Printing technique in which a metal plate
is first masked with an acid resistant usually a resin material,
then worked with an etching needle to creating an "Intalgio"image.
The exposed metal is exposed to an acid bath, creating depressions
that are later inked for printing. This technique was thought to
be deveoloped by Daniel Hopfer (1493-1536). Etching surpassed engraving
as the most poular graphic art produced during the prolific period
of Rembrandt as well as Hercules Segher in the 17th century. It
remains one of the most versatile and subtle known printing techniques.