Dear T.G.Yee Your readings are nothing special. As a matter of fact it is a normal behaviour for me that in the first time of a SIR test the resistance encreases in the beginning. As you continue the test ( 1000h ) you will see, that the resistance will start to drop and level later on. For a descriptive model to evaluate the asimptotic value you may use the sum of two e-functions. However, after 1000h your resistance redings should be stable enough to have no necessity for any modelling. Best regards Guenter Grossmann ( Still on the net since the unsubscribe didn't work ) ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################