I'm having a tough time finding ferric chloride. Pretty tough to imagine in
a large metro area (Chicago), but TV retailers is all I find under
Electronics in the yellow pages. If I buy bulk anhydrous, what dilution
should I make the working solution? I saw 40% by weight on MG's website and
other places. (What, exactly, is a Baume? as in: "To form the basic stock
etching solution, water is added in the ratio 2 parts water to 1 part ferric
chloride solution in a solution strength of 42° Baume.")
(
http://www.polymetaal.nl/beguin/mapf/ferric_chloride.htm).