Description: Dome shaped projections or blisters in the dry paint film through local loss of adhesion from the steel substrate.
Probable Causes: Non-osmotic blistering associated with electroendosmosis, cathodic disbonding,thermal gradients related to cold wall effects and compressive stress. Where electroendosmosis is involded, the blistering is often seen as a circular pattern of blisters around a coating defect where the substrate is exposed.
Prevention: Ensure correct surface preparation and application.Apply a suitable coating system after considering the possibility of the different blister mechanisms in the particular environment.
Repair: Depending upon size and type of blistering, remove blistered areas or entire coating system and repair or fully recoat.