On a recent trip to Cann Mills, Michael Stoate explained that the expression “show me your metal” was not a call for bravery, but a call for experience.
Once upon a time when there were stone mills up and down the land, there was enough work for professional stone dressers: people who prepared and maintained mill stones using iron “mill bills” as their tools. From time to time, little shards of iron would fly off the mill bills and embed themselves into the wrists and forearms of the stone dresser. On being asked to “show his metal” the stone dresser would roll up his sleeves and show off these scars as an indication of his experience.
How cool is that?