How-To Guides
Everything you need to start spraying well and make smart equipment decisions — written for real beginners and improving painters.
HVLP vs LVLP: What Each Format Costs You in Air and Hands Back in Finish
LVLP draws roughly half the air: about 6-8 CFM continuous at the inlet on a 1.4 mm setup against 12-14 CFM for the equivalent HVLP conversion gun. On thin material the two lay almost identical film. The gap only opens on high-build primer, where the LVLP ran out of atomising energy and the peel grade fell off a cliff.
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Every Airless Tip Number Decoded: Orifice, Fan Width and the Coating It Was Built For
The first digit doubled is the fan width in inches at 12 in from the surface. The last two digits are the orifice in thousandths of an inch. A 517 is a 10 in fan through a 0.017 in hole; a 311 is a 6 in fan through 0.011. Fan width sets how fast you cover; orifice sets how much material and how much sprayer you need behind it.
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Fluid Tip Sizing by Coating: The Decision You Make Before You Pull the Trigger
Thin coatings want 0.8-1.3 mm, mid-body coatings 1.3-1.5 mm, high-build primer 1.6-2.0 mm, and reduced latex 1.8-2.5 mm. Tip diameter is set before every other adjustment and constrains all of them. Go too small and the film comes out starved and peeled; too large and it runs before it flows.
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Reduction Ratios That Actually Sprayed, and the Cup Reading They Produced
Most solvent coatings spray between 15 and 22 seconds on a Ford #4 cup; reduced latex through an air gun lands nearer 35-45. Ratios that hit those numbers are logged below alongside the shop conditions they were mixed in, because a 4:1:1 clear at 72°F and the same 4:1:1 at 88°F are not the same coating.
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Will Your Compressor Feed the Gun? Measured Draw Against Delivered SCFM
A 1.4 mm HVLP conversion gun draws a continuous 12-14 CFM at the inlet; an LVLP of the same tip size draws 6-8. Size the compressor at roughly 1.4 times the gun's continuous draw at 40 psi, not at 90, and expect a 60-gallon single-stage to run almost non-stop behind a full-size HVLP gun.
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Spray Defects, Traced Back to the Setting That Caused Them
Nearly every spray defect is one input outside its window: distance, pressure, reduction, reducer grade, film thickness or flash time. Orange peel and solvent pop sit at opposite ends of the same axis. Fisheyes and dirt are the exceptions — no setting fixes contamination.
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HVLP vs Airless Paint Sprayer: Atomisation Measured Side by Side
Airless has no air in it — a pump forces coating through a carbide orifice at 1,200 to 3,300 psi and the fluid tears itself apart on velocity alone, leaving droplets around 70 to 150 microns. HVLP shears the same coating from the outside with air capped at 10 psi and lands droplets roughly half that size. Coarse droplets build fast and read textured; fine droplets build slowly and read close to glass.
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Which Sprayer for Which Job: Square Footage, Coating Viscosity and Overspray Tolerance
Three constraints decide it: how much area you are covering, how thick the coating is out of the can, and how much overspray the space will tolerate. Under about 300 sq ft with a thin coating, a cup gun wins. Over about 1,500 sq ft with unreduced material, airless wins. Overspray tolerance overrules both — an occupied room sends you back to a cup gun regardless of area.
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HVLP Spray Gun PSI Settings: Starting Pressures and the Cap Number They Really Produce
Set 26 psi at the gun inlet with the trigger pulled and you will read about 9 to 10 psi at the air cap on a typical 1.3 mm gravity gun — and cap pressure is the number that atomises and the number that makes the gun legally HVLP. Most coatings hold a usable window five to nine psi wide at the inlet. Below it you get peel and sags; above it, dry spray.
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Paint Viscosity Chart for Spraying: Ford #4, Zahn #2 and How Each Reading Sprayed
Most spray coatings land between 15 and 30 seconds on a Ford #4 cup, and in that range a Zahn #2 reads within about a second of the same number — they only diverge above 50 seconds. Every ten degrees Fahrenheit of warmth takes roughly half a second to two seconds off the reading, which is why the same mix sprays differently in the morning.
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How to Clean an HVLP Spray Gun: Strip, Flush and Rebuild Intervals
Flushing after every session is the minimum, not the maintenance. A gun needs the air cap and fluid nozzle pulled and soaked roughly every 8 sprayed hours, a full strip every 40, needle packings around 100 to 150, and a matched needle-and-nozzle set somewhere between 300 and 500. Miss the packings and the gun starts dripping; miss the cap and the pattern goes lopsided.
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Paint Sprayer Transfer Efficiency: Where the Other Half of Your Gallon Goes
Transfer efficiency is the fraction of what leaves the gun that lands and stays on the work. A conventional siphon gun runs about 30 to 40 percent, airless 40 to 50, HVLP and LVLP 60 to 70, electrostatic higher still. On 1,000 sq ft at 2 mils dry, the gap between 35 and 65 percent is roughly three and a third gallons of coating you bought and sprayed into the air.
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