Graco G40: The Complete Practical Guide to the Air-Assisted Airless Spray Gun
The Graco G40 combines the power of airless spraying with the finesse of air-assisted technology. This guide shows you how to get the most out of your spray gun – from safe setup and optimal spraying technique to professional maintenance.
Product Overview: Technology, Versions & Applications
The Graco G40 (models 262929 & 262932) is a high-performance spray gun designed for professional coating applications. It operates with a maximum fluid pressure of 4000 psi (280 bar) and an air pressure of up to 100 psi (7 bar). Thanks to air assistance, it delivers exceptionally fine, even surface finishes – ideal for paints, stains, and high-coverage coatings.
| Property | Value | Application |
|---|---|---|
| Max. fluid pressure | 4000 psi / 280 bar | Thick coatings, high coverage |
| Max. air pressure | 100 psi / 7 bar | Fine atomization, smooth finish |
| Weight | approx. 450 g | Comfortable work over long periods |
| Materials | Architectural paints, coatings | Interior & exterior, furniture, facades |
⏱️ Faster working time
Air assistance enables higher coverage rates with reduced overspray.
🎨 High-quality finish
Ultra-fine atomization for smooth, streak-free surfaces without orange peel.
🔧 Robust engineering
High-quality materials such as carbide and stainless steel ensure long service life.
Recommended Basic Settings (Guideline Values)
Optimal settings depend on material, tip size, and desired results. The following values serve as a starting point:
- Distance to surface: approx. 30 cm (12 inches)
- Movement: Even, parallel strokes with 50% overlap
- Angle: Always hold the gun perpendicular to the surface (no arcing)
- Air pressure (air-assisted): Start low (approx. 20–30 psi) and gradually increase until “tails” disappear from the spray pattern.
- Fluid pressure (airless): Start at the lowest setting and increase until a uniform, edge-free spray pattern is achieved.
Professional Workflow in 6 Steps
- Preparation & safety: Ventilate the workspace, remove ignition sources, and wear personal protective equipment (eye, respiratory, and hearing protection).
- Connect the gun: Securely connect fluid and air hoses to the gun and sprayer using two wrenches.
- Relieve pressure: Before any change, cleaning, or maintenance, fully relieve pressure according to the pressure relief procedure.
- Install tip & guard: Install the tip (arrow facing forward) and the guard hand-tight.
- Test settings: Test on a sample surface. For air-assisted spraying: reduce fluid pressure until tails appear, then increase air pressure until they disappear.
- Spraying & cleanup: Use smooth movements with 50% overlap. Clean the gun immediately after finishing according to the maintenance plan.
Common Problems & Solutions
| Problem | Cause | Solution |
|---|---|---|
| Irregular spray pattern | Clogged tip/air holes | Clean the tip (use a soft brush/toothpick, no metal!) |
| Tails in spray pattern (air-assisted) | Air pressure too low | Gradually increase air pressure at the regulator |
| Fluid leaking from the front | Seat leaking or guard not tight | Replace the seat (repair kit 249456) and/or tighten the guard |
| Gun remains pressurized | Pressure not fully relieved | Follow the pressure relief procedure precisely; loosen tip nuts very slowly if necessary |
Maintenance Schedule for Maximum Service Life
- Daily: Flush the gun after each shift and store dry. Inspect hoses and connections for wear.
- Weekly: Lubricate the trigger pivot pin and contact points on the gun body (Graco lubricant 111265).
- During color changes/shutdowns: Flush the gun at the lowest pressure with a compatible solvent until all residues are removed.
- Filters: Clean inline filters regularly with a soft brush; replace if damaged.
- Seals: Inspect O-rings and U-cups (e.g. part 7) regularly for wear and replace if leaks occur.
FAQ – Frequently Asked Questions about the Graco G40
1. Which solvents are prohibited?
Do not use 1,1,1-trichloroethane, methylene chloride, or halogenated hydrocarbon solvents. They can react with aluminum components and cause dangerous failures.
2. How do I clear a clogged tip?
Relieve pressure, rotate the tip 180°, spray into a bucket, then rotate back. For stubborn clogs, remove the tip and guard and clean with a soft brush.
3. Why is the pressure relief procedure so important?
Residual pressure can cause serious injury due to fluid injection. Pressure must be fully relieved before any maintenance, cleaning, or disassembly.
4. Can I use the gun for water- and solvent-based paints?
Yes. Use the correct seals: black seals for water-based materials, orange seals for solvent- and oil-based materials.
5. Where can I find spare parts?
Use only original Graco spare parts (see parts list in the manual). They ensure safety and functionality. Spare parts are available through authorized Graco dealers.
Conclusion
The Graco G40 is a powerful and versatile spray gun for demanding coating applications. By understanding the technology, strictly following safety procedures, and performing regular maintenance, you will work more efficiently and safely while achieving professional, high-quality results. Take advantage of air-assisted technology for outstanding finishes and extend the service life of your equipment through proper care.
