So I am looking for a recommendation on an acid to use that will etch but not stain. ferric leaves an ugly stain. Suggestions?

Roger, I've only used ferric. It's been years since I've made any pc boards.

I had a friends dad who worked as a chemist at Monsanto in St. Louis make me a super concentrated solution of it. Worked great!

Good luck finding something.

According to this article ammonium persulfate is also used to etch Cu circuit boards

http://www.dummies.com/WileyCDA/DummiesArticle/Showing-You-My-Etchings-Etching-t he-Circuit-Board.id-2921,subcat-HOBBIES.html

But I have never used anything but Ferric Chloride.