Being HVLP and low VOC products are the way the industry's going I will be referring to them in this discussion on painting and paint guns. Most all Automotive Restoration Training basics dealing with HVLP can be applied to conventional guns, atomization is atomization. The HVLP just arrives at it differently. You have two things that help you with this process, air and solvent. Solvent can mean something that is already in the PSPR from the manufacture or something the manufacture has told you to add to it. By the way, you should always mix in proper ratios as instructed in the tech sheet. The thinner (less viscosity) you get the PSPR or the more air you have at the fluid tip of the gun the more it will break up the PSPR. The target for you is getting the perfect balance needed. Too much solvent and the PSPR will have no body, fill, durability, etc. Too much air and you blow the PSPR everywhere but the car, poor adhesion, excessive texture, etc.