Etching is a printmaking process in which lines or areas are etched into a metal plate using acid. The plate can be made of iron, copper, or zinc. These lines or areas then hold ink that can be transferred onto a medium, usually paper, but other mediums are possible.
To prepare for etching, the plate must first be polished to remove all scratches and imperfections from the surface. Then it’s covered with an acid resistant varnish, which comes in different variants, such as soft ground and hard ground.
A design is then etched into the varnish, exposing the metal, after which the plate is bathed is acid. The acid eats away at the parts of the plate where the varnish has been etched away, engraving the design into the plate. The depth of the design is determined by the length of time the plate is exposed to the acid, deeper lines in the plate means darker lines on the paper.
This process can be repeated several times to create different tones. Once satisfied, the printmaker removes the varnish and the plate is ready for inking.
Ink is spread evenly onto the plate and any excess is removed from the surface. After this the plate is placed on the bed of a rolling printing press together with the paper. The pressure from the print presses the ink onto the paper.
Aquatint is a printmaking technique that produces tonal effects by using acid to eat into the printing plate creating sunken areas which hold the ink. Damar Rosin or Colophonium are widely used to produce this tonal effect by sprinkling it on the metal surface and fusing it using a flame torch then blocking out the non-printing area before etching it in an acid bath. A sugar lift is a way of creating painterly marks on an etching plate using a sugar solution and a paintbrush. The areas you paint are a positive mark. It is a form of aquatint etching.
Soft ground etching involves coating the metal plate with a very soft ground that can be removed with just a bit of pressure. To make a design on soft ground, the artist places paper over the soft ground plate, and then draws on the paper with a pen or pencil. Where the paper presses into the soft ground, it sticks to the underside of the paper. When the artist lifts the paper, the lines of soft ground also come up, stuck to the back of the paper. The image appears as lines of exposed metal on the plate, which can then be etched in Acid bath.