Where the
world gathers for metal finishing
Q&As since 1989


-----

Test Anti-Tarnish on Silver Plating

July 7, 2009

Can anyone tell me the proper test to use to determine if my silver plated parts are properly protected with an adequate Anti-Tarnish barrier? I have read 2% Hydrogen sulfide, but that is hard to find, at least it is not at the high school or college here in town.

My issue is that the aluminum parts that we machine are sent out and Silver Plated
per QQ-S-365D and are Type II Grade A. Grade A requires that an anti-tarnish be applied. Well anyway we have tried 3 different platers and have the same results, which are.

Unwrap parts from Silver Saver Paper with gloves.
Place parts into machine and tap/chase threaded holes.
(Use Water Based Coolant or Vegetable Oil)
Remove part from machine.
Dip in room temperature RO Water (water alone does not stain the part)
Blow off excess water
Re-wrap in Silver Saver.

So minutes after re-wrapping the parts starts to turn Yellow and more times than not develop several tarnish spots on it. Cases have been a couple of small spots on the face of the part to numerous large and small specs all over the part.

We have made and processed these parts for years without any issues, now all of a sudden we cannot get 1 good part. I do not recall changing anything in the process, the cooling oils are still the same. ANY IDEAS?

Dan Brinkman
Engineer - South Dakota

---

July 8, 2009

Hi, Dan. I think you will find letter 5675 interesting. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey