If I Have Stains on My Flat Latex Paint Wall Do I Need Sealant Before Repainting?

About Primers

• A primer is a specially formulated product used to prepare a surface prior to painting. A primer creates a uniform surface that allows the top coat of paint to adhere properly. A primer also prevents paint from peeling and cracking and covers a wide range of stains and flaws. If you are repainting a room and are not changing the color too much, you can usually get by without a primer. However, for big color changes or walls that have stains, a primer is necessary to prevent colors or stains from bleeding through.

Types of Primers

• Primers are available in three types: oil-based/alkyd, acrylic/latex and tinted shellac. Any of the types are suitable for use over latex paint, with each having its own advantages. Oil-based/alkyd primers dry slowly, have a strong smell and release volatile organic chemicals (VOC) and must be used with proper ventilation. These primers are thinned and cleaned up using mineral spirits. Acrylic/latex primers dry quickly and are water soluble. They provide a less-brittle surface than oil-based or shellac primers. These primers are resistant to cracking. Both oil-based and acrylic primers are available in a stain-blocking option that inhibits bleed through of stains. Tinted shellac is a fast-drying primer that uses denatured alcohol for thinning and cleanup. It has a strong odor and is somewhat difficult to use, but it covers severe stains and odors well.

Choosing a Primer

• All primers have a degree of stain-covering ability. The primer you choose depends on the type of stain you have. For minor water-soluble stains or minor water, nicotine or smoke stains, an acrylic stain-blocking primer is sufficient. Because of its low odor and easy cleanup, many people prefer this type of primer. However, for more serious stains, such as lipstick, marker, graffiti or heavy nicotine, use an oil-based stain-blocking primer. Tinted shellac is required for severe stains, especially severe water and smoke stains. The primer seals in the stain as well as the odor.

Application

• Before applying a primer to the wall, the surface must be as clean and grease-free as possible. Lightly sanding the wall will provide better adhesion. After sanding the wall, wipe away any dust particles with a tack cloth or damp rag to get the smoothest possible surface. If your surface is rough after priming, sand it again before painting. Apply paint within a week of priming for best results.