Why Industrial Coatings Fail, and How to Prevent It
When an industrial coating fails early, the first suspect is usually the product. It is rarely the product. In the failures we are asked to look at, the cause almost always sits in one of four places: the surface underneath, the conditions on the day, the thickness applied, or a system that was never right for the exposure in the first place.
1. The Surface Was Not Prepared Properly
Coatings fail at the interface, where they meet the steel or concrete. Oil, salts, dust, mill scale, rust or a weak old coating left on the surface all give the new coating something other than the substrate to grip.
On steel, the fix is blasting to the cleanliness and profile the specification calls for. On concrete it is grinding or shot blasting to remove laitance and open the surface. Preparation is the slowest and least visible part of the job, which is exactly why it gets cut when schedules slip.
2. The Conditions Were Wrong
Every coating has a window. Too cold and it will not cure. Too humid, or a surface too close to the dew point, and moisture condenses on the steel before the coating goes on. The coating can look perfect when the crew leaves and release weeks later.
Measuring air temperature, surface temperature, humidity and dew point takes a few minutes. Not measuring them is how good material ends up on the floor.
3. The Thickness Was Wrong
Too thin and the coating cannot protect what it covers. Edges, welds, corners and bolt heads are where thin spots hide, because coatings pull away from sharp edges as they cure. Too thick and some systems crack or trap solvent.
Wet film readings during application and dry film readings after it catch both problems while they are still cheap to fix.
4. The System Did Not Fit the Exposure
A coating that performs beautifully on an exterior wall can fail fast under immersion. A floor coating rated for traffic can soften under a chemical it was never tested against. A topcoat that holds up indoors can chalk and fade in Columbia Basin sun.
The specification has to start with what the surface faces: chemicals, temperature, water, traffic, ultraviolet. The product comes after that, never before.
What the Failures Look Like
- Peeling in sheets: usually preparation or moisture.
- Blistering: moisture or solvent trapped under the film, or immersion the system was not built for.
- Rust spotting through the coating: thin film at edges and welds, or pinholes.
- Chalking and fading: a topcoat that was not UV stable.
- Cracking: film applied too thick, or a rigid coating on a surface that moves.
How to Prevent It
Specify against the real exposure. Prepare the surface to the standard the specification demands, and do not let the schedule shorten it. Measure conditions before application, thickness during and after it, and write the results down. That last step is the reason we keep a NACE Level III coating inspector on our own staff.
Industrial Coating Failure Analysis
If a coating on your site has already failed, the useful question is why, before anything gets recoated. Recoating over the same cause gets you the same failure. We look at the failure pattern, the substrate and the exposure first, then specify the repair. Call (509) 579-0444 or request a quote to have a failed coating looked at.
Frequently Asked Questions
Surface preparation. Contamination, rust, mill scale or a weak old coating left under the new one is behind most early failures.
Peeling in sheets usually points to poor surface preparation or moisture coming through the substrate, especially on concrete.
Not safely. Recoating over the cause of the failure repeats it. The cause has to be found and the failed coating removed first.