Page 62 - Australasian Paint & Panel Magazine

SPRAY GUNS
SET TO IMPRESS
Spray gun setup is crucial to a consistent result so why do some painters stubbornly stick to bad habits, asks John Hristias, PPG Business Support Manager Asia / Pacific.
THE MARK OF a skilled painter is the ability to consistently produce a quality end result, time after time. In order to do this, the technician needs consistency in how they approach each job. By this, I mean aiming for exactly the same product mixing process, spray environment and application technique, as well as one factor the technician should have complete control over – precise spray gun setup. Get it wrong and it is a recipe for reworks. For example, a high inlet air pressure makes metallic particles stand up, leaving a darker appearance on the angle and creating a halo around blend edge. Other issues include mottle and ‘basecoat profiling’, along with lose of transfer efficiency – coverage takes more coats and product so cycle-time and job
cost blow out. Low pressure also causes problems (particularly with clearcoats), such as solvent boil, soft film and poor final appearance. And adjustment of the ‘fan’ and ‘material’ settings
is just as crucial.
62 PAINT&PANEL July / August 2018
THE SOUND OF REWORK
Some painters reckon they can judge the correct inlet air pressure by pulling the spray gun trigger and listening. It is simply not possible, given that so many things can vary – every gun makes a different sound, the fan adjustment changes the sound, the spray booth and workshop is often noisy and they might even suffer from a touch of industrial deafness. I have had technicians set their pressure using that method and, when checked with a gauge, it was way out.
SET TO IMPRESS
PPG’s Australian and New Zealand refinish teams have put a lot of time and effort into spray gun setup to suit our products and our customers. We have tested, hone and tuned the SATA spray gun setup to make sure customers get consistently great performance. Whatever brand you use, make sure your spray gun is cleaned thoroughly and adjusted precisely before starting each job.
Inlet air pressure – The number one priority is a method of accurately measuring inlet air pressure. The simplest solution is a SATAjet DIGITAL model where the gauge is actually built into the gun handle – their popularity shows that plenty of technicians recognise the advantages. Retro fitting a SATA adam2 digital gauge does a similar job. If you don’t have a SATA gun, at least use a suitable inline gauge.
Fan – Altering the fan affects air pressure – narrowing tends to increase pressure, while opening it reduces pressure.
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