What is it?
This is primarily a galvanize defect. It looks like colored stains on the steel’s surface, usually in streaks. The color of the stain varies depending on the chemical treatment vendor, but is usually yellow, gold, green, red, or brown in color. This defect is also known as stain or streaks. It is usually caused by mechanical failures at a chemical treatment’s wiping section (plugged blow-off lines or cut wiper-rolls).