a set of cabinets, a fence — the 4001's 1000cc cup means fewer refills; it is the best seller, with 4.4 stars from 320 ratings shared by its versions. For clearcoat, touch-ups and small parts, a gravity-feed gun wastes less paint and is easier to control. Compare all three on Throohills HVLP spray guns.

Questions

Kit contents from Throohills' own Amazon listings, checked on 2026-09-11. Spraying technique is general HVLP practice.