A Primer on Primers

Primers have 2 basic purposes— to promote adhesion and to seal porous surfaces. Primers can be formulated for either purpose, or in the case of many primers, both.

As a general rule, a bare surface should be primed. Surfaces such as wood or masonry are relatively porous, and a primer will promote a more uniform finish.

Primers can also be used to improve adhesion over hard, slick surfaces. (Other methods, such as mechanical abrasion can also be used.)

Specialty primers are used for particular problems or situations. For example, drywall repair clears are used to improve the soundness of damaged drywall. Primer/ sealers are also used to block stains.

It is seldom necessary to prime previously painted surfaces. There are occasional situations where this might be necessary or beneficial, such as when it might be more efficient to primer rather than degloss a surface.