Lefranc and Bourgeois Charbonnel Lithographic Ink Rubbing Up Black 800ml Charbonnel offers 3 types of black adapted to a specific use: Pencil black (light colour); drawing black (medium) and velvet black (deep).  The varnishes are essential to modify the rendering by playing on the consistency of the inks themselves. The weak 30-poise varnish will make the inks more fluid and therefore more transparent. The strong varnish 200 poise is used to thicken the inks. Brand: Lefranc and Bourgeois Lithography is an engraving technique invented in 1796 by Aloyw Senefelder in Munich, which soon attracted the attention of numerous artists such as Goya, who showed its great possibilities as early as 1819. It is a printing process that consists of reproducing on paper what is drawn with a special ink or greasy pencil (lithographic bar) on the surface of a compact and very homogeneous limestone. This limestone is in the form of a thick plate with two parallel opposite sides, one of which is finely polished and with the edges cut off.