Preparing
Primer - the first step toward a lasting finish. To get a great-looking finish coat and the beautiful, long-lasting results you expect, be sure to properly apply primer to the surfaces you plan to paint.
Sherwin-Williams primers are formulated to solve typical painting problems while helping to make your finish coat smooth and uniform:
Achieve a smooth, professional finish
Block stains, marks and odors
Assure adhesion
Speed topcoating
Prevent peeling
Attain the truest paint color in the fewest coats
Improve touch-up performance of the topcoat
In general, the only time a primer is not needed is if you're re-painting a surface that's in good condition.
Your neighborhood Sherwin-Williams paint expert can provide additional advice about selecting and applying the right primer for your project.