Stainless steel gets the "stainless" portion of its name from its chromium oxide coating that resists staining, pitting and rusting. But although it holds up better than other metals, stainless steel is not impervious to rust. Time and certain environmental conditions like salt air will slowly erode stainless steel's protective coating. When the chloride in the aerosolized salt in salt air lands on the surface of the stainless steel, it breaks down the chromium oxide. To keep that from happening, you must put a protective layer over the chromium oxide to keep the salt off its surface.
Things You'll Need
Sand away any rust present on the stainless steel with a block of very fine-grit sandpaper.
Wipe the stainless steel's entire surface clean with a soft cloth moistened with denatured alcohol.
Apply a corrosion-resistant coating to the stainless steel to protect it from salt air. Clear coatings and paints specially designed for stainless steel are available online or at certain hardware stores. Depending on the manufacturer, they may be applied with a spray can, spray gun, brush, roller or special applicator. Follow the manufacturer's instructions for application. The clear coat will take just about as long to dry as any other coat of paint -- one to two hours to dry to the touch, overnight to cure -- but drying times vary depending on the type of paint and the humidity in the air.
Refresh the coating periodically as required. .The amount of time between coatings varies widely with the type of coating, the weather conditions the stainless steel is exposed to and the amount of physical wear on its surface. Hand rails will need coating more often than flagpoles, for instance. Stainless steel in coastal locations will need more frequent renewal.