Mirrors date back to the Greco-Roman times, if not before. The disks were slightly convex and made of tin, silver or bronze that were highly polished. In 16th century in Venice, glass was backed with a combination of mercury and and tin. In 1835, the backs were coated with silver. Now, the glass is coated with silver or sputtered molten aluminium. The frames of the mirror reflected the period and ran the range from plainness to ornate.