plating, anodizing, & finishing Q&As since 1989
INDUSTRY ACCEPTED COSMETIC STANDARD, ZINC PLATING
AGE OLD QUESTION . . . IS THERE ANY INDUSTRY ACCEPTED STANDARD FOR COSMETIC INSPECTION OF ZINC PLATED PARTS? AT WHAT POINT DO WATER MARKS, STAINS AND DULL SHADOWS BECOME A REASON TO REJECT PARTS. WE UNDERSTAND THAT ZINC IS NOT A COSMETIC FINISH BUT ALWAYS SEEM TO HAVE AN ARGUMENT ABOUT WHAT IS ACCEPTABLE AND WHAT IS NOT. WE TRIED INSPECTING TO THE LAST LOT BUT OUR PLATERS TAKE EXCEPTION TO THAT CLAIMING THE PROCESS IS GOING TO BE INCONSISTENT. DOES A FORMAL, WRITTEN AND INDUSTRY ACCEPTED STANDARD EXIST? IF NOT ANY SUGGESTIONS FOR HOW TO APPROACH THIS ISSUE?TONY EMRICH
- MONTGOMERYVILLE, Pennsylvania
No such standards exist to my knowledge, but I don't think I can agree than zinc plating is always a non-decorative finish. Bicycle wheels have been acid zinc plated, then lacquered, as a less expensive substitute for nickel-chrome plating. I think I'd call that a cosmetic application. In-house standards are probably the only way to go.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
You don't say what type of zinc plating (non-cyanide, alkaline or chloride). Barrel (bulk) or rack? Clear, yellow, black or olive drab? Screws, flat stamping, etc? Is everyone at your company in total agreement to what is acceptable? Has the plater been told what is expected of them? Get the owner or GM at the plater involved if he hasn't been.
Make sure the exist plater knows what the parts are to look like. If they can't do it, try another zinc plater. But make sure they are informed what you expect.Bill Hemp
tech svc. w/ chemical supplier - Grand Rapids, Michigan
Mutually acceptable limit - samples are the way to go.
Bengaluru, Karnataka, India
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