GUN BLUE

I learned about gun blue while working in the wardrobe department.  We used it to tone down the shine of metal buttons and buckles so that they would not glint and gleam on camera. Metals containing iron will turn blue-black when they comes in contact with the gun blue as magnetite (Fe₃O₄), the black oxide of iron, forms, also creating protection against corrosion and rust.  This is a wonderful trick to use if you're trying to age or dull down hardware.  Be sure to wear gloves and eye protection as this is a toxic product.

I used gun blue recently to tone down the shine of the above links for an installation at Fort York in Toronto.  In retrospect, my labours were probably not necessary as the links were high in the air and not very visible.  However, I always enjoy seeing the instant transformation from bright-shine to ancient-artifact.