Great answer Mr. Stern. May I add that what is done with the spent etchant can also dramatically effect cost of stripping. With Ammoniacal, the spent is always returned, usually at the cost to the generator, to the supplier of etchant. Cupric, regenerated with either Chorine, or Hydrogen Peroxide has the POSSIBILITY of becoming a commercial source of Cupric Chloride, (at least of spent etchant from the PCB industry), and thus can become a source of revenue. I qualify this heavily, as the EPA has trouble dealing with treating (hazarous) wastes as raw materials for other processes. Rudy Sedlak RD Chemical Company ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################