After mounting the target on a frame (e.g. epoxy) prepare the target for etching by dipping it in trichloroethylene - UN1710, a degreaser. Next prepare the solution:
75 mL of 23% Ammonium Hydroxide - UN2672 (NH4OH)
25 mL 50% H2O2.
Dip the foil in the solution and a blue discoloration will immediately appear, see picture. Remove after bubbling has ceased. If the solution bubbles over, use less hydrogen peroxide. Dip the foil again in trichloroethylene .
1.0 MeV Protons Backscattered (165 degrees) off the nickel foil.