Digital BW, The Print

> The wax paper is a vapor/atmospheric barrier.  DuPont Mylar sheet 
>would be best but VERY expensive.  It slows migration of chemicals 
>through the back...

Some years ago I used cheap cardboard in framing and put either wax paper or
aluminum foil between that and the interior materials.  I took them apart
after a number of years and found the acids had migrated right through the
wax paper, but not through the aluminum foil. 

Paul
www.PaulRoark.com