The most common question in the paint industry is: Which temperature/speed should I use?
The temperature/speed should correlate to the temperature of the body panel you’re painting. The temperature of your booth (or garage) will have an effect on this. If you’re spraying in high humidity, you’re going to want to go with a higher temp (slower) as it’ll allow the solvents to evaporate (flash off) better. This reduces the chance of having solvent pop. If you’re spraying smaller parts you can get away with using a lower temp (faster), but understand that it will also have an effect on the flow out (leveling) of your paint. The slower the reducer the more time the paint has to flow out, equaling a more smooth finish.
Much like reducer, the slower the activator (higher temp) the more time your clear has to flow out (self level) resulting in a much smoother (wetter) finish.