IMPORTANT UPDATE: Since posting the information below regarding the use of kosher salt for etching metal, I have continued to research the technique and now know that I was right to question the safety issues involved. I stopped using the salt and will be switching to using copper nitrate instead. Anyone interested can read about this in the excellent, well illustrated 13 page PDF created by Ben Dory.
Once I have it all up and working again, I’ll post my results.
Anyone interested in etching metal in their own studios should read this excellent book first. Coral Schaffer covers a great variety of techniques, including (but not limited to) electro-etching. In particular, I value the safety information provided for the various methods included in the book.
In reading many blogs and posts related to electro-etching with salt water and some power source (including batteries), I see that most think of the salt water methods as “safer” than methods using ferric chloride. This is a misconception in my opinion. While salt water may be less messy, cheaper, and easy to make, it is only as “safe” as the methods used. It still results in copper dissolved in a solution that is bad for the environment, not safe for contact with skin, eyes, etc.. The copper rich salt water must be disposed of at a hazardous waste drop-off location.
If you etch with salt water, follow all safety instructions carefully. Gloves, eye protection, good ventilation, and proper disposal of copper rich water.