The Importance of Primer
Many of us get in such a hurry to paint and see how our fresh new walls will look that we skip the most crucial step-applying primer before you paint. Primer is an absolute necessity when you are painting a surface for the first time, and even when you are re-painting a surface, a coat of good primer can make all the difference in how your finished wall looks. Most higher-end brands of paint have their own brand-name primer, or Kilz makes a good basic primer that works well for repainting walls as it covers stains and marks fairly well. Primer is generally pretty quick-drying, and within an hour from when you start, your surface will likely be dry and ready for the paint color coat. The purpose of primer is to put a layer between your surface and your new paint; the primer is designed to adhere to surfaces and form a type of binding layer, enabling it to better accept paint. As my husband-the painter-often says, "Paint doesn't stick to wood, paint sticks to primer." Meaning, that especially if you are planning on painting a new wooden deck or fence, you are literally spinning your wheels if you apply paint without a first coat of primer. In less than a year your paint will be peeling off in strips because, well, because paint sticks to primer, not wood!!
Extend the Life of Your Paint
If you are ever tempted to skip the primer step, just remember that primer makes your paint more durable, allows it to stick to your surface better, and even helps bring out the true color of your paint. If you've ever chosen one of the little color swatches from the paint store, and painted without priming, you may have been terribly disappointed to find that the color looked nothing like the one you chose. Also, if you are planning to paint a lighter color over a dark color, primer is not just highly recommended, it is critical. If you are painting plaster, and skip the primer, you will be very dismayed to find that the plaster will simply eat right through your carefully applied paint. Even though paint has come a long way in the past twenty years or so, it still requires the critical step of applying primer before you paint. Using primer-which costs much less than high-grade paint, also allows you to use much less of the expensive paint in order to get a perfect finish.
Tinting Your Primer and Exterior Priming
You can go the extra step and have your primer tinted the same color as your paint, which will give you a beautifully finished wall. If you choose to add this extra step, your walls will not fade nearly as quickly as if you use plain, white primer, and you will get many more years of use before you have to re-paint. Walls which get large amounts of sunlight will really benefit from having your primer tinted. Failing to apply a primer can actually injure outdoor wood surfaces by allowing water to leech into the grain every time the surface is exposed to the elements. If you skip applying primer when painting outdoors, you are creating a devastating condition which is highly conducive to mold, mildew and warping. Many people mistakenly believe that outdoor paints are waterproof, however in reality they are not, and require the use of a primer.
Always Remove Mold and Mildew First
The only thing that primer is decidedly not good for is to seal in mold and mildew-always thoroughly clean your surface of mold or mildew prior to applying primer; it's a good idea to spray with a mild bleach solution after cleaning and before applying primer. Allow the bleach solution to dry thoroughly before applying primer, then apply 1-2 coats of primer, and finally your color paint coat.