March 25th, 2018 Should You Always Use Primer?
Not necessarily. It actually depends on several factors. In short, however, the two main reasons for using primer are (1) to lock in the previously painted surface to make sure no oils or stains (e.g. water) bleed through, and (2) to create proper adhesion for the new coating you will be applying.
Applying The Right Kind Of Primer
The tricky part about primers is that there is no one size fits all. In fact, it is quite the opposite. Each primer is designed to address specific surface needs and conditions. If the wrong primer is applied, you can almost guarantee that your paint job will not last. Perhaps the more appropriate question is not whether you should apply primer, but which one is the right one for my project. But, that’s what we are here for. Below, we will discuss and properly match primers to each specific surface and situation.
Raw/New Drywall & Raw Wood
There are no exceptions here; any newly-installed drywall must be fully primed. Raw drywall must be sealed as is very porous. Unlike finish paint, drywall primers have more resins (fillers and binders) and fewer pigments resulting into a thicker-body mixture, which fills in pores beautifully. Also, since more resins reduce absorption rate, one coat of primer will get the job done. If you were to use finish paint instead of primer, you can still reach the same results. But you will need several coats instead of just one primer coat. At this point it becomes cost ineffective as more coats require more labor, and finish paint is more expensive than primer. In addition, primers are chemically designed to create “tooth” making it an ideal surface for finish paint to adhere to. That’s why primer feels rougher to the touch. Lastly, a good primer will help reduce visible imperfections.
For the same reason noted above, any drywall patch work larger than 5″ and any raw wood also should be primed.
Painting Over Oil-base Paint Or Highly Reflective (Shiny) Paint
If your current surface has oil-base paint, and you want to change it to a latex (water base) paint, you must first apply a coat of oil base primer. The oil-base priming coat will lock-in the previously painted surface. Plus, it will give you the necessary adhesive property that your new water base paint needs in order to stick to your surface permanently. This is a critical step to ensure the longevity of your new paint job.
That very smooth surface that we all love about a highly reflective, or shiny, paint is the very reason why you need to prime with an oil base product before applying your new paint. Regular paint will not stick to a shiny surface as it lacks the adhesive properties that an oil base primer has.
In short, oil base and shiny paint must always be primed with an oil base product. And only then can you apply latex paint over it. Just remember, you fight fire with fire, and you fight oil base paint with oil base primer.
Painting Over Deep/Dark Base Colors
In this case, priming will greatly be your best (and cheapest) bet. If you have a deep/dark base color and want to change it to something lighter, priming will provide you with a clean, new canvas. Simply put: tabula rasa, a blank slate. You might still see a bit of the old color bleed through, but it won’t be significant enough that it would alter the appearance of the new color. Lastly, your project will be more cost effective since primers are significantly less expensive than finish paint.
Water Stains, Small Mold And Mildew Stains, And Odors
Whether you are dealing with a water leak, relatively small mold and mildew, or other stains, spot priming with an oil base product will unquestionably do the trick. Of course, the source of the problem itself must be addressed before you tackle the stain issue. Otherwise, you will be right back where you started.
When it comes to odors, the biggest odor-related issues we have encountered were caused by heavy smoking inside a house. Despite the source of the odor, once again, any oil base primer will more or less get rid of the smell.
Surfaces such as metals, stainless steel, galvanized, etc. should always and only be primed with primers that are specific to each metal. In other words, if you want to paint over a stainless steel surface, you must use a stainless steel primer, galvanized surface primed with a galvanize primer, and so for.
Tinting the primer to the color you want is always a great idea. It will help with coverage and you also get a glimpse of the color you chose.
We don’t recommend reducing primers.
Stains should not come through, unless the primer was not applied correctly, or the source of the stain was not fixed.
Raw drywall and woods are like sponges in terms of absorption, which is why primer is always a must.
Jason Bertoniere, Inc. believes that your paint job is as good as the coating behind it.
Existing oil base and shiny paint must always be primed with an oil base primer.
Primers help tops coats adhere better.