Etching is another way of creating designs on the surface of a metal object. All of the previous ways of creating designs that we have discussed have relied on physical modification of the metal surface, that is, we stamped, molded, or cut the surface to create a design. Etching relies on a chemical process, which actually eats away the surface of the metal.
This picture shows the type of elaborate designs that are characteristic of etched pieces.
Before we go any further I want to emphasize the importance of using caution and safety equipment with this process. The worst thing that most of the previous processes would have done if we had made a mistake is a mashed finger or a cut (assuming that we are wearing eye protection). But etching is different in two major ways: 1. Etching creates fumes. Some of the etching processes can create toxic fumes, and some just create vapors which will cause your tools to rust – never a good thing. 2. Some of the chemicals that can be used can burn your skin and mar other surfaces, too. This short article is not intended as a set of instructions, but rather as an informative piece to give you an idea of the basic process of etching.
The process of etching works like this. First the metal is cleaned thoroughly, and the surface is roughened slightly by rubbing it with pumice powder.
The design is transferred to the surface, and any area where you want the metal to remain untouched by the chemical process is covered with a special material, called a resist. The resist will resist the efforts of the chemical to eat away the metal and a design will be created. The chemical literally eats away the surface of the metal.
So what chemicals do we use for etching metal? Well, it really does depend on the type of metal. The usual answer is an acid. Acid etching was the first form of etching that was developed. Etching was commonly used in the 1500’s to decorate armor and to create printing plates.
Modernly, if you are etching on copper or brass, you also have the option of using a less dangerous substance – a salt – Ferric Chloride. This liquid will not burn your skin, although it will dye it brown and can potentially cause your tools to rust.
The same basic process is used for Ferric Chloride etching as for acid etching. A resist is applied to protect the portions of the metal that you do NOT want to etch, and then the piece is placed into the Ferric Chloride. The best technique is to actually suspend the piece that you want to etch from a floating object. The etching process will create bubbles on the surface that is being etched. In order to insure that the etching process works evenly the item should be agitated gently to remove the bubbles.
Historically etching required a fairly large amount of hand work to create the designs. Modernly the designs can be created on a computer and printed on special transfer paper that will act as a resist when it is applied to the metal.
I hope that this brief article gives you a basic understanding of the etching process.
Next time: Granulation