156 The Painting Tools of Scenic Artistry You will find that each sprayer seems to have its own characteristics ­ its own personality, if you will. When doing a spray job, you may find a particular sprayer in the shop that performs just right. If you are in a shop that has four identical sprayers, you can lose track of your favorite. If you name and label these four sprayers John, Paul, George, and Ringo, for instance, or any other names you may be fond of, you can always be sure to find your favorite sprayer again. Also, it is a lot more interesting than naming the sprayers 1, 2, 3, and 4. Aerosol Sprayers Two-part aerosol sprayers that you can load with your own paint are useful for toning, props painting, tight detail jobs, and touch- up. The two parts of these aerosol sprayers are canisters, also called power units, that are fitted with the a spray nozzle and contain the compressed aerosol fluid, and the glass or plastic jar, which the paint will be loaded into. Additional power units can be purchased as replacements. This sounds rather technical, but these tools are very easy to use; you simply fill the jar with a very thin paint or dye, which can be sprayed in the same manner as a can of spray paint. Paint for these sprayers must be strained. Once the power unit is depleted, clean and save the spray tip from a narrow cone shape to a fan. On the back of the gun is an airflow valve that controls the mix of air coming out of the spray tip; the spray will be flattened into a fan shape by mixing air in from the side or not to keep a cone-shaped spray. You can change the direction of the fan pattern by rotating the spray tip at the front of the gun to orient the fan vertically or horizontally. Second, you can change the proportional mix of air and fluid by adjusting the fluid valve, the knob for which usually is located on the back of the spray gun below the airflow valve. The third way to control the spray is to regulate the psi (pounds per square inch of air pressure) entering the tool. Most spray guns are not sold with air regulators, also called air valves, to adjust the air pressure of the spray. However, any supplier of spray guns will sell regulators for compressed air equipment. These attach at the air hose connector at the rear of the gun. I recommend getting an air valve attachment for every spray gun in your shop, as most pneumatic construction tools operate at a higher psi than pneumatic sprayers. Having a valve precludes the need for a regulated air hose or separate compressor. It also gives you greater control over the variables of your spray right at the gun. Purchase a name-brand sprayer from a reputable dealer. Be careful of purchasing unknown brands of spray guns, as