The base may just use a Reducer{not laqure} to thin it out to a sprayable paint with not bring to thin or thick state. So you need to know what thinner it is and how much.
Or it may be like PPG base that does that but also is "reactive reducer{like a hardener does}
It will also go on in 3-4 coats almost dry to just give the color.
Some base shoots dry as a laqure would.
Some go on wet looking but flash to a dull look.
Basicly you are just coloring the suface with the base and they clear gives the shine.
Lights coats of base are hard to make run and if ypu get some in the clear they are easy to sand out.
Thats why I do not understand the guys that post the are shooting single stage on door jambs,under hood,inside trunk,engine bay.
And Base clear on the put side. Gives a bad paint line, as well as differant shade.