Poor coating adhesion from inadequate surface preparation is the primary reason for most coating delamination issues, says Chris Sullivan of ChemSystems Inc., a manufacturer of color and cement-based admixtures.
Chris Sullivan Poor coating adhesion from inadequate surface preparation is the primary reason for most coating delamination issues, says Chris Sullivan of ChemSystems Inc., a manufacturer of color and cement-based admixtures.

Time is rarely a contractor’s friend, but it’s particularly hostile to sealant/coating applicators.

As the last or near last step, you’re pressured to make up time by placing the product while the concrete’s too wet — and thus the high failure rate due to moisture. To keep costs down, architects and general contractors resist specifying moisture mitigation systems; even if allowed, the products need a seven-to-14-day or more waiting period for the concrete to cure and dry. And then crews working for other contractors walk on the cleaned and prepped floors and damage fresh applications.

Given all this, it’s amazing that applications don’t prematurely fail more often.

“Virtually any design-specification-construction problem reveals a combination of influencing factors,” says Ken Hover, a Cornell University Civil and Environmental Engineering Department professor who’s investigated failures for four decades. “The right product, installed in almost but not quite the right way, has a good chance of success, unless the substrate is, likewise, almost, but not quite as anticipated, or the exposure is likewise not quite as planned. Only a few cases have one, and only one, cause.”

Anatomy of an investigation

Hover approaches an investigation by answering four questions:

  • What was this coating supposed to do, and was the appropriate product chosen to accomplish that goal? Sometimes, no one ever clearly defined the coating’s purpose. “Mom may have said ‘put on your coat,’ but it would be a different coat for rain than for snow,” Hover says.
  • Has the coating torn, leaked, worn away, dissolved, or disintegrated? If so, this indicates failure of the coating, which could be related to the coating material and to the application or selection for a given environment or exposure.
  • Is the coating still attached, bonded, adhered, or glued to the substrate? If not, this indicates a failure at the coating/substrate interface, which could be related to surface preparation or application.
  • Has the substrate delaminated or otherwise come apart or disintegrated below the interface? If so, this indicates a failure in the substrate. This could be independent of the coating, and may have more to do with substrate condition or whatever’s penetrating into the substrate.

Sometimes this is all that’s needed to diagnose the problem and recommend repair or replacement. Other times, additional chemical or physical testing is necessary.

Let’s say an investigation determines failure wasn’t due to substrate issues or another contractor earlier in the process. Does the coating contractor have to do whatever it takes to make the customer whole?

“That depends entirely on the specification and the terms of the contract or purchase order,” Hover says. “Did the customer's schedule accelerate the work or force premature application? Did the contractor agree to a performance criteria (no leak, no rust for XX years), or did the contractor agree to putting down whatever product the client wanted according to the manufacturer’s instructions?

“If the contractor used what the client wanted and applied it in the specified manner, there’s a good argument that the client owns the problem. But if the contractor promised some aspect of performance, then the responsibility can shift toward the contractor.”

There are relatively easy, lawyer-free ways to make an investigation less burdensome and more likely to end favorably.