Electro-etching, or galv-etch, is an electrical etching technique that can be practiced conveniently and safely at home without the need for expensive equipment or the use of harmful acids. This technique allows for a wide range of tonal effects, a surprisingly clean bite, increased control, all while minimizing the risk to the both the printmaker and the environment.
To electro-etch a metal plate you need nothing more than electricity and a conductive solution of a salt. Electro-etching takes place in a tank filled with a solution of copper sulfate, in the case of etching a copper plate. A power supply of direct current is also needed. Once the plate has been protected with a ground and the lines are drawn to etch, the plate is submerged in the tank and connected to the positive pole of the power supply. Several centimeters away, another copper plate is connected to the negative pole. When current is passed through this arrangement, usually less than 1 volt, the tiny particles from the plate to be etched are drawn to the negative pole of the other plate, thus etching occurs. Variations of this basic technique are near endless.
Read more about electro-etching: Electro-etching Made Easy, an article by Alfonso Crujera