Though many different types of metals may be etched, brass is a common option. An alloy of zinc and copper, brass has many of the same properties of both metals. Additional elements can be added for beneficial properties. Aluminum, for example, is often added to increase strength and corrosion resistance.
Brass is softer than most other metals and etching takes a relatively short amount of time and requires minimal mechanical force. This malleable and ductile metal is easily manufactured into strips, smooth rods or tubes, sheets and plates desirable for engraving.
Artists and hobbyists often use brass as its softness allows for hand needle scratching. While brass is frequently utilized in these domestic settings, industrial and commercial manufacturing also incorporate this medium in a variety of applications.
Aerospace, automotive, transportation, electronics, minting and medical industries all utilize brass etching in metal components. Like copper, the popularity of brass 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 brass products include tubes, piping, welding and thermal processing equipment, weather stripping, locks, gears, doorknobs, valves, decorative embellishments, coinage and a wide variety of musical instruments.
Such a wide variety of brass 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 brass 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 brass 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 brass 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 brass due to its high etch rate, though iron chloride and nitric acid are also compatible with brass.