PPG Tech Tips – Choosing the best spray gun for each job
John Hristias – PPG Business Support Manager Asia/Pacific
Naturally, the spray gun is a painter’s most important piece of equipment. However, there’s no such thing as a universal spray gun for every application – the modern refinish process is far too specialised. Think about a mechanic – there’s no way they’d get by just using a shifting spanner. It’s the same for refinish technicians – you won’t believe how much easier it makes the job.
Does and Don’ts
Three guns should be the minimum (priming, basecoat and clearcoat), as well as different nozzle sets. Go for top quality – over a long lifespan it’s inexpensive. For example, PPG recommends SATA, a global leader in spray equipment. SATA spray guns integrate perfectly with our processes and deliver outstanding results. Whatever guns you use, make sure they’re cleaned thoroughly and well looked after to keep them at peak performance. Using the right gun brings advantages including reduced product consumption, reduced cycle time and virtually eliminating the risk of contamination.
- Don’t prime with an old topcoat gun. Because they don’t atomise too well, it can take four or five primer coats. That’s lots of flash-off time between coats, as well as inconsistent film-build which can lead to issues such as shrinkage.
- Don’t prime with your topcoat gun. If not cleaned spotlessly, you risk even a few specks of primer ruining your topcoat or clearcoat finish.
- Do choose a purpose-designed primer gun, like the SATA B100RP. It’s inexpensive compared with a topcoat gun but its excellent performance means you can apply primer in just two or three coats, it lays down smoothly so there’s often no need to sand and it’s ideal for the high productivity Wet-On-Wet process.
Basecoat and clearcoat
- Don’t use the same gun for basecoat and clearcoat. It not only compromises both applications, it can easily lead to clearcoat contamination if just a speck of colour is left after cleaning.
- Do choose separate guns – the high performance SATAjet 5000 B is perfect. HVLP technology works best for basecoat because it helps apply colour more evenly so blends are easier, there’s less risk of mottle and it tends to use less product. For example, a HVLP 1.2 fan setup makes it easy to apply difficult colours, such as coarse silvers and charcoals. For clearcoats, RP technology is great for helping to accurately match the OEM finish. For best results, it’s also a good idea to switch between different nozzle setups depending on whether you’re using a ‘medium solids’, ‘high solids’ or ‘ultra high solids’ clearcoat. Note: The PPG Training Team can help you make the right selection.
- Do use a gun specifically suited to small job, such as the SATAminijet® 4400 B. This feature packed gun is basically a compact version of full size SATA models so it’s super-efficient and easy to use.