It has been pointed out by several of the Technet responders that many factors are involved in making a prepreg thickness determination. I would like to add that a standard testing procedure used by prepreg producers for determining the prepreg pressed thickness is to take multiple plies of prepreg (i.e., 10 sheets or so) press them under some standard condition of pressure and temperature and time and then measure with a micrometer the pressed thickness of the stack. Dividing that thickness number by number of plies of prepreg used in the test is usually the number that appears in the product data sheet for pressed thickness. Regards, Lyle Wallig ############################################################## 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 ##############################################################