The burr prints as a dark, velvety accent, but wears down quickly under the pressure of printing. For this reason, very few impressions will exist with the rich drypoint details intact. In contrast, etching is a process by which a copper plate is coated with an acid-resistant resin and an etching needle is used to scratch through the resin to form an image. When the plate is immersed in acid, the acid eats only into the scratched areas. Before printing, the resin is removed, leaving a clean copper surface with etched lines.
Thick ink is spread over the plate and forced into the lines.
The plate is then wiped to remove excess ink. The inked plate and a damp sheet of paper then are run through a roller-bed press, transferring the image in reverse to the paper. A state is any stage in the development of a print at which impressions are taken. States change only with the addition or removal of lines on the plate. The use of more or less ink to produce impressions of varying contrast does not constitute a new state.