The History of Chemical Etching
Chemical etching, as we know it today, was derived from the metal etching and printmaking processes of the Renaissance period in Medieval Europe.
Metal etching first appeared in Medieval Europe in the early 15th century and was used aesthetically to decorate metal armor, cups and other metal objects. The chemical etching process of medieval days worked very similar to modern day etching. Artists would apply a protective coating of linseed-oil paint to select areas of metal. The coating would act as a resist, protecting the metal. A chemical etchant mix of salt, charcoal and vinegar was then applied to the metal, etching through the unprotected areas and leaving behind the protected design1.
The chemical etching process arrived in Germany by the end of the century, possibly brought there by Italian artisans.
In the 16th century, a German artisan named Daniel Hopfer subsequently extended the chemical etching process to printmaking using iron prints. Hopfer applied ink to an etched metal plate and then wiped away the excess. Paper subsequently pressed to the plate had the inked image transferred to its surface.
In the 17th century, Jacques Callot, a baroque printmaker and draftsman, made several contributions to metal etching that allowed it to more adequately challenge metal engraving as the preferred medium for artists. Callot invented the échoppe, a slanted etching needle that allowed for more intricate lines; improved the etching ground (resist) used to prevent acid from biting through to certain parts of the metal; and perfected the art of "stoppings-out", a technique that allowed metal etchers to use acid to create different shades of light on the metal2.
It was in the 17th century that chemical etching first became used for industrial purposes, and was used to etch metal measuring instruments and scales for military use.
Additional discoveries further extended the principles of chemical metal etching to photochemical etching in the late 18th century, which ultimately enabled a photographic process where exposure to UV light produced images on metal plates.
The discovery of hydrofluoric acid in the 19th century enabled glass etching, and in the early 20th century, the development of stronger resists allowed more highly corrosive etchants to be used on stronger metals.
In 1944, John Snellman patented the process of using outlines in a photoresist template to batch produce uniform, flat components out of metal that was too hard to stamp or cut with traditional machining methods3.
In the 1960's, the creation of the printed circuit board further spearheaded the growth and development of the chemical etching process for commercial use.
Today, chemical etching is used in the manufacture of aerospace parts, printed circuit boards, semiconductors, nanotechnology, medical devices, rf shielding and more. Chemical etching now offers the flexibility or producing intricate parts with tight tolerances (within .0005"). Using state-of-the-art CAD, resolutions of 1/4 mil are routinely achieved.
Fotofab is on the cutting edge of chemical etching technology. From custom screens and springs, to antennas, contacts, connectors, washers, rf shields and more, Fotofab produces the highest quality precision metal parts to your exact specifications.