Etch

Etch, in general, refers to the process of removing material from a surface to create a design or pattern. The term is used in art, manufacturing, and electronics and can involve acids, solvents, or physical energy such as plasma. Etching can be intentional or decorative, and its outcome depends on the method and materials used.

In traditional art, etching is a printmaking technique. A metal plate, usually copper or zinc, is coated with a resist. An artist cuts lines through the resist, exposing the metal. The plate is then immersed in an acid bath that bites into the exposed metal, forming recessed lines. After cleaning and inking the plate, paper is pressed onto it to transfer the image. Variations include aquatint, which uses powdered resin to create tonal areas, and drypoint, where the needle itself raises a burr for rough lines. Notable practitioners include Rembrandt and Goya.

Industrial etching encompasses chemical and physical methods used to remove material for manufacturing. Chemical etching uses acids or alkalis, often with a masking layer to protect areas that must remain. Photochemical machining uses masks and light to define features before etching. Dry etching, used in semiconductor fabrication, employs plasma or ion beams to remove material with high precision, enabling microelectronic circuits, MEMS devices, and solar cells. Etching is also used to decorate glass and metal surfaces.

Safety and environmental considerations are important. Many etchants are corrosive and toxic; operations require proper ventilation, protective equipment, and waste treatment.