Though many different types of metals may be etched, copper is one of the most common materials used in both traditional and modern etching contexts.
One of the few metals found abundantly in nature, copper is easily mined, refined, and 100% recyclable. This malleable and ductile metal is easily manufactured into strips, smooth rods or tubes, sheets and plates desirable for engraving.
The fine qualities of copper make it the preferred choice for etching as it bites evenly, holds texture well and color is not often distorted. Although green patina may develop over time when copper is exposed to environmental conditions, artistic etchings often utilize this attribute for a more integrated design.
While hobbyists and artists frequently utilize copper etching, industrial and commercial manufacturing also incorporate this medium in a variety of applications. Aerospace, automotive, transportation, electronics, minting and medical industries all utilize copper etching in metal components.
The popularity of copper in many of these settings can be attributed to its being one of the best known and most cost effective conductors of heat and electricity.
For this reason and others etched copper products include microchips, statues, decorative ornaments, printed circuit boards, musical instruments, piping, tubing, cookware, coinage and even ammunition.
Such a wide variety of copper etched products reflects the many different etching techniques available. While hand etching with a needle is popular in artistic and custom applications, chemical etching or machining is the most common industrial etching method, particularly acid etching and photofabrication.
Acid etching is accomplished by covering the copper surface to be etched with an acid resistant waxy ground. The manufacturer scratches off the ground, using a point etching needle creating the design of the finished piece.
The copper sheet is then dipped into acid or has acid washed over the metal. Photofabrication follows a similar procedure but rather than a waxy ground, the copper is covered in a photoresist and exposed to UV light to create the template necessary before the corrosive chemical is applied.
In either instance, the chemical wash bites into the metal where it is unprotected, leaving a depression in the plate. The depth of the groove depends on the length of application.
When the desired depth is achieved, the remaining chemicals are washed off and the rest of the wax or photoresist is removed to reveal the finished product. Cupric chloride is the chemical most often used with copper due to its high etch rate, though iron chloride and nitric acid are also compatible with copper.