We've been asking a number of painters what they find as the biggest need homes have in the renovation arena and most will tell you that it is exterior painting. The reason that this service seems to be in such need is because homeowner's typically think of the exterior paint as something to make a home look good.
While the color and quality of a paint adds to the look and feel of a home's exterior, the primary purpose of paint and keeping up with painting needs is to provide a moisture barrier to protect the home's exterior structure. The durability of the paint determines coverage and depth of the coverage. A higher quality paint will last longer and may not need a second coat because the polymers in the paint have a stronger adherence to the surface as well as linking bond so that the strength of the paint coat is stronger. This deflects rain, debris and other outside elements better but also, increases the amount of time in between the need for another coat.
Most people ask, is Primer necessary? We thought it would be helpful to let you know what primer is for, when is necessary and when we think it's a waste so you can decide whether you need primer.
When you have uneven surfaces, minor imperfections or have porous surfaces, primer is the anchor to provide strong adhesion for the paint. These are situations in which you would want to use primer. Specific examples include:
Primer for Wood
New construction, whether a home, or interior or exterior build project requires primer because it is difficult for a paint topcoat to penetrate and adhere. Usually oil based primers were the only option for new wood but it could take up to 36 hours for the oil to be absorbed by the wood and for it to dry. Technological advances enabled major paint manufacturers to produce oil-based and latex-based products with quick drying adhesion. Duration by Sherwin Williams is one that we recommend. You want to make sure you have a quality manufacturers of paints where they have been tested by testing labs to ensure adhesion and durability to protects your home's exterior.
Primer for Masonry
Many masonry surfaces have high pH levels which can prevent adhesion if paint is applied directly. Overtime, paint will begin to loosen and peel. Using a quality masonry primer on the exterior, you are able to paint over a wide range of pH levels and reduce the loss of adhesion and peeling over time. Another issue you may have when painting over masonry is efflorescence. These are harsh looking crystalline deposits usually white or yellowish that form right on the masonry surface marring the facade. Quality masonry primers resist efflorescence and keep it from forming.
Primer for Stain-Blocking
Often in exterior painting, there are times when you are painting over a darker color with a lighter color paint. Or you are painting a chimney or covering other smoke or fire produced stains that may bleed through a topcoat of paint. Or for an interior paint job, painting over markers, grease markers, or other oil based stain, this is when a high quality primer is needed.
For your exterior paint project, a good rule of thumb is, when your project is a surface that has previously been painted, you probably don't need primer. If your concern is covering a certain color paint, the paint and primer in one do an excellent job of covering old paint.