electro-tint

 A style of engraving in relief by means of voltaic electricity. A picture is drawn on a metallic plate with some material which resists the fluids of a battery; so that, in electro-typing, the parts not covered by the varnish, etc., receive a deposition of metal, and produce the required copy in intaglio. A cast of this is then the plate for printing.  [1913 Webster]