Cleaning your spray gun immediately after applying roof paint is one of the most important maintenance habits you can develop — dried paint in the gun can ruin tips, needles, and fluid passages, turning an expensive tool into scrap. The good news is that with the right technique and a bit of discipline, a thorough clean takes only 15–30 minutes.
Why Cleaning Immediately Matters
Roof paints — whether acrylic water-based coatings or solvent-based products — begin to cure as soon as they hit air. Acrylic roof paints (the most common type in NZ) are particularly tricky because once they dry, they form a tough, flexible film that is very difficult to dissolve. Leaving paint in the gun overnight, or even for a few hours on a warm Canterbury or Hawke's Bay summer day, can block the nozzle, needle, and air cap permanently. Always start cleaning the moment you finish spraying.
What You'll Need
- Appropriate cleaning solvent (water for water-based paints; mineral turpentine or the manufacturer's recommended solvent for oil- or solvent-based paints)
- Cleaning brushes (a dedicated spray gun brush kit with various sizes)
- Soft cloths or paper towels
- A spray gun cleaning pot or a clean bucket
- Protective gloves and safety glasses
- A well-ventilated workspace
Step-by-Step: Cleaning After Water-Based Roof Paint
Most NZ roof paints — including popular products from Resene and Dulux — are water-based acrylics. Follow these steps:
1. Empty and flush the cup or pot
Pour any remaining paint back into the tin, then add a small amount of clean water to the cup. Spray this through the gun into a waste bucket until the spray runs clear.
2. Disassemble the gun
Remove the fluid tip/nozzle, needle, air cap, and cup. Refer to your gun's manual — most quality airless or HVLP guns have a similar layout, but details vary by brand.
3. Soak and scrub components
Place the tip, needle, air cap, and any other removable parts into a container of clean water. Use your spray gun brush kit to gently scrub each part, paying close attention to the fluid tip orifice and the air cap holes. Never use wire brushes or metal tools — they will damage precision surfaces.
4. Clean the body and passages
Wipe down the gun body with a damp cloth. Use a small brush dipped in water to clean the fluid inlet and any internal passages you can reach.
5. Final rinse and dry
Rinse all parts under running water, shake off excess, and lay them on a clean cloth to air dry. Lightly lubricate the needle packing and any O-rings with a drop of the manufacturer's recommended oil before reassembly.
Step-by-Step: Cleaning After Solvent-Based Roof Paint
If you've used a solvent-based roof coating, substitute mineral turpentine (or the specific solvent recommended on the product data sheet) for water in every step above. Always check the paint tin or technical data sheet — Wattyl and other manufacturers publish these online.
Safety note: Solvent fumes are flammable and harmful to breathe. Work outdoors or in a very well-ventilated area, away from any ignition sources. Wear chemical-resistant gloves and safety glasses. Dispose of solvent-soaked rags and waste solvent responsibly — check with your local council for hazardous waste disposal options. See WorkSafe NZ for guidance on safe handling of hazardous substances.
Cleaning an Airless Sprayer
If you used a high-pressure airless sprayer (common for large roof jobs), the process is similar but involves flushing the pump, hose, and gun together:
- Place the intake siphon tube into a bucket of clean water (or solvent).
- Engage the prime/flush valve and run the machine until clean fluid comes through the gun.
- Remove and clean the spray tip and tip guard separately — these are precision parts and block easily.
- Flush the hose a second time with fresh water.
- Store the pump with a small amount of pump-storage fluid (often a light oil or manufacturer-supplied fluid) to prevent corrosion.
Always engage the trigger safety lock and relieve pressure before disassembling any part of an airless sprayer. High-pressure injection injuries are extremely serious — treat the gun as you would any pressurised tool.
Common Mistakes to Avoid
| Mistake | Why It's a Problem |
|---|---|
| Leaving paint in the gun overnight | Paint dries and blocks passages permanently |
| Using the wrong solvent | Can damage seals, O-rings, and coatings |
| Using metal tools to clear the tip | Damages the precision orifice, ruining spray pattern |
| Skipping lubrication on reassembly | Causes needle packing to wear prematurely |
| Incomplete flushing of hose (airless) | Dried paint in the hose restricts flow next time |
Storing Your Spray Gun
Once clean and dry, store the gun in a protective case or hang it safely. Keep it away from dust and direct sunlight. If storing for more than a few weeks, lightly oil all moving parts and wrap the tip in a clean cloth.
When to Call a Professional
Spray painting a roof is physically demanding and technically skilled work — working at height adds significant risk. If your gun is already blocked with dried paint and home cleaning hasn't cleared it, a professional spray equipment repairer can often salvage it using ultrasonic cleaning. For the roof painting itself, a qualified roof painter will have commercial-grade equipment, the right safety gear for working at height, and the product knowledge to get a long-lasting result. You can find experienced local roof painters on tradedirectory.co.nz.
Always ensure any roof work complies with the NZ Building Code and that workers are following safe work at height practices as outlined by WorkSafe NZ.
Sources & Further Reading
- Resene – Paint technical data sheets and application guides
- Dulux NZ – Product information and painting guides
- Wattyl NZ – Roof coating product guides
- WorkSafe NZ – Hazardous substances and working at height
- BRANZ – Building research and best practice guidance
- MBIE Building Performance – NZ Building Code
Master Painters NZ member
Licensed Building Practitioner (LBP)
Roofing Association of NZ (RANZ)
