Priming and Sanding Walls Before Painting
If you’re working with new walls, or if you’ve patched any holes before you start, you’ll also need to prime. Primer fills in spongelike pores and creates an even, solid base that takes paint well. You should also prime if you’re going from a dark to a light color or vice versa. (In the latter case, have the paint store tint the primer to go with your wall color. It will save you at least one coat of paint later on.) Primer should also be sanded before the paint goes on the wall; for a top-notch job, sand between paint coats, too.
