plating, anodizing, & finishing Q&As since 1989
Using lead to repair dents in copper before gold plating
December 29, 2011
Q. Dear fellow metal workers, I am in the process of prepping copper sinks that will be gold plated. However, some areas are inacessible to remove indentations caused in production. I am planning to fill the damage with lead solder, would this affect the plating processDavid Sandford
First of two simultaneous responses -- December 29, 2011
Be aware that in time the copper and lead will migrate right through the gold and corrode on top. You need a diffusion barrier of palladium or nickel between the copper/lead and the gold. Also. to plate over lead you need to prepare the surface with a dip in fluoboric acid. Lead forms an insoluble salt with sulfates and chlorides, then later the plating peals off.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
Second of two simultaneous responses -- January 1, 2012
Lead will absolutely alter your subsequent plating, maybe to the point of making it a total failure. Why not brush plating with copper and dress back the surface to blend the repaired area. Acid copper solution will do a great job. Very fast and localized build-up, no corrosion to surrounding copper, little or no masking, no need to heat the part, no need to change your subsequent gold plating process, etc, etc. If dents are too deep (+1/32") silver brazing would be an option.
Monterrey, NL, Mexico