Coatings degrade; what indicators would you look for?

• A. Chalky deposits indicate aging.
• B. Peeling, cracking, blistering, chalking; inspect adhesion and corrosion under coatings with removal.
• C. Coatings never degrade.
• D. Coatings degrade due to UV exposure.

Answer: (B)

When evaluating coating condition, focus on signs that the protective barrier is failing and that there may be damage beneath the surface. The clearest indicators are peeling, cracking, blistering, and chalking.

Peeling shows the coating has lost adhesion to the substrate, meaning a portion can lift away and no longer provide a continuous barrier. Cracking reveals stress, poor film formation, or age-related brittleness, which creates pathways for moisture and ions to reach the metal. Blistering indicates moisture or gas trapped under the coating, pushing the coating up and creating voids that can lead to corrosion beneath. Chalky deposits point to binder degradation and weathering at the surface; they signal the coating is breaking down and losing its protective integrity.

When you observe these signs, you should remove the coating in the affected area to inspect adhesion directly and to check for corrosion or other damage under the coating. If corrosion is found beneath the coating, you’ll need to address the substrate, reprepare the surface, and reapply a proper coating system to restore protection.

UV exposure can contribute to degradation, but it’s not the sole cause and doesn’t by itself indicate the full extent of coating failure.