I have a wall that is 8 feet tall and about 20 feet wide with a strip of chair rail that runs the length of the wall. I used Sherwin Williams satin white paint. I gave the wall a light sanding with fine sand paper before I painted. I cut in the top, bottom, and the chair rail with a brush. Then rolled on the paint with a Purdy roller. The wall is now full of streaks (even after a second coat). I used the "W" technique (always worked fine for flat paint). I plan to repaint it again with the sa...