Separate surface corrosion from failure underneath
A rust mark below a hinge, bracket or gate fitting can come from the fastener, the fitting or water trapped behind it. Photograph the whole assembly, check movement and note whether staining returns after cleaning. Painting over corrosion without preparation can hide continued loss of material. Replacement hardware must suit exterior exposure and the material it connects to; incompatible metals can accelerate deterioration. Timber around screws may also be softened or split. Keep a removed part until dimensions and handing are recorded. Significant railings, gates or historic metalwork may need a specialist and consent rather than a general replacement. The repair choice follows condition, not simply the colour of the stain.

