Aquatint

An etching technique that produces an unlimited number of gradations of tone from black to a very pale gray. It usually will have a granular appearance. The name is not from the actual technique, but in its visual similarity to that of a watercolor. The technique is usually used in conjunction with other processes such as engraving or drypoint. The majority of Goya's prints are done in a combination of aquatint and etched lines.