This is a glass guy’s nightmare. If you have a lot of rust, your glass guy/gal may tell you that you need to take your car to a body shop. Why? To sand down the rust. Our primer will not stick to rust. If the primer does not stick to rust, your windshield will not stick to the rust and therefore, you have a BIG problem.
Glass guys do not charge to take care of small rust problems, but this kind of thing takes hours and tools that most glass people just don’t have.
Rust occurs when there are leaks in your windshield. If you have leaks, please consult the last person who put in your windshield. This can happen after you buy a new car as well. Can you test for it? Sure! Take your care to a car wash and spray down your windshield. Sit inside. Are their leaks? If so, address them sooner than later!