More Air Problems with Spray Guns

The hiss of escaping air is not a sound any painter wants to hear when they do not have their fingers on the trigger of their spray gun. That slight, sinister noise indicates that something is seriously amiss with the device, which must be rectified if the implement is to work properly. After all, strong, steady, predictable air pressure is the foundation of spray gun operation, so unpredictable variations in the air pressure – or loss of air pressure – can seriously harm performance and the quality of the finished paint.

If the air leaks out around the fittings – places where the different components of the spray gun fit together, such as the air hose attachment or the air cap – then the cause may be incorrect tightening; this is easily corrected by screwing the hose, air cap, etc. into place more firmly. Before screwing the fittings on more tightly, however, you should check to ensure that they are not improperly-threaded, with the fitting attached askew. This is all too easy to do, and trying to force the fitting on more tightly while it is cross-threaded can produce severe damage to your paint gun.

 Alternatively, the threads may just be permanently loose, possibly because of wear over time or poor machining straight from the factory. In this case, the corrective measure is to wind a little Teflon tape around the threading, then screw the fitting into place over it – the tape will act as “chinking” to keep the air from escaping. This is a method often used in plumbing, and what is effective for water is also effective for air. However, be very careful when cleaning the fitting coupling to remove all scraps and traces of the Teflon tape, lest it return to haunt you by clogging an orifice in the air cap or even the nozzle itself.

If the paint cup is pressurized and air leaks from it, then the problem may be dirt or wear. The gasket sealing the cup should be examined – cleaned if dirty and replaced if simply worn. Generally speaking, air leaks are less numerous than material leaks, although some material problems are also caused by air system difficulties.