What is it?

Primarily a zinc-related defect, this defect can appear in non-linear patterns, and can come and go randomly throughout the coil. This defect always has a mirror finish and happens close to the mill edge. It is also known as condensation rust or white stain. This defect occurs during the transport of the coil, where the coil gets wet in transit. The mirror finish of the defect confirms the intrusion of moisture from the sidewall. Because the moisture usually collects at the bottom, the lower portions of coils affected by this defect are usually worse in their severity.

White Rust