Etching. Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio in the metal.
   In modern manufacturing, other chemicals may be used on other types of material. As a method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today.
   In a number of modern variants such as microfabrication etching and photochemical milling it is a crucial technique in much modern technology, including circuit boards. In traditional pure etching, a metal plate is covered with a waxy ground which is resistant to acid.
   The artist then scratches off the ground with a pointed etching needle where he or she wants a line to appear in the finished piece, so exposing the bare metal. The échoppe, a tool with a slanted oval section, is also used for swelling lines.
   The plate is then dipped in a bath of acid, technically called the mordant or etchant, or has acid washed over it. The acid bites into the metal to a depth depending on time and acid strength, leaving behind the drawing skillfully carved into the wax on the plate. The remaining ground is then cleaned off the plate. For first and renewed uses the plate is inked in any chosen non-corrosive ink all over and the surface ink drained and wiped clean, leaving ink in the etched forms. The plate is then
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