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Passivation of electroless silver with tin chloride solution

We're probably all aware of tin chloride sensitising of non-conductive substrates prior to electroless deposition (silver onto glass, for example) I've also heard that the tin chloride treatment can be repeated on top of the silver as a protector against corrosion. Is anybody aware of this and is it used in other plating applications to protect the silver?

David Bamber
- UK
1999

I'm also interested on that subject. I don't know how to establish if the silver layer is passivated or not after treatment with tin chloride. May be with Salt Spray Test, mirrors with treatment and mirrors without it? May be Lavalle Test? (I prefer this one) It would be very helpful if you have more comments.

Carlos A Ramirez
- Santafe de Bogota
1999

Silver easily forms the intermetallic, Ag3Sn. This can be formed by electroplating and by pulse plating, and was looked into about 15 years ago to protect silver. If immersion tin were taken to completion I would suggest to "fix" it by heat treatment in an oven to 250-350°F for 20-10 minutes. The sulfide tests are good for quick evaluation.

Steve Koelzer
- Sunnyvale, California
2000