Cels Forum

     For Matboard, I usually use Crescent Rag Mat.  Rag Mat 
is made out of cotton, not wood-based fibers, so it has the 
advantages of:
  brighter, whiter core
  will not yellow over time
  safer for your original cels

     You can still use regular wood-fiber(aka paper) based, 
100% acid free matboard, but if you want the better 
archival quality, use a cotton based matboard.  (The 
whiter core is the main reason I prefer it). 
     If you can't find Crescent Rag Mat, look for any 
cotton-based matboard.  It costs more than Regular 
wood-based matboard, but since I usually cut matboards 
myself, the cost difference isn't much.  But when you get it 
customed framed, sometimes the difference between the two 
materials can be $10-$20.
     I puchase Ragmat at Pearl, an art supply store, or at a 
wholesale store near my house called Valley Frame and 
Moulding.  (They charge 10Illegal seekore, with a minimum of 4 
sheets, since I'm not a wholesale person.)
     Average price:  about $8 or less per sheet