[frank long island]

all metal is a very good product for what its intended to be used for you cant expect to fill a rot hole and have it work as water is going to attack it from the back I would clean the rusted area and use a sealer/rust converter then apply your filler the key is to use a product that wont attract moisture they also make a short strand fiberglass spreads like filler I use this over my welded in patches before body filler