Cor-ten Steel is a type of steel that oxidizes naturally over time, giving it an orange-brown color and a rough texture. It has a very high tensile strength, and in spite of its rusted appearance it is actually more resistant to damaging corrosion than standard forms of carbon steel. It has been used by many contemporary sculptors and architects. United States Steel Corporation says "COR-TEN? is a registered trademark of United States Steel Corporation and can only be used for products produced by United States Steel Corporation or its licensees. COR-TEN? Steel has proven to be an excellent product for bridges, primary structural framing and sculpture."Examples: Claes Oldenburg (American, born Sweden, 1929-) and Coosje van Bruggen (American, born Netherlands, 1942-), Clothespin, 1976, Cor-ten and stainless steels, 45 feet x 12 feet 3 inches x 4 feet 6 inches (13.7 x 3.7 x 1.4 m), Centre Square Plaza, Fifteenth and Market streets, Philadelphia. See Pop Art. Richard Serra (American, 1939-), Five Plates, Two Poles, 1971, Cor-ten steel, 96 x 276 x 216 inches, Walker Art Center, Minneapolis, MN. See Minimalism.