"a colour almost like the backing of mirrors"

Woman looking in mirror, crayon drawing, 1918
Public DomainWoman looking in mirror, crayon drawing, 1918
According to answers.com, "Silver was the most popular mirror backing one hundred years ago. . . . More recently, before 1940, mirror manufacturers used mercury because it spread evenly over the surface of the glass and did not tarnish. This practice . . . posed the problem of sealing in the toxic liquid. Today, aluminum is the most commonly used metallic coating for mirrors."