Etching was discovered in the early 16th century. Rembrandt was the first to popularize this method. With this new technique available, engraving suffered a rapid decline. The artist does not have to cut directly into the plate - the acid does it for him. A metal plate (usually copper, zinc or steel) is covered with a thin layer of acid resistant black waxy ground. Using an etching needle, roulette (rotating wheel to rack) or mule (spinning roller rough) the artist draws through the ground freely (almost like pencil on paper) into the ground, exposing the bright metal below. The plate is then immersed in an acid bath (nitric acid or ferric chloride) which cuts lines ("bites") into the plate. The acid eats the plate where the protective ground was removed. The longer the acid bath, the deeper the lines (tones) will be. When different parts of the plate is left for different times in the acid depth and quality of the lines can be controlled. The remaining ground is then cleaned off the plate. The plate is inked all over, and then the ink wiped off the surface, leaving only the ink in the etched lines. The finished plate is then printed in the same way as engraving. The plate is then put through a high-pressure printing press together with a sheet of paper (often moistened to soften it). The paper picks up the ink from the etched lines, making a print. The process can be repeated many times; typically several hundred impressions (copies) could be printed before the plate shows much sign of wear.
     Colour Etching is achieved in two ways, either by using a separate plate for each colour or by carefully applying several colours on the same plate. Therefore the artist has to decide at the beginning which technique he wants to use.
     Etching has often been combined with other intaglio techniques such as engraving (e.g. Rembrandt) or aquatint (e.g. Goya).
     Etching by goldsmiths and other metal-workers in order to decorate metal items such as guns, armour, cups and plates has been known in Europe since the Middle Ages at least, and may go back to antiquity. The elaborate decoration of armour, in Germany anyway, was an art probably imported from Italy around the end of the 15th century.little earlier than the birth of etching as a printmaking technique. The process as applied to printmaking is believed to have been invented by Daniel Hopfer (circa 1470.1536) of Augsburg, Germany. Hopfer was a craftsman who decorated armour in this way, and applied the method to printmaking, using iron plates (many of which still exist).
     The 17th century is the great age of etching, with Rembrandt, Giovanni Benedetto Castiglione and many other masters. In the 18th Piranesi, Tiepolo and Daniel Chodowiecki are the best of a smaller number of fine etchers. In the 19th and early-20th century the Etching revival produced a host of lesser artists, but no really major figures. Etching is still widely practiced today.
     Soft Ground Etching
     The artist prepares the plate in much the same way as an etching, using a different kind of ground. This soft ground allows the artist, after laying a piece of paper on top, to draw the image with a hard pencil. The coating under the pressure of the pencil adheres to the paper which is then lifted off, exposing the metal underneath hereby creating an impression on the plate of the crayon marks. The paper with the attached ground is carefully removed and the plate is bitten. It is possible to reproduce any kind of texture with this method: textiles, rough papers, netting or leather can be pressed into a soft ground in a similar fashion. The print resembles a drawing.
     There exist: Relief etching, Non-toxic etching, Photo-etching.