Good Morning, I need some information if available. I am finding on our lead free solder irons that there is a black substance that is rising up the soldering shaft. We are currently using an Aim 270WR flux, SN100C LF Solder, LF tinner, Solder iron temp is 720, they are WD1 solder irons. Can anyone give me some information on what this black substance may be? Thanks Gloria phone 906-932-5970 ext. 26 fax 906-932-9822 [log in to unmask] --------------------------------------------------- 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 847-615-7100 ext.2815 -----------------------------------------------------