Galvalume Steel Coil ( GL ) Home Products Galvanized (GI) & Galvalume (GL) Galvalume steel coil gets its name from being coated with a 55% aluminum-43% zinc alloy, also known as Galvalume. This special hot-dipped coating provides both sacrificial galvanic corrosion protection and a paintable surface ideal for architectural panels, roofing, and more.Excellent long-term corrosion