Common Etchants for Copper, Nickel and Cobalt: Copper & Alloys

Composition	Comments
2 5 mL NH4OH 25 mL water (optional) 25-50 mL H2O2 (3%)	General purpose grain contrasts etch for Cu and alloys (produces a flat etch for some alloys). Use fresh, add peroxide last. Use under a hood. Swab specimen 5-45 seconds.
100 mL water 10 g ammonium persulfate orientation.	General purposes etch for Cu and alloys. Immerse or swab for 3-60 seconds. Reveals grain boundaries but is sensitive to crystallographic
100 mL water 3g ammonium persulfate 1mL NH4OH	General purpose etch for Cu and alloys, particularly Cu-Be alloys.
70 mL water 5 g Fe(NO3)3 25 mL HCI	Excellent general purpose etch, reveals grain boundaries well. Immerse specimen 10-30 seconds