"Paint Grip” steel is mill phosphatized or galvannealed. Galvanneal steel is, as its name implies, annealed. This annealing softens the steel, making it more prone to dings and dents.  Mill phosphatized steel has a zinc phosphate coating. Zinc phosphate is considered dangerous to aquatic life and special handling is required at the mill to prevent its release into the environment.  Both annealing and phosphatizing processes promote paint adhesion by damaging the original hot dip galvanized coating. This means that once you specify or choose “paint grip” you have no choice but to paint it. “Paint grip” steels are also rougher than standard hot dip galvanized steel so additional lubricants are required in the spiral forming process, which in turn will require additional cleaning in the field.