Copper Tarnishing: Smart Fixes for a Persistent Problem

Summary for copper tarnishing Discussion

Copper tarnishing on plated parts was the core problem in this thread: Kannan Boopathi said he was barrel plating 1.2 mm sheet with cyanide copper undercoat, acid copper topcoat, and an anti-tarnish top coat, yet still seeing tarnish despite careful packing. Mark Baker advised checking several likely causes, especially metallic impurities in the copper bath, the quality of the final rinse, and whether a hot DI rinse is being used, since water quality is often the culprit. Later, Madhukar Nandakumar asked about using tollytriazole or benzotriazole and how to detect poor anti-tarnish treatment quickly. The reply said benzotriazole is a good answer, but recommended going to the plating chemical supplier for a copper tarnish preventer, likely triazole-based, so the supplier can provide instructions and ongoing support. The discussion points to bath cleanliness, rinse quality, and supplier-backed anti-tarnish chemistry as the main practical checks.