screwed, blued and tattooed

Unlike the imaginative explanations given, the definition goes way back to early machinists. After inspecting a finished manufactured or repaired part, the Toolmaker/machinist would

1 tighten all parts and screws (Screwed)
2 Use Blueing a blue paint lke stain that stuck easaly to metal (blued) and
3 Put his inspectors mark through the blue paint with a sharp scriber (tattooed)

The part has passed inspection, it's been screwed, blued and tattooed and ready for release from the machine shop.

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