Visual corrosion beneath a paint film often called creep. Corrosion travels beneath the paint film and lifts the paint from the substrate. Severe cases can show as blistering, flaking,cracks and exposed rust.
Probable Causes: Application of paint to corroded substrate. Rust creep from areas of mechanical damage and missing primer coat. Can be found in areas of poordesign or access where inadequate preparation and coating thickness was applied. Could also be due to lack of maintenance.
Prevention: Use adequate coating specifications and maintenance procedures. Apply a suitably formulated primer.
Repair: Spot repair localised areas. Clean areas back to a sound substrate and apply suitable repair coating to manufacturer’s recommendations.