Which of the following is an example of a coating defect?

A coating defect refers to issues that arise within or on the surface of a protective coating applied to surfaces, typically to prevent corrosion or damage. Holidays and blisters are specific types of coating defects characterized by the presence of discontinuities, such as voids or bubbles in the coating material. These defects can lead to compromised protection of the substrate, allowing moisture or corrosive substances to penetrate, which ultimately can cause further deterioration.

Cracks, while they can occur in a coating, are not typically categorized under protective coating defects in the same way holidays and blisters are. Dents signify physical damage to the substrate rather than a failure in the coating layer. Rust is a result of corrosion of the substrate material, indicating that the coating may have failed to provide adequate protection, but it itself is not a defect within the coating.

Thus, holidays and blisters are clear examples of defects found in the coating that compromise its integrity, making this the correct choice for identifying a coating defect specifically.