Well, I have tried to remove rice paper 
stubbornly stucked on one of my cels. It was all 
totally stuck and stubborn as I was, I tried 
removing every bit and pieces.

I guess I over-handled it with my bare hands + 
penknife and the paint turned slightly soft, as 
if it started squeezing out oil from the paint. 
Eeeks!

I stopped immediately and leave all my cels stuck 
on the rice paper without removing them now.

Bad experience. But one thing, leaving a cel too 
dry might also crack the paint. ^_^ So do 
everything in moderation... basically a try and 
error thing.