Because it's binder or solvent base evaporates.
What dries fast is not so much the paint, but the fresh plaster on which the fresco paint is applied. And as the plaster dries the paint unites with it.
Only if it dries out.
paint drying in sun
The word is spelled dries. Example: Watched paint dries slowly.
Most paint dries faster on wood.
semi gloss
Your paint should dry to the exact color of the sample, if it does not, the color was mixed wrong. When you apply a fresh coat of the same color paint, it goes on lighter, and darkens as it dries.
as long as you don't spray in the air pipes
Generally, water based paint dries faster.
If the paint is not dry, yes. Just use dish soap and warm water. Rinse well. If the paint dries, probably not.
Enamel paint dries well on plastic. If you only need a small amount, model paints as sold in hobby stores give a great selection of colours.
As paint dries through the process of oxidation the reaction produces heat, which is an exothermic reaction.