ok i found a very easy way to get rid of that filmy white streaks that come from dry brushing and palette knife use. this is what you do. take the oil brush and turn the pressure up a good bit/ then turn the thinner up all the way and load to 0% and have insta dry on. it will not work with out the INdry on. then just gently smooth over the marks and they quickly go away. This has made a world of difference for me even works on jet black.
-hope this helps