Are you sure on the NH4F safety? My understanding is that this simply dissociates into HF once it is combined with water. Whenever I use etchants with NH4F or ammonium biflouride I treat them like HF. Dave _______________________________________________ Hosted by the MEMS and Nanotechnology Exchange, the country's leading provider of MEMS and Nanotechnology design and fabrication services. Visit us at http://www.mems-exchange.org Want to advertise to this community? See http://www.memsnet.org To unsubscribe: http://mail.mems-exchange.org/mailman/listinfo/mems-talk