Etching (the English word is related to the German “ätzen”, to engrave by eating away the surface) is a manual intaglio process where strong acid or mordant is used to cut into the unprotected parts of a metal surface which is then used for printmaking. This technique was first used in 1510 and the fundamental principles have not changed until today.
A copper surface is cleaned and polished, then coated with an acid-proof material, a mixture of wax, mastic gum, bitumen and pitch. This coating has to be resilient enough to withstand etching at a later stage but it must not resist the etching needle too much. Once this stage has been completed, you can start drawing on the coating. A needle or another type of tool is used to remove it and to expose the copper surface again.
Once the drawing is finished, the etching process will start. The copper plate is placed in an acid bath with the drawing facing upwards. Nitric acid or ferric chloride is used as a mordant. The depth of the etching – i.e. the drawing – depends on the time the copper plate is left in the bath. For strong black lines, the plate often has to be left in the acid for several hours. After etching, the plate is rinsed off and cleaned with turpentine. Then, it is prepared for printing. The plate is heated, inked up with copper-plate printing ink with a roller or by dabbing and wiped until there is no more ink left outside the incised lines. Damp handmade paper is then run through the copperplate press to produce the print.