Here's a link on cleaning silver using a variation on the method described above:
And I have been searching for a picture of the "charro" style jewelry from Salamanca--I have a "botón" on a keychain and a lovely silver pin. The wallpaper on this page depicts one of the typical "buttons:"
Here's another link, with a reasonable photo: http://kionet.virtualave.net/salam.html
And a few other photos here: http://www.terra.es/personal6/tamames1/FILIGRANA.html
I get so many compliments on my silver "botón charro" pin--I wear it on the lapel of my winter jacket.