The classic test for clean Copper should work here... Put a drop of Silver Nitrate solution, the standard lab 0.1N Silver Nitrate is fine, on to the Copper. If the Copper is clean, it will turn an instanteous Black, and the black will not rub off with your finger. If it is not clean, the black stain will be slow to form, and the resulting black will be loose, and can be easily rubbed off. 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 To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------