Primers and sealers
help the paint adhere to the surface and make the surface more accepting of a topcoat. Primers and sealers also prevent stains and tannins from bleeding through the paint. These stain-blocking primers are particularly useful on “staining” woods such as redwood, cedar, and mahogany. They also give a more uniform appearance to the finished paint job.
Sealers are similar to primers but are primarily used on new wood or masonry surfaces that have varying degrees of porosity. Sealers keep the topcoat from being absorbed unevenly. Most manufacturers offer a product that performs as both primer and sealer, so that you get the advantages of sealing and adhesion at the same time.
Always us a primer on new wood or any other surface that has never been painted. It is also necessary to use primer/sealer when repainting a surface that is uneven or badly deteriorated. A surface that has been stripped or is worn down to the original material must be cleaned and sanded and the primed.
To ensure an even gloss on a surface, even out the surface porosity by applying a primer, especially when using a primer will mean fewer finish coats, and a better end result. Also, primers tend to be less expensive than finish coats, so by using a first-coat primer and one finish-paint coat, you may save money over using two finish coats.
USING DEEP-BASED PRIMERS
If you are going to use a dark color on your exterior, use a deep-tone base primer. It is a mistake to believe that additional coats of the finish paint will provide the same result as an initial coat of primer. Some colors are very clean and transparent, which means that you can put ten coats of paint on and still see through them to some degree if you did not use the correct primer.
For some colors, a different-toned primer is actually the way that the final color is”built”. Having to use a different-toned primer has nothing to do with poor paint quality, which is usually blamed. These colors are designed to use a specifically formulated base color that actually builds the color. In many cases, this base color is not the same as the final color. Do not be shocked if you want red and the manufacturer recommends using a primer the color of bubble gum. Always follow the manufacturer’s directions for true color.