Question：Interior Painting Problems: Poor Flow and Leveling?
Using lower-quality paint can lead to this problem. In addition to the quality of the paint, a number of other things can cause poor flow and leveling:
Applying additional paint to "touch up" partially dried areas.
Re-brushing or re-rolling partially dried areas.
Using the wrong type of roller cover or poor quality brush.
Top-quality latex paints are generally formulated with ingredients that enhance paint flow. Brush and roller marks thus tend to "flow out" and form a smooth film.
When using a roller, be sure to use a cover with the recommended nap length for the type of paint you are applying.
A high-quality brush is a must, since a poor brush can result in bad flow and leveling with any paint.