Zn treated spokes often were on bikes with steel hub-shells*, so the J hook , head end, bend was tighter than subsequent and current spokes ,
assuming thicker Aluminum flange hubs..

I would not try to polish a Zn coated spoke , because doing so removes the rust resistance zinc offers..

*Such was the wheels on my Mk 2 Brompton AW 3 hub was marked as 94 era...






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