[Hugo Junkers has entered the chat]
I don’t know about galvanized and I think rusty can be ruled out, but Junkers built his first models in the mid-1910s from steel.
Alfred Wilm had already invented duralumin a couple of years ago, but at the time it still had undesirable characteristics like flaking when worked in sheet metal form. Also, Junkers already had established a company that made boilers and had workers with a lot of experience in welding thin steel.
