Aquatint

Aquatint is a form of etching perfected in the 1770s particularly for the depiction of watercolour washes and tone.

The effect was created when a granulated resin (or powdered asphalt) ground was applied to a copper plate with heat. As it cooled the particles in the resin left a random pattern of exposed copper which when immersed in an acid bath etched a network of lines between the grains of resin producing a randomly speckled appearance to the image when printed.

Different tonalities were achieved by stopping out areas of the plate or coating particular areas of the plate with a different grained ground.

Spirit-grounds (resin suspended in alcohol) where employed to produce a reticulated pattern, with the coarser grains gravitating to the bottom, if the plate was inclined, resulting in a more realistic landscape effect.

It was not uncommon for either engraved or etched lines to be incorporated into the image.