Etching is a practice that dates back to early civilization. Initially, it emerged as a method of adding aesthetic embellishments to items made of soft metals like zinc and copper, and strong metals like steel. Etchings were added to items such as plates, cups and, later, armor and guns, with the use of strong acids.
Metal etching began to have greater impact on society during the 16th century, when it was first used for printmaking in Germany. This act ushered in the Printing Revolution and prepared Europe for the Industrial Revolution that was to follow. To make prints, artists practiced the following process: First, cover a metal plate in an acid-resistant material, usually wax, and then scrape it away to expose the metal. After exposing the metal, create a printing die using a sharp etching needle. Continue scraping and then proceed to bath the plate in an acid or etchant, thus dissolving the exposed metal and creating sunken lines and words. Once this procedure has been completed, you have metal plates that you can ink and use for large scale printing.
Elsewhere and simultaneously, metal etching was emerging as an alternative to that period’s preferred method of metal patterning, metal engraving. Not long after that, chemically etched plates, found to be very durable, were used to inscribe trajectory information onto artilleries and canons. This led to the practice of milling or etching information onto shovels, various types of equipment and stiletto daggers.
In the 18th century, a Swiss botanist named John Senebier discovered a piece of information that led to the next innovation in chemical milling. He discovered that some plant resins hardened and lost their solubility to turpentine, after being exposed to light. This realization, while for several decades applied to photography, brought us much further down the road to modern photochemical etching. By applying a liquid form of resin to metal and exposing it to light, manufacturers were able to create an outline of the masked area, an impression on a metal plate.
The next shift in photochemical metal etching, the commercial method we use to this day, came to be in 1927. At this time, this method was developed and patented to produce and cut gap & edge filters, by a Swedish Company named Aktiebolaget Separator. The method allowed metal to be etched from both sides, perfect for sheet foil. As World War II got underway, this method gained popularity and was widely used for machining hard metal parts.
The final page of metal etching’s history book, as it stands today, references when it was adapted to support the micro-fabrications of the technology revolution that began in the 20th century and continues to evolve today. Amazingly, this practice that began so long ago, it is now used for applications from circuit printing, to missile skin production, to aerospace components. Only time will tell how far etching will take us.