I have never stuck ATG underneath the bottom matboard before but I have noticed that with framing work that I have done in the past, the matboarad has started to "rise" up a little bit and creates an undesirable void. I am contemplating placing ATG underneath the bottom matboard to alleviate this problem. It will then also be stuck to the inkjet photo underneath since the matboard overlaps the image area by 1/4". Obviously not an archival process and one which cannot be reversed bit what else can I do to prevent the matboard from rising? Specs: 4 ply rag & paper mats, inkjet photos drymounted with vacuum press. Thanks for any help. BTW; Searched for answers to this specific problem but ......... notta.