Most immersion Silver baths contain an anti-tarnish to prevent discoloration, as you see, for instance on your silverware at home, if you have the expensive stuff.. So, it could be a lack of, or lowered level, anti-tarnish in the plating bath... most of the immersion silver baths use triazole as the anti-tarnish, and there is a pretty easy test for triazoles from the Hach company, out of Colorado. If it is Copper showing through, as has been suggested, this could be because the silver deposit is porous, which can come from plating on to a dirty Copper surface...recall that the step before plating silver is to develop the soldermask, which is an "iffy" process, and has been known to leave some material behind. If the surface is dirty, the silver will not adhere real well, and a tape test would probably show that. Regards, Rudy Sedlak RD Chemical Company --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------