What is it?
This defect appears as bare spots or coated-over rough spots on the surface of the coil. It may show up spotty or in clusters, and is similar to uncoated pinholes. Other names for this defect include pits, blemishes, or rough surface/spots. This defect is caused by a low snout, or hot bridle temperature, which allows the zinc vapor to condense and fall into the zinc bath or onto the strip.