Galvanized Roof Rust

The fiber acts a bit like a tire plug in the old nail holes and prevents leaks and it sticks well.

Galvanized roof rust.

But galvanized metal which exhibits a shiny adherent but rust colored stain is not truly rusting. Left untreated white rust corrodes the zinc and the metal underneath begins to rust exhibiting the more traditional brownish red color. Rust is the reaction of oxygen moisture and metal that results in reddish brown blotches. I like the fiber in the aluminized roof coat as well as in the black nearly tar roof coat.

Galvanized metal roofs are coated with a layer of zinc that inhibits rust. Rust corrodes metal and if left untreated it can cause. Galvanized metal is coated with a layer of zinc to protect the iron or steel underneath. If the item is exposed to continually wet conditions the zinc develops a film known as white rust.

Unfortunately over time this coating can fail leading to minor rust outbreaks. I have used both regular paint and roof coat on old metal roofing with pretty good results. It is not simply a cosmetic problem however. The roofs i have done have lasted a minimum of 20 years now.