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Spraying with a Spray Gun – Distance and Direction

Keeping the spray gun the correct distance from the car’s surface is vital to getting the paint results that are needed for the job. Holding the air cap too close to the panel will result in too thick a layer of paint – which will then sag, run, and create large, raised streaks and channels in the paint’s surface once it dries. Even slightly too thick paint can result in the countless thousands of tiny nubs which make up “orange peel” texture. On the other hand, if the air cap is separated from the car’s surface by too large a span of air, then the paint will go on too thinly and will be more fragile than it ought to be – an equally undesirable result.

The correct distance to hold the nozzle from the car’s surface varies by the type of spray gun you are using. If you are employing a standard, high-volume high-pressure siphon cup type, of the kind that has been in use since nearly the earliest days of auto painting, then the nozzle should be kept 7 to 8 inches distant from the sheet metal – about one hand-span. If, on the other hand, HVLP or LVLP equipment is being used, keep the spray gun half that distance from the metal – roughly 4 inches or so. You can adjust the exact distance based on observation of the sprayed areas.

Another very important consideration in spraying color onto your car with a spray gun is the direction of air flow in the workspace. All painting workshops – whether these are carefully-constructed spray booths or simply your garage with a layer of plastic on the floor and the interior carefully cleaned – need to have a ventilation system set up. Otherwise, the overspray could build up to the point where even the scuff of a foot or the flip of a light switch could trigger a detonation.

The ventilation system, naturally, creates a steady suction of air in one direction. This is also the direction that you should paint your car in. If the nose of your car is pointed at the ventilation inlets, and the rear end is pointed towards the exhaust vents, then you should start painting at the front of the vehicle and work your way towards the back.

There is a simple reason for this. The inevitable clouds of overspray will move in the direction of the ventilator air flow, speckling the surface of the car with tiny dots of color. This is moot when it occurs on as-yet unpainted areas – after all, they will soon be painted over, and the dots will dissolve into the overall layer of paint with its solvents and thinners. However, when these freckles of paint fall onto an already painted area, they can leave hundreds of tiny salt-grain-like imperfections where each dried on the surface, creating a small raised area with a clearly defined edge. This is an undesirable result, but fortunately, it is easy to avoid.


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