Thank you very much. Since I'm moving soon, a drymount press isn't an option. So I'm going to try just blotting one off, hang it by a corner to dry, find the archival equivalent of contact cement, and glue one down on a wood panel as a trial. Then put a few hundred pounds of books and tools on top for a few days. Because of the weight of fiber paper, it's not just the curl, it's the way it wants to snap back into that curl that's the problem. There ARE glues and cements that will hold anything to anything, the hard part will be finding something non acidic that won't eat up the paper from the back over time.
This is worth a try: It will never come off w/ this stuff, but I need to call around and see if it's acid free.