You should correct the amount of H2O...I think 985 ml are too much! > This is what I used to etch Cr. It should be safe with oxide. You need > to check if it is OK with PMMA. There are also commercial etchants you > can buy. > > Nichrome Etch: 155 g (NHb4)2Ce(NO3)6 (Ceric Ammonium Nitrate) + 60 ml > HNO3 + 985 ml H2O