Do professional painters dilute paint?

Do professional painters dilute paint depends on paint type, sprayer type, and conditions, but generally professional house painters using airless sprayers do not dilute latex paint, while automotive painters and those using HVLP do dilute or reduce paint as part of normal mixing. For house painting with airless sprayers like Graco 390, 490, professionals typically spray latex paint unthinned directly from bucket because airless pumps at 3000 PSI can handle thick paint, and thinning reduces coverage, causes runs, and voids warranty, so they do not dilute unless paint is extremely thick or cold, or manufacturer recommends up to 10 percent water for priming. For HVLP and LVLP spray guns used for trim, cabinets, and automotive, professionals always dilute or reduce paint, as HVLP needs viscosity around 20 to 30 seconds, so they thin oil-based enamels 10 to 20 percent with mineral spirits, lacquers with lacquer thinner, and automotive basecoat and clearcoat per mixing ratio like 1 to 1 with reducer and hardener. For rolling and brushing, pros may add small amount of water or conditioner like Floetrol to improve flow, especially in hot weather, but not much. So pro house painters with airless usually do not dilute latex, while auto and fine finish painters using HVLP always reduce paint per instructions for proper atomization.