The Claude Glass or Lorraine Mirror was popular from the late 18th century. It consists of a black, slightly convex, mirror usually held in a case with hanging rings. It was used by professional artists and engravers as well as amateur artists. The glass is set up to face the scene, the artist then looks into the glass to see an image that is largely devoid of colour but where the major feature are distinct. The image is laterally reversed. The glass being in a fixed position would also have helped to maintain a set perspective. The mirror remained in use by engravers into the early 20th century.