A photomechanical technique related to the cliché-verre and the lithograph. A surface (usually heavy plate glass) is coated with light-sensitive gelatine and exposed to light under a photographic negative. The areas exposed to more light harden, whereas those that are not remain capable of absorbing moisture. The surface can then be inked up and printed from lithographically, the moist areas rejecting ink, the dryer ones accepting it. The collotype was developed in Germany and France at the end of the 1860s. Until the advent of the half-tone screen it was the only photomechanical process able to reproduce tone (apart from hand photogravure). Unfortunately the delicate gelatine surface was only capable of yielding a maximum of about 2,000 impressions, therefore commercial viability was strictly limited. The collotype was therefore restricted to luxury publications and was largely abandoned after the Second World War.