Spray guns for Teflon™ coatings come in a variety of shapes, sizes, and spraying technologies. The most popular guns in Teflon™ coating shops are conventional spray guns, HVLP spray guns, and Trans-tech spray guns. Here we look at the differences…
Conventional spray guns use basic high pressure. The coating is blasted onto the part at this high pressure using an air compressor. The high pressure finely atomizes the spray giving the coating a very smooth finish. Transfer efficiency for conventional spray guns is typically 50% or less.
High-volume low-pressure (HVLP) spray guns increase transfer efficiency, typically to about 65%. This means more of the coating actually makes it to the part instead of being wasted. With HVLP guns, air is delivered at much higher volume than conventional guns, but with a much lower pressure, so that more finish ends up on the part instead of in the air. HVLP guns are compliant with the California South Coast Air Quality Management District.
Trans-tech spray guns use low volume, medium pressure. Transfer efficiencies are normally about 60% or better. Trans-tech guns are the best of both worlds: the finish quality is almost that of a conventional spray gun, with close to the efficiency of an HVLP spray gun. Trans-Tech is used where compliance is not required but cost savings is important.
Here's a handy chart to help you choose:
Spray Gun Cleaning
To clean air caps: Remove the air cap from the gun,
place it in a clean solvent, and blow dry. If the small holes are clogged,
after soaking the cap in the solvent, use a toothpick or some other similar
soft implement to ream the holes. Never use wires or a nail because they can
damage the cap.
To clean pressure feed guns with an attached cup: Turn off the air supply, loosen the cup cover and remove the fluid tube from the paint. Pull the trigger while holding the gun over the paint cup to let the rest of the paint drain back into the cup. Empty the cup and wash with a clean solvent and cloth, then fill the cup halfway with clean solvent and spray it through the gun to wash out the fluid passages. Make sure you spray into an approved, closed container and that you follow local codes about disposing of solvents! Clean the air cap and wipe the gun with a cloth soaked in solvent.
To clean pressure feed gun with a detached cup or tank: Turn off the air supply and open the relief valve. Material in the hoses may be blown back, so make sure the lid is loose and the gun is higher than the cup or tank! Loosen the air cap and pull the trigger until all the material is back in the cup or tank. A gun cleaner should be used to ensure proper cleaning. Place the gun and cups over the nozzles in the cleaner and close the lid tightly. The cleaner will spray solvent through the nozzles, keeping the solvent contained so it can be disposed of properly. Be sure to dispose of the solvent correctly according to local codes.