Coating Failure Analysis and Remediation Flashcards

What is the most common root cause of coating delamination from a steel substrate?

Answer: Inadequate surface preparation

Inadequate surface preparation is the leading cause of coating failures because contaminants and poor anchor profile prevent proper adhesion.

Which type of coating failure is characterized by dome-shaped hollow projections rising from the coating surface?

Answer: Blistering

Blistering appears as dome-shaped hollow projections caused by moisture, soluble salts, or osmotic pressure beneath the coating film.

Which coating defect results from UV degradation of the organic binder, leaving loose pigment particles on the surface?

Answer: Chalking

Chalking is caused by UV degradation of the binder, which releases pigment particles that remain loosely on the surface and can be wiped away.

Which condition most commonly causes pinholes (holidays) to form in an applied coating?

Answer: Solvent entrapment during curing

Solvent entrapment during curing creates small voids or pinholes as trapped solvents escape through the drying film, leaving holiday defects.

What is the term for a coating failure in which paint separates from the substrate or underlying coat in large continuous sheets?

Answer: Delamination

Delamination refers to the separation of a coating film in large sheets from the substrate or between coats, often exposing bare metal.

Which standardized test method is used to evaluate coating adhesion by making a crosshatch cut and applying tape per ASTM D3359?

Answer: Cross-cut adhesion test

ASTM D3359 cross-cut adhesion test involves scribing a grid pattern through the film, applying tape, and rating how much coating is removed to assess adhesion.

Alligatoring (crocodile cracking) of a coating surface is typically caused by which condition?

Answer: Application of a hard topcoat over a soft, incompletely cured primer

Alligatoring occurs when a rigid topcoat is applied over a softer, incompletely cured undercoat that continues to move, causing the hard film to crack in a pattern resembling alligator skin.