I don't mean curling, like a roll, I mean curving along the length. (see below) I tried putting some heavy books on them for a few days when I was out of town, but it didn't do anything. When I do my scans, they need to be flat, but the center part of the negatives seem to be closer to the scanner bed and that's making a weird pattern in the middle. You can't see it so much on web-sized images, but for pics I want to print out, it's noticeable. Any thoughts?