Surface preparation and application requirements for coatings over structural steel are often overlooked in project specifications. While this is not critical for many applications because the steel is covered by other finishes such as gypsum or pre-finished metal panels, it can be problematic for architectural exposed finishes or components requiring fire protective coatings.
The typical standard surface preparation at most steel fabricators is to blow away loose material with compressed air, wipe with solvent, and paint away. Mill scale, weld slag/splatter, oils, and other items are often painted over when the steel is primed. Even if the finish coating is properly applied by a professional painter, coating performance can be greatly diminished by the primer’s lack of adhesion to the steel substrate. Periodic surface preparation and coating application observations by a third party is a good way to protect all parties involved, ensure a quality finished product, and save an owner a great deal of money in premature maintenance costs down the road.