Ink is a colouring agent intended for writing, for drawing and for impression.
It can be liquid, pasty or solid, usable on various surfaces, but its usual support remains paper. First inks were based on black pigments of smoke and vegetable dyes, on solution in disposition with most diverse formulaes. According to their composition and use, inks can be divided into ferro-Gallic base ink, Campêche based ink, Marking inks, Colored ink, Drawing or Invisible inks.
Main inks used for drawings are China ink, Gall nut ink, Bistre, Sepia and Colored ink are rarer.