PAINTSQUARE BLOG

When writing a specification for protective coatings, too much can be just as bad as too little. What I mean is: Requiring a coating system with more capabilities than are really needed may not provide better performance, and it will almost certainly waste someone’s money.

We are all sometimes guilty of the attitude that if a little is good, more is probably better, or at least will guarantee that we get the minimum we need. Not so with coatings. While specifiers and manufacturers may be tempted to recommend the latest and greatest, highest-performance (and cost) materials, it’s often unnecessary—and at worst, a recipe for failure.

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In my opinion, constructability is an underappreciated facet of protective coatings specifying and application.

All of us should aim for a “Goldilocks” coating system: not too much, not too little, just right. And often that “just right” is based on application flexibility that will help ensure a successful in-place coating system.

Can It Be Done?

I started out my career over 40 years ago in the coatings-specifying department of a major global engineering-construction firm. But I spent most of my work decades on the contractor/applicator side of the business, so maybe that influences my perspective a bit. In my opinion, constructability is an underappreciated facet of protective coatings specifying and application.

The toughest locations for proper application are often just those spots where corrosion protection is needed most. They are the ones that will be the hardest (or nearly impossible) to get to and maintain later. Interiors of built-up steel members will trap dust, dirt and debris; will allow condensation to accumulate or rainwater to be trapped; and won’t see sunlight and ventilation that could dry out the moisture that’s creating a corrosion cell. These areas are coincidentally the toughest spots to clean, coat and inspect. If your system can be successfully applied with a rag, mitt or dauber, and tolerates an imperfectly cleaned surface, you are much more likely to have success, compared with one requiring a white metal blast and a plural-component spray gun.

Specifying a holiday-free paint system in a tank or vessel filled with unnecessary clips and internal stiffeners is much less likely to result in a successful lining than designing the interior to be free of all protuberances, right angles, sharp edges and projections. Just saying “I need this” in the specification doesn’t make it so, if the field conditions create impossible-to-apply locations. Any paint spec is only as good as the best efforts of a competent applicator can make it.

The Value of Compromise

It is worthwhile to remember that all protective coating properties are a compromise. If the ultimate chemical resistance is required, some ease of application and mechanical properties were sacrificed to achieve it. If great rigidity is needed, flexibility was lost. If your exposure is atmospheric, with minimal risk of aggressive chemical attack, then concentrating on surface tolerance, ease of application and gloss retention will result in a coating that performs the best for the longest period and therefore has the lowest installed cost.

Don’t be tempted to gild your lilies. Ultimately, the best paint system is the one that can be successfully applied, protects adequately, and costs the least in the long run.

ABOUT THE THE BLOGGER Robert Ikenberry Robert Ikenberry, PCS, has been in industrial painting and construction since 1975. Now semi-retired as the Safety Director and Project Manager for California Engineering Contractors, Robert stays busy rehabbing, retrofitting and painting bridges. His documentary on the 1927 Carquinez Bridge was the pilot for National Geographic’s Break it Down and an episode of MegaStructures. SEE ALL CONTENT FROM THIS CONTRIBUTOR