A technique used in Intaglio etchings. Like etching, aquatint technique involves the application of acid to make marks in a metal plate. Where the etching technique uses a needle to make lines that retain ink, aquatint relies on powdered rosin which is acid resistant in the ground to create a tonal effect. The rosin is applied in a light dusting by a fan booth, the rosin is then cooked until set on the plate. At this time the rosin can be burnished or scratched out to affect its tonal qualities. The tonal variation is controlled by the level of acid exposure over large areas, and thus the image is shaped by large sections at a time.
It is usually combined with a standard etching ground that permits lines and clear white areas as well. The final effect is an image on a fine pebbled background (imparted by the porous ground). Aquatint is usually employed in combination with line etching when subtle value gradations are desired.