Nam

It has been noticed that stainless steel in a KOH solution contaminates the
bath and will make etched surfaces very rough (we also found this out the hard
way here) by leaving a residue on the surface. I don't see why that couldn't
happen in TMAH as well. PEEK is a better material for the chip holder.
Reference below.

T A Kwa et al  1995 J. Micromech. Microeng. 5 95-97

Dylan J. Morris, Ph.D.
Washington State University
Center for Materials Research