Since you are only seeing this on the outside panels in the stack, it would indicate that your heat rise in these panels is significantly faster than the panels in the middle of the stack, meaning that the resin sets up in these panels before all of the air is evacuated. Measure your heat rise on both the top and bottom panels and on the middle panel; the heat rise rate and the lagging material may need to be adjusted to reduce the heat rise on the outside panels. You also might specify a certain range for your heat rise rate - we always looked at 190F-300F rather than ambient to whatever the max temp was, since that was more of a critical range (it's where the resin flows and sets up). You may wish to try "PACOPAD" from Paper Corp. of the United States - call 212/337-5539 for your local supplier. We use Pacoform #5500-10 here. I have also used silicone rubber sheets with some success, but I can't remember where I bought them. I also never had much success with using 7628 for filling anything bu 1oz plane layers. I personally would never try to fill 2 or 3 oz with anything thicker than 1080 - probably 2 plies next to the plane layers, and then the 7628. Hope it helps. Fred J. >>> Afri Singh <[log in to unmask]> 01/22/98 10:39pm >>> Can anyone shed some light on a problem i am having in my lam dept. We are getting pockets of air (bubbles) trapped in low pressure areas towards the middle of the panel Seen only on the top or bottom panel of each book This only happens on cores with 2-3 oz cu. So far we have tried heat rise 12 -16 F /min b-stage with more resin- we are using 7628 only vacume assist press and hydrolic low pressure vs high no kiss cycle flatness of plates not able to modify the pettern thank you for any suggestions ############################################################## 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 ############################################################## ############################################################## 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 ##############################################################