Definition - What does Pinpoint Rusting mean?
Pinpoint rusting refers to a type of corrosion that results in the formation of tiny, dispersed spots of rust across a metal surface. Pinpoint rusting typically occurs where pinholes or holidays are present in a coating.
Corrosionpedia explains Pinpoint Rusting
Pinholes are formed due to an improper solvent balance when the coating dries rapidly, or due to inaccurate spraying during the application of the coating.
Holidays are formed due to the inaccurate application of a coating, which results in some areas of the metal surface remaining uncoated. Such locations are usually located at or near tight angled corners, rivets and longitudinal pipe lengths.