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There are needs for other tips. For instance,HVLP spray gun when shooting polyester primer you may need as big as a 2.3, but for urethanes and epoxies, the 1.3 or 1.4 will work great. If you plan on using a pressure pot or painting a bus, all bets are off and we would need to study a little bit more. As an example of the use of a 1.3 tip, I did a test once that proved the point well. I shot two panels of metal with a medium solids urethane primer. One was shot with a 1.3 super high atomizing top of the line topcoat gun. The other was shot with a 1.5 (or a 1.7 I can't remember) "hoser" primer gun. Three coats were applied and after a full cure (the one shot with the larger gun took MUCH longer to flash and cure by the way) the film thickness was measured. The one shot with the 1.3 tip was 2 tenths of a mil thicker! The larger gun laid out the marble sized droplets full of solvent, and when the solvent flashed the film shrank. You need to "tune" your gun EVERY TIME you use it, just as you would tune a guitar before you perform. This is done with a very basic sprayout pattern test. This very basic test tells you how your gun is atomizing and you adjust it to achieve the best atomization you can. Let's do a spray pattern test: Set the fan width as needed (you don't want to change it after you have "tuned" the gun). Turn out the material knob about 2 1?2 turns. This is the "mixture" adjustment, kind of like the idle screw on a carburetor. The farther in it is screwed the lower the fluid to air ratio is and the smaller the droplets will be. The farther out it is, the higher the fluid to air ratio is and the larger the droplets. Set the air pressure at the inlet to the gun to the manufacturer's specs. On an HVLP gun, this spec is usually found on the gun, and is the maximum PSI it can have while still maintaining the maximum 10 lb at the cap for legal HVLP transfer efficiency (68 %). You are now ready to do a test sprayout. Tape a piece of masking paper on the wall for the test. Hold the gun at a right angle to the wall, just as if you were going to paint the wall. Hold the gun at a spread out hands distance (about 8 inches, or 22 centimeters). Pull the trigger to completely open for a split second and then close it. You want an ON-OFF wide open-completely closed in ONE movement. You should have a cigar shaped pattern with complete coverage in the center with fading coverage going away from the full coverage cigar shape in the center. The center should be fully covered without any runs. If you have runs,jhgfygcuh either you are holding the trigger too long, you are too close, or the HVLP spray gun is simply applying too much material; in which case you need to screw in the material knob or turn the air pressure down. But most likely if you have turned the material knob out the 2 1?2 turns and the air is set at the factory specs, you are just too close or holding the trigger open too long. WEB:http://www.chinapaintsprayer.net
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