Sounds to me like you should be using painted faux finishes. I would not attempt to put on a real rust finish and then top coat it. The only weather vane I made was made with stainless steel, copper, and brass. No steel. No paint. It was an owl weather vane I made for UNC at Chapel Hill.
One suggestion. Make sure the vane is installed perfectly level. Otherwise, it's not going to work correctly.
Sounds to me like you should
Sounds to me like you should be using painted faux finishes. I would not attempt to put on a real rust finish and then top coat it. The only weather vane I made was made with stainless steel, copper, and brass. No steel. No paint. It was an owl weather vane I made for UNC at Chapel Hill.
One suggestion. Make sure the vane is installed perfectly level. Otherwise, it's not going to work correctly.