I honestly don't know, but I doubt it.  
Especially the ones you can buy at the 100yen 
shop.  For some reason, I don't think that these 
things are generally made with that sort of 
thought in mind.  But for temporary storage, I 
really don't think it's going to hurt anything.  
When I run out of room in a cel book, I keep my 
new cels in one of those until I have time to get 
another.


Jennifer