^_^

The final word is that you can back your cel with 
essentially anything that doesn't leech dye (i.e. 
anything that isn't dyed). Rice paper, tissue 
paper, even normal 'cel paper' is okay.. I back my 
cels with tissue paper - I choose buffered AF 
because I keep my douga within the same bag (and I 
think douga are acidic, so the buffering is really 
to lengthen the lifespan of the paper, not the 
cel). Anyway, there's a little more information 
and a few links for backing tissue (I hadn't added 
rice paper sites yet) in my still-being-wrought 
QND guide to 
Cel Supplies.

^_-