Cor-Ten is a material of great scenic effect and extraordinary elegance. In recent years, it has become a very popular material for windows and doors, both for restoration and for new buildings. Cor-Ten is a natural, living material that takes on different and unique shades over time and through exposure to the elements. The natural oxidation process can also be controlled chemically, with procedures that reduce natural “bleeding”. In order to contain these phenomena, however, it is advisable to plan periodic treatments with applications of suitable waxes or oils. The corners of the frames are suitably welded, and the welding mark can be left natural or ground flat.