The farmhouse we are rehabing has a tin roof on it that was installed in 1960. The whole roof has a lovely rusty patina on it and I really, really want to keep the look. However, though it is not leaking now, it is developing pits in the surface of the rust so it is just a matter of time. Does anyone know of any product we can use to stop the rust and seal the roof without covering that beatiful rust patina? I have looked at Cool Seal (don't like the look, we put it on the roof of the mobile home we are living in while redoing the house) and a product called Elasto something but, both of these would completely change the color of the roof. Is there something transparent with a matte finish out there that will do what I want? Help!!!