Definition - What does Bubbling mean?
This is the formation of pimples or blisters on the coated or painted surface of a substrate. It can be caused by excessive heat under the paint or the application of layers of coating without giving them enugh time to dry thoroughly. Bubbling is the foundation of cracks in paints, hence a clear indication that the painting or the coating needs maintenance. It is a clear indication the corrosion might be taking place and waiting for long might lead to failure in the material structure.
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Corrosionpedia explains Bubbling
Bubbling is common in aircrafts since air tends to get under the coating or painting; another cause of bubbling would be corrosion under a paint or coating and material contamination. In the case that bubbling occurs on the surface of the substrate, chances are that a corrosive environment has been created.
This is spotted in areas where moisture and air can easily penetrate, especially in cracks, seams and rivets. It occurs where there is an adequate environment for corrosion and also when the part is in motion. Failure is achieved when the bubbling increases and corrosion is spread.
Therefore, bubbling assists in identifying whether the surface finishing needs repair and also identifying hidden corrosion. Stripping off the substrate coating will show the level of corrosion and extent of damage to the material. Corrosion prevention is partially achieved by controlling the rate of corrosion through repainting and other coating maintenance.