BYU's website is a nice place to start all queries. They mention HF:HNO3 [
http://www.ee.byu.edu/cleanroom/wet_etch.phtml ]  for etching stainless
steel.

On Fri, May 2, 2008 at 1:17 PM, Novak Farrington <
novak.farrington@manchester.ac.uk> wrote:

> Hi All,
>
> Does anyone know of a wet chemical etch for 316L stainless steel? We're
> trying to uniformly etch away, or at least thin, 100um of stainless steel
> from a magnesium diboride core. It would be nice if the magnesium diboride
> core was not etched, or at least etched at a much slower rate than the
> stainless steel.
>