Invented by the French artist Jean Baptiste Leprince (1734-1781) around 1765 to 1768, aquatint is an early screening process for producing gravure plates. The metal plate (generally copper) is firstly given a coating of finely distributed resin or asphalt grains. This is generally done by melting a fine powder onto the plate, though a number of other methods are also known. In the case of Craquelure aquatint, for example, a solution of colophonium resin in alcohol is applied to the plate. The resin is deposited when the alcohol dries and forms numerous fine, branch-like cracks. Those elements of the image which are not to be printed are then covered with an acid-resistant coating. Only those areas of the metal which are not covered with a coating are attacked during the subsequent acid treatment process. These are then able to accept ink during the subsequent printing process. This produces a screened contone area. By repeatedly masking further sections of the image and repeating the acid treatment, the etching process can be continued to achieve darker color tones.