Used outdoors copper sheet metal will gradually change through shades of brown to a black brown before developing a blue green patina, this may take up to 10 years but adds character to building features such as a roofing and cladding. Grade C106 copper, (Metal Sheets Ltd main stock), is a 99.9% pure general purpose copper, it is a phosphorus ... Twin Skin Metal Profiled Wall Cladding. 1.0 External Sheet 1.1 External Sheet Specification. External Sheet to be Coverworld 32W, 34W, 38W or 24W profile in Aluzinc coated steel substrate to 0.50mm nominal thickness, including alloy coating. Our perforated metal cladding panels may help you earn LEED credits. Architectural cladding is more than just a perforated metal façade. The system may be used to control air, heat and sunlight entering the interior, and reduce noise and wind — in addition to adjusting the degree of privacy and creating a beautiful and interesting design. Looking for construction and building materials? Sweets provides Sheet Metal Wall Cladding product directories to help you construct any building. Visit us today. Specification. Archclad ™ Express, 25 mm wall cladding and soffit lining. Product. Archclad ™ Express 25 mm is a clean, modern concealed- fix cladding systems with an attractive recess or express joint between panels. The express joint can be adjusted to suit the application and design of the project.