Magazine article Journal of Property Management

A Short Primer on Primers and Sealers

Magazine article Journal of Property Management

A Short Primer on Primers and Sealers

Article excerpt

To get the best exterior painting results, it's often necessary to use a primer or sealer before applying the paint. Priming provides two important benefits: It maximizes adhesion of the finish coat, which adds to the life of the paint job, and it provides a uniform sheen to the finish coat, which adds to the appearance of the paint job. Some primers also block stains from appearing on the surface being painted. Still others inhibit rusting and corrosion of metal surfaces.

Deciding when to use a primer or sealer -- and what type of product to apply -- can be intimidating to many building owners and managers. However, a working knowledge of these specialty coatings can be a valuable asset, regardless of whether you use an in-house crew or an outside contractor.

Primers Improve Adhesion

Primers are specially formulated coatings that perform several valuble functions. First, they adhere to the surface better than paint and make the surface more uniform. Then, when the paint is applied, it 'grips" better than it would on the bare surface. Improved adhesion reduces the chance of paint failure by blistering; peeling or cracking, which, in turn, lengthens the life of the paint job.

Second, primers help give the finished paint job a more. uniform appearance in terms of color and sheen, thereby making it more attractive. This is especially true when the surface being painted is porous or is uneven in porosity.

Third, some primers help prevent stains caused by water, rust, smoke, creosote, and other substances from coming through the paint from the surface and ruining its appearance. This is especially important with latex paints, which otherwise are vulnerable to stain bleed through. Others are more suitable for use on "severely staining woods," such as cedar and redwood, which contain tannins that can bleed through and discolor the paint. Whenever you use a primer, it is important to know if stain blocking is one of its capabilities, arid, if so, what types of stains will be blocked.

Closely allied with primers are specialty coatings known as sealers. Although sealers are similar to primers, they are designed to serve a different purpose. Some seal a porous surface, like weathered concrete or stucco, so the paint will develop a uniform sheen or gloss. Some also help protect the paint from the effects of efflorescence and alkalinity. Still other sealers, particularly those used on masonry like brick and stone, are designed to seal out moisture and remain unpainted.

When to Use Each Type

Priming is most important when painting a previously unpainted surface, though it has value even when repainting a sound, previously painted surface. In general, to achieve a high-quality paint job, we recommend using a primer or sealer when (1) painting new wood or any other surface that has never been painted before, (2) repainting a surface that is uneven or badly deteriorated, or (3) repainting a surface that has been stripped or worn down to the original surface material.

As with paints and other coatings, primers and sealers perform best when the substrate is prepared properly. Cracks, nail holes, and other surface imperfections should be filled and sanded smooth. Rusty surfaces should be wire-brushed. Weathered wood should be thoroughly sanded to remove all loose fibers. And, regardless of the application, the surface to be primed should be clean and free of all dust, dirt, grime, loose or flaking paint, and other contaminants before the primer is applied.

Types of Primers and Sealers

Once you determine that you can benefit from a primer or sealer, it's important to choose the right type of product for the application. …

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