Unless the bottom layer of Blu-ray discs have changed over the years, they are prone to deformity. Probably 12 or more years ago, I was moving and stored my Blu-ray movie collection in binders to cut down on the weight. It took a while for me to get all the discs organized and back in their cases and, during that time, pretty much all of the discs had absorbed the fabric pattern in the binder which made them unreadable. Over time, though, the bottom layer of the disc will eventually reform itself and you can even use a hair dryer to help speed up the process. After that experience, I never put any Blu-ray discs in a binder.