If I understood correctly what you wrote, you 
suggest that he puts his cels in an "Ordner" - 
don't know the word in English, I'm French... - 
but celbooks are "acid-free", so you're 
absolutely sure that nothing will attack your 
precious cels, while you don't know the making 
process for your "Ordner"... Maybe it won't make 
any difference, but it's a risk I would never 
take...