Well maintained iron products have high corrosion resistance and longevity as demonstrated by early 18th century iron street furniture that can still be seen in many provincial towns and cities throughout Europe.
Unlike steel, unprotected iron can remain exposed to the elements for several years without undue effect on the products structural integrity. However, if the protective coatings are allowed to deteriorate, oxidation will occur and attempt to spread over the surface and will lift the paint or coating surrounding the damaged area. From a cosmetic point of view, it is therefore best to remove any oxidation with a wire brush and re-paint the damaged area to prevent the oxidation spreading. (Note: oxidation does not constitute a health and safety hazard).