Yes, you add all the anions and report them as the equivalent of NaCl. Personally I have a problem with that, because some inorganics are worse in deteriorating products than others and reporting them as NaCl can be misleading. The method for calculating micrograms/cm2 is ok. Leo Roos ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################