Zinc Nickel Plating Dark Deposit: Serious Troubleshooting Clues

Summary for zinc nickel plating dark deposit Discussion

Zinc-nickel plating dark deposit in LCD areas is the issue Darren Ogden raised for an alkaline barrel line that starts to darken after about a month, especially on nuts. He suspected titanium barrel clamps touching the anode plates, possible rectifier contamination, and noted black sludge in the filter and tanks, plus zinc on the edges of the bottom anode plates. He said pretreatment was not the problem and that the chemistry was in spec. The excerpt provided contains only the question and no replies, so there is no confirmed diagnosis or fix in the thread text. The most useful clues are the recurring timing, the darkening in low-current-density areas, and the sludge/anode observations, which suggest the problem may be related to equipment contact, anode condition, or contamination rather than pretreatment.