Most etching is probably done on printed circuit boards -etching
copper off. Most art related etching is done in printmaking etching
various materials but not the precious metals. Enamelers will etch
copper and silver mostly.
I have posted on this ad nausea-- search archives but here are some
sources. The circuit board etches will not work on silver. It
requires ferric nitrate for a chemical etch.
The electrolytic systems are the safest from a chemical exposure
standpoint.
http://perso.club-internet.fr/gravert/galvetch/contfram.htm
http://www.art.eku.edu/programs/print/tech/Etching%20procedure.html
http://www.enamelandtiffany.com/spectechn/photogravure.htm
http://www.artmondo.net/printworks/articles/afnte.htm
http://gravert.club.fr/galvetch/contfram.htm
http://www.printstudio.org.au/sa/copetch.html
http://www.kahiko.com/Electro%20Etch%20Silver.htm
http://www.culttvman.com/acid-etching_part_2.html
http://www.enamellers.nl/technieken.php?l=uk
There are many more. also search resists - Orchid first then google.
material availability may depend on where you live so it helps to
give a general idea.
Hazmat “rules” are often not correctly applied-- you can’t do much
about this.
read and enjoy
jesse