Galvanic Etching

I have been interested in making etchings in brass and copper for some time, and in fact made a card box out of copper, with a scene from Alice's Adventures in Wonderland Galvanically etched into the front. Once I had finished that, I lent my etching tank to a good friend of mine, and I only recently got it back. But now that it's back on my workbench, I am going to improve the quality of my existing etching skills, and broaden my repotoire of techniques. I'm going to start with a brief history of Galvanic etching first though. The benefit of the ability to etch images and words into various metals was twofold. They were used in printing, where the plates would be of the Intaglio variety, where the raised part of the image were the lines desired on the final piece, a negative of the final image if you like. As well as this, etched plates can be quite aesthetically appealing. Galvanic etching, also known as electrolytic, or electro etching, is a process that has been known since the 19th century, the original description of the process having been published in 1855 under the name electro-etching. Prior the widspread use of electrolytic etching, acids had been used in their place, these acids included nitric acid, hydrocloric acid, or ferric chloride. None of which are particularly pleasant chemicals (http://www.greenart.info/galvetch/advan.htm). The basic theory of Galvanic etching is this: If you suspend two plates of metal (both based on the same metal, that is, if you have a copper plate, you can couple it with brass, copper, or bronze) parrallel to each other in a solution of the same metal (in a salt form usually), and pass an electric current from one to the other, particles of one plate will become dissolved in the solution, and will then be dposited on the other plate. Electro-etching is essentially the polar opposite of electroplating.

In this diagram, sorry for its low quality by the way, the brass plate is on the left, and the copper is on the right. The plate connected to the negative supply is always the cathode, or K, and the positive is always the anode, or A. When you etch, your piece is always the anode, and a bit of appropriate scrap is the cathode. Reverse this for plating.