As we’ve said, applying primer is very important because it creates a bond between the paint and the surface you are painting. If you are painting on a raw surface, one that you have repaired, or one that has a glossy finish, your paint job will be uneven and coverage will be spotty if you don’t prime your surface. Priming ensures that the paint will be absorbed evenly.
Primer is available in different varieties and each one has a specific purpose. We’ve given you some of our recommendations, but keep in mind that there are many different brands available for each type of primer. You can ask for recommended brands at your home improvement store.
Priming new drywall or concrete: If you are painting over new drywall or concrete, you must use a latex primer, which is water-based. If you use an oil-based primer (also called an alkyd primer), the surface of the drywall will be too bumpy to create a smooth paint finish.
Priming raw wood: If you are painting over raw wood (wood that has not been “cured” or dried out), use shellac as a primer. Shellac is a heavy-duty, alcoholbased sealer that will seal the resins in the wood. If they are not sealed, the resins will bleed through the paint finish.
We recommend B-I-N by Zinsser, which is a stain-blocking shellac. While other primers are applied in the same way as regular paint, you should apply shellac using a foam brush. Be sure to get plenty of shellac on the brush and apply good coverage over knots in wood. Also, remember that shellac is toxic, so be sure to work in a well-ventilated area.