While the art of painting with a HVLP spray gun can take years to perfect, the information in this how-to can get you started in the right direction.
Initial Setup Of Your Spray Gun
For your beginning settings you will want to have the cup attached to the gun. Now would also be a good time to mix the KBS #1 Thinner with your chosen KBS paint. All KBS paints will need to be thinned (except Fusion) by a ratio of between 5-10%. It's always a good idea to use a strainer when pouring paint into the cup, because even though KBS Paint is some of the finest on the planet, we know stuff happens, and a little prevention can go a long way.
On most guns you will have two control knobs. The upper, which is the fan control and the lower which is the fluid control. For your initial setup you will want to turn both of these so that they are fully in the closed position. Now you can connect the air and set the regulator to the recommended pressure as stated by the gun manufacturer. Both the fan control and the fluid control can be fully adjusted as you see fit, but for now it's a good idea to start with both of these backed out until you see the first thread.
While spraying against a test object (card board works good) adjust the fan knob out (counter clock-wise) until you get a nice long fan shape of around 20-25 cm. You will also be watching to see how much fluid is coming out. What you want is an even wetness. If what you're getting is uneven, spotty or dry looking, you'll want to open up the fluid knob. You can use full turn increments to get close and then dial it in from there. Remember, too far and the paint will be spraying too thick which means it will run or sag.
The Skill of Spraying
Now that your gun is adjusted, let's talk about what makes up good spray gun technique, but before we do don't forget that with good gun technique comes good safety. Always use a high quality air respirator when using a spray gun. Safety glasses are also advised.
The first part in spray gun technique is Gun Distance. Proper shooting distance varies between fast drying products such as lacquers and slow drying products such as enamels. The majority of KBS paints are fast drying so you will be looking for a distance of between 15 and 20 cm, tip to surface. However if you are spraying a slow drying paint, such as an enamel, you will want to be further away, somewhere around 20 and 25 cm. The difficulty arises in maintaining that equal distance when you move your gun from side to side. The focus is on a set sliding motion, rather than pivoting your arm at the elbow, which feels more natural. This is where the second part of good gun technique comes into play, which is Gun Angle.
Gun Angle, just as with distance, needs to stay the same through each stroke. The angle you're looking for is 90 degrees, but this can sometimes be confusing. What we're talking about here is to make sure that the gun is pointed directly at the surface you're painting, without angling to either side. Your wrist will naturally want to remain stiff but by bending it at the beginning and end of each stroke you can keep the gun pointed at a right angle to the surface being painted and after a little practice you'll find it becomes easier.
The third part in good gun technique is Overlap. What we're talking about here is the amount of area that is re-covered with each following stroke. The common mistake would be to have zero overlap and line up the top of your second stroke with the bottom of your first. If you were to do this it would result in hard edges and spotty coverage. A good rule of thumb is to use a 50% overlap rule. For example, if each row is 25cm tall, each following row will overlap the last by about 12.5 cm. This ensures good coverage while minimizing any appearance of hard edges.
Now we come to the final two parts in good spray gun technique which both accomplish the same thing in different ways by controlling how much paint hits the surface with each stroke. These final two parts are Gun Speed and Trigger Control. While easy enough on their own, Gun Speed and Trigger Control can add that extra element in difficulty much like trying to pat your head and rub your stomach at the same time. So donâ€™t worry if it takes a little time to get used to it.
Gun Speed, is simply the rate at which you stroke the gun back and forth. With this there is no set rule and can be whatever feels most comfortable, as long as it remains constant. Remember to adjust the fluid knob. If you prefer a slower, more even stroke, you will want less fluid. Or if you prefer to move faster you will want more fluid.
The same is true with Trigger Control. On most guns, the trigger operates in two stages. As you begin to depress the trigger, this starts the flow of air. Pull it further and the fluid is engaged until it is at its maximum- which is whatever you set the fluid knob to. With good trigger control, or feathering, the idea is to get the air flowing and engage the fluid just before your stroke meets the edge of what you're painting. Again, remember to adjust the fluid knob if a fully depressed trigger is giving you too much paint. Because you want a uniform amount with each stroke, a fully depressed trigger is always your goal.
Nothing clogs moving parts like paint when it hardens. Properly cleaning your spray gun after each use will keep it working smoothly and directly affect your finished product the next time you use it.
Make sure to disconnect the air hose first, not only for safety but also because you don't want paint spraying in your face. Disconnect the cup and let any remaining paint drain back down the pick-up tube and back into the cup. Properly dispose of any remaining paint in the cup. Never pour used paint back into the can. This is because KBS RustSeal is a moisture cured urethane, and exposing it to moisture can start the curing process, and you don't want that mixing with what is left in the can.
Clean the cup using the KBS #1 Thinner and a clean rag. Never use lacquer thinner as this will remain in the gun and prevent good adhesion the next time you spray. Fill the cup to halfway with KBS #1 thinner, re-attach the air hose and spray it through to fully clean the lines. Once this is done, unscrew the air cap (the piece that screws over the tip) and soak it in clean solvent until the material loosens and flows out easily. If you find it necessary to use something to force the holes clean, always remember to use a material that is soft like a tooth pick. If you were to use a hard object like metal it can enlarge the holes and cause huge problems for your spray pattern.
Last in the sequence of cleaning is to lubricate your standard three points using a non-silicone, non-petroleum spray gun lube. The first three are the air valve packing, the fluid needle packing, and the trigger bearing screw. The fourth item, the fluid needle spring, should be lubricated using petroleum jelly and is located inside of the gun behind the fluid adjustment knob. Follow the manufacturer's original instructions on how to disassemble and reassemble the gun to access each of these four points.