Outdoor
Stainless steel outdoor lighting, fences, masonry and thresholds are electro-polished to prevent those typical brown rust specks. Staircases and tread boards are electro-polished for the same reason. For outdoor architecture, electro-polishing stainless steel is essentially indispensable.
Studies show that (sulphurous) acid rain is the primary culprit for staining of stainless steel. Untreated stainless steel types both AISI304 and AISI316 are easily stained as well in a rural, as in a maritime, as in industrial environment. Electro-polishing prevents such, and even repairs slightly stained surfaces.