With the controls set, air supply connected to the spray gun, and fluid in the cup, you are ready to spray. Begin by checking the spray pattern on a piece of masking paper that has been taped to a wall or other flat, vertical surface. Depending on the spray gun you are using, you'll need to set the air pressure according to the recommendations. For example, if you are using the SATA KLC-B HVLP, you'll need to set the inlet pressure to the recommended 29 psi. You are looking for an elliptical spray pattern with a full, wet center and an outer edge consisting of very small, consistent droplets of paint.
If you look at the spray pattern pictured in the photo on page 92, you can see the small droplets of paint get much larger when the correct air pressure (psi) isn't being provided to the spray gun. Insufficient inlet pressure leads to low pressure at the air cap, resulting in larger droplets or lack of atomization. Proper atomization is the result of a balance between fluid delivery and air pressure. If you have an unsatisfactory spray pattern, as pictured, there are two basic ways to make improvements: One, the air pressure can be increased resulting in better atomization or, two, the fluid control knob can be used to decrease fluid delivery, also resulting in better atomization. A lower amount of fluid delivery will result in a smaller spray pattern but will help to achieve an even spray pattern with fine atomization.
As you can see, following these simple steps will enable you to achieve optimum performance out of your spray gun for perfect results.