7. Coating Failures

7.4 Types of Failures

4. Adhesion Related Failures

  1. Blistering

  2. Flaking


(A) Blistering


Formation of large broken or unbroken bubbles or hollow dome shapes on the surface of a painted substrate.




The following are the major causes leading to blistering:

  • Application of paints over oil contaminated surface. Oils and waxes on the substrate do not allow good adhesion.

  • Solvent retention: Solvents retained due to incomplete release increase absorption of moisture and water causing loss in adhesion and blister formation.

  • Applying an organic top coat over a porous inorganic coat on a warm substrate. Blisters are formed and broken and leave the substrate surface exposed to environment.

  • If excessive cathodic protection is applied, the hydrogen formed under the coating pushes the coating because of increased vapor presence.

  • Soluble salts formed as a result of inadequate rinsing or presence of prior corrosion sites create active sites for the formation of blisters.

  • Application of high performance coating over an incompatible shop primer (a special primer applied on steel after it has been cleaned in a centrifugal machine) may lead to blister formation on the substrate.



  • The damaged areas should be stripped back to the base metal and the coating re-applied on the damaged areas.

  • If the damage is extensive, it may be necessary to remove the entire coating, clean the substrate and re-apply the entire coating.