Ace Metal Building

The substrate is the rust-inhibitor coating that is covering the steel but under the paint. A Galvalume substrate uses a combination of aluminum and zinc to protect against rust, whereas a Galvanized substrate uses zinc. Galvalume may begin to show rust around the edges of the panel before a galvanized substrate, but the rust should stop when it comes in contact with the aluminum in substrate. A galvanized substrate will take a several years longer to show edge rust, but once the rust starts it could continue to corrode the whole panel.