I know this is to late for your present windshield problem, but when the, repair is done as said before treat the entire area with POR-15. New metal needs to be treated with a conditioner prior to coating and rusty metal only requires wire bushing to get any loose flakes off. Guaranteed it will never rust again, you can't chip it with a hammer, impervious to water, acids and will never need re-coating as long as it is not in direct sun light but can be painted if desired. Be sure to wear rubber gloves, if you get it on your hands it will take a couple of weeks to wear off, also don't put the lid back on the can with any product around the lid as you will never get the lid back off, ask me how I know. PM me if you have any questions
Blessings; Keith
