A gravure printing technique related to copper engraving. Steel plates, softened by the deprivation of carbon, serve as printing plates. Thus the image to be printed can easily be etched into the plate. Then the plates are hardened again and used just like copper plates. Because of their hardness they last longer than copper plates and can be used for high-output printing. Steel engravings are characterised by particularly sharp contours. In the 19th century this technique was mainly used to reproduce paintings and drawings, to print maps and illustrate books.