Scott: "Rust" is simply an insoluble compound of the base metal, in this case Copper. If you use that rather broad definition, the OSP coating itself qualifies as being "rust", as it is an insoluble, if organic, compound of Copper. So, if your test useds NaCl to dissolve the "rust", you could very well be dissolving the coating itself, and seeing it as "rust". Hope this helps. Rudy Sedlak RD Chemical Company --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------