I have a customer who is using standard aqueous dry film on #301, #302 &
#316L stainless steel and then etching with ferric chloride (this is actually
a chemical milling process, not really printed circuits). He is having slight
undercut under the dry film which dulls the surface (unacceptable to his
customer). He is using 45 Baume strength ferric chloride and has asked if
either lower or higher strength would work better and not cause the undercut.
Any ideas out there?

Regards,

Larry Fisher