protecting copper with benzotriazole

I was told years ago that benzotriazole ("slightly soluble in alcohol"), when applied to a copper surface, will protect the surface from corrosion from the air ("forms a monomolecular layer on copper and silver which precludes most other chemistry, especially tarnishing"). I think benzotriazole used to be a common additive to silver polish? I recently tried this out and the treated surface was identical to untreated when exposed to H2S (boiled eggs in a sealed container). Some possibilities:


* ~~I was lied to!~~
* The application process requires subtleties that I missed
* H2S is not "most other chemistry" and I should have tested with something else
* my container of benzotriazole from ebay isn't benzotriazole


Looking for suggestions for further experiments or alternative processes.


