Ask The Painter: When do I need Primer?

(“To prime or not to prime?”) 

There are some newer products on the market that are making a big deal out of the fact that they have the primer “built-in” and can therefore cover better.  But is “primer” built in to the paint really necessary?  And how effective at “priming” are the so-call self-priming paints?  How do you know when primer is truly needed?  In many cases, “primer and paint all in one” may be more about marketing than painting. 

Generally speaking, “primer” (and there are many kinds) is used to solve a specific problem, or meet a specific need that paint alone does not address well (if at all).  For example, “stain blocking” primers are used to seal-in watermarks before painting, while “high-build” or “conditioning” primers are used to seal the rough or porous surfaces of new drywall.  Other specialty primers will “lock down” the edges of checked (“alligator skin”) or weather-cracked paint, lock-up chalky residue from old paint breaking down (even a strong power-washing will not eliminate this), or bond to metal.  Just because a paint has “primer” built-in does not mean that the primer will solve your specific problem. 

In some cases, painters may use a primer coat to “neutralize” an existing color so that it won’t influence the new top coat color, or to create a “foundation” for a dark or vivid color (navy blues, reds, etc).  In cases such as these, primer may simply be used as a substitute for paint because it is cheaper than premium-grade top coats.  In other cases, the need for a second coat (whether primer or paint) may be completely eliminated by choosing a premium grade paint with better “hide” properties.  

In cases where creating adhesion for the top-coat is critical — new wood, for example — 100% full-strength primer may be a better choice than a “self-priming” paint.  This is not to say that the so-called self-priming paints are without merit.  There are many self-priming “specialty” paints that do an outstanding job of meeting a specific need (adhering to metal, for instance).  And there are many applications (painting gutters/downspouts or garage doors, for example)where having primer incorporated into the paint formula  can make a big difference in the life span of the top coat. 

So that brings us back to the paints with the primer “built-in” mentioned at the beginning of this article.  The question to ask is this: What problem is being solved by using a self-priming paint?  Is a self-priming paint really necessary?  Or necessarily adequate?  When faced with a situation requiring two coat coverage, is a coat of primer and one coat of paint better or worse than two coats of paint?  

As with so many things with painting, the answer to these types of questions is often “it depends”.  The desired performance characteristics of the top-coat and the surface over which it is being applied are the two major factors to consider when choosing the proper approach, and therefore when answering the question of whether “to prime or not to prime?”.  Professional Painting Estimators or properly trained clerks at paint stores are great resources to help you answer this question.

Copyright 2009 Jeff Stec