Flash rusting can present a significant problem when preparing metal structures for coating and painting, as it forms very quickly on steel that has been newly blasted, especially when sandblasting or other conventional dry blasting are methods are used. If not checked and controlled, flash rusting can fatally undermine the integrity of steel marine structures, boats, ships and machinery and cause protective coatings to fail.
Flash rust is caused by salt deposits on the surface of newly-blasted metal (a constant hazard in marine environments) which, when mixed with water, cause corrosion cells to form. The problem is exacerbated and accelerated in humid environments.
In dry blasting, the sandblasting media is not rinsed off leaving soluble salts and other contaminants on the surface to a certain degree.