Cels Forum

Cels most certainly can get stuck to pencil sketches after you 
get them if they are stored together. One way to prevent this is to 
slip a very thin piece of plastic, much like saran wrap, between the two 
while you store it. Never stack things on top of cels, because the weight pressing 
the cel to the sketch can cause the paint to adhere. 
The type of paint used for cels is a particular type of water-based acrylic which 
is very easy to clean while wet, but is very succeptable to moisture during storage.
The paint sticks more easily to  paper than to the acetate of the cel, so if the cel is 
exposed to moisture and/or pressure, the paint is in danger of adhering to the paper it contacts. 
If the paint adheres more strongly to the paper than to the rest of the paint around it, then if you 
try to separate the paper from the cel, then the paint will stay with the paper!
By heating the paper with a blow-drier, I suppose the paint becomes less likely to flake 
and therefore easier to separate from the paper.
The best way to preserve a cel is to frame it with acid-free products 
and UV-protective glass. The lines which the cel-painters use as guides are 
essentially xeroxed on and are very succeptable to sunlight and other light damage,
which results in fading. 
Hope this helps.