Here are some interesting photos from a failure analysis that I conducted at a car wash. On the concrete walls, blisters were widespread and concentrated in areas with the greatest exposure to water. After the blisters of the topcoat were removed, the exposed block filler was found to be soft and moist. Further investigation determined that the contractor had applied an alkyd topcoat over an acrylic block filler. Moisture had passed through the alkyd topcoat and was easily absorbed by the acrylic block filler. As the moisture tried to escape from the saturated block filler, it became water vapor. Upon expansion of the vapor, widespread blisters formed under the alkyd topcoat.
This is a good reminder that acrylic block fillers and alkyd topcoats are not suitable for use in wet environments. The technology built into today’s coatings has come a LONG way since I started in the coatings industry. However, a good coating in the wrong environment is a ticket to an early failure. When coating a car wash, stick to epoxy block fillers and topcoats with a proven history in wet environments. Car washes aren’t a place for experimentation or trying to save a few bucks. When choosing coatings for a job, be sure you consider the specific demands that the coatings will be exposed to. A few dollars per gallon and some time spent on proper planning could have prevented this failure.
For coatings professionals, these are interesting photos. For the contractor and the building owner, these are photos of an expensive failure that was avoidable. Careful consideration of the capabilities of today’s coatings will result in years of protection in the most demanding environments.
*Photos used with permission