I don't know if your problem is exactly fixable (ran into it quite a lot at the beginning, don't use low-opacity brushes since than)
Originally Posted by Zimcub
there're a few workarounds - get a custom blender with enabled size dynamics and go over parts than need extra accurate blending
use round camel hair brush - one of my favorites in painter, but you'll need a lot of time to get used to it; also, worked better in earlier versions (it's producing too watered and "oily" strokes since v. X, I blame multicolour sampling code changes, but can't be sure)
or transfer files between painter and PS, since PS brushes are better with transparency.
on the fourth day of glitchmas my painter™ gave to me
four random crashes, three broken brushes, two system hangups & one corrupted workspace