The work they do includes rebuilding a gun's stocks, hardening the frame, blueing the trigger and rebrowning, reboring and repolishing the barrels.
From the money.cnn.com
Steel plate armour for Henry II of France made in 1555 is covered with meticulous embossing, which has been subjected to blueing, silvering and gilding.
From the en.wikipedia.org
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Blue color or pigment; resembling the color of the clear sky in the daytime; "he had eyes of bright blue"
Of the color intermediate between green and violet; having a color similar to that of a clear unclouded sky; "October's bright blue weather"- Helen Hunt Jackson; "a blue flame"; "blue haze of tobacco smoke"
Turn blue
Blue clothing; "she was wearing blue"
Used to signify the Union forces in the American Civil War (who wore blue uniforms); "a ragged blue line"
Any organization or party whose uniforms or badges are blue; "the Union army was a vast blue"
Blue is the colour between violet and green on the optical spectrum of visible light. Human eyes perceive blue when observing light with a wavelength between 450 and 495 nanometres. Blues with a higher frequency and thus a shorter wavelength gradually look more violet, while those with a lower frequency and a longer wavelength gradually appear more green...
The Kalvertoren, a shopping center in Amsterdam, is located on Kalverstraat, Amsterdam's busiest shopping street.
Blue is the twelfth and final feature film by director Derek Jarman, released just four months before his death by AIDS-related complications. Such complications had already rendered him partially blind at the time of the film's release.