Until recently I worked in a lab here in Berlin. We wet monuted prints on Aluminiun using rice starch. Firstly the aluminium board was sanded well so that the starch can grip on the board. The print was placed wet on the board and flattened with a roll. Overnight it dried and was flat as a babys bottom. For me the nicest way of mounting a print. A bit expensive though. We made prints in the size of about 140x210 cm.
I have also mounted prints on mat board. Sometimes the mat board tore itself apart because the tension of the dried print was stronger than mat glueing.
Long, long ago I mounted dry prints, using glue, on mat board. Putting the glueon the board.
The mounted prints wanted to curl up as mentioned in a post before.
I framed the prints anyway because I had an exebihition. Everthing was fine and afterward when I removed the prints out of the frames, they were perfectly flat,unto this day over ten years later.
It works but can be frustating.
I am still working on optimising it.