Here is the best example I've seen that acetate tape's outgassing is 
absorbed by the cardboard box. Presumably the brown areas of the box 
are more acidic than the white areas, but I'm not really able to test 
that.
See: 
http://richardhess.com/notes/2006/10/16/acetate-tape-buffered-by-cardboard-box/ 
Richard L. Hess                   email: richard@xxxxxxxxxxxxxxx
Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.