i have some old rolled up ( OOPS ! ) banquet photos that were stored in a tube before i got them
i asked a museum-friend the best way to get them flat and it was suggested that i make a water/humidity chamber
... get 2 trash cans, fill a trash can with water and suspend the print inside the 2nd trashcan which is inverted/
upside down inside the first trash can. the humidity from the water will slowly be absorbed into the prints and hydrate them.
sadly i have too many irons in the fire and never got a chance to follow through on the advice given to me,
but i talked to her again a few weeks ago and we talked about it again. i have one of these banquet prints
in a frame already, as it was given to me, so i never flattened the others. they are 12x24, some bigger, some smaller.
good luck getting the prints flat!
john