I am looking for a process to etch Zerodur - glass ceramic.
Until now I etched the Zerodur 'M' by Ammonium bi Fluoride and I got smooth
surface and full transparency.

Now I tried to etch the Zerodur by the Ammonium bi Fluoride but I lost the
transparency and the smooth surface- actually   the Zerodur 'M' block I etched
is opaque.

I tried to change the etching parameters – time, concentration an temperature
but I did not succeed to get the transparency and the surface quality.

Do you have any idea what to do ?

Thank you