Over ground galvanizing

The dark shiny area is an indication of the galvanized coating having been completely removed during the grinding process.  You will notice that there is an area adjacent to the dark area that is also ground, but the galvanized coating is still present Рdepending on the thickness of coating left, this may be perfectly fine. The dark colour is a good indication of a future rust spot and a paint repair needs to be effected over this spot using a zinc rich paint.

bare over grind ground rust

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