Question

paints are offten stirred before use.why?

Answer 1

because if paints sit for long they start to get a film on the top, this film will make the top darker or ligher then the center. If you don't mix it, then when you actually use it on the surface you are painting on it will dry in tones and look splotchy. Depending on the type of paint you used, it may peel because the paint dried at a differient rate across the canvis or wall as well

Answer 2

they is mixed by good strring