Hello. KOH should work and it is less dangerous in handling, compared to HF. Best regards, Norbert Nodes EV Group E-Mail: n.nodes@evgroup.com, www.EVGroup.com -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Gary Hillman Sent: Mittwoch, 10. Oktober 2007 19:02 To: 'jpt sharma'; 'General MEMS discussion' Subject: RE: [mems-talk] Al2O3 J. Alumina is really pretty chemically resistant. The only thing that I think will touch it is HF and then VERY slowly. Gary