In collecting cels, I've noticed that certain 
areas or colors on characters are more prone 
to line fading then others. For instance, I've 
found that areas of cels painted with warm 
colors (yellow, orange, brown) seem to have 
line fading much more often than areas 
painted with cool colors. A good example 
would be Miaka's hair and her brown school 
uniform. It's very rarely you can find a cel of her 
that DOESN'T have line fading somewhere, 
especially in her hair. The paint in her hair 
also seems to stick to sketches A LOT. Like... 
much more than the paint anywhere else. 

Now what I'm wondering is, DOES paint color, 
in fact, even though on the other side of the 
acetate, somehow effect what areas of a cel 
are going to fade quicker or easier?

Basically, I'd like to know guaranteed causes 
of line fading other than "the cel was exposed 
to too much light" etc etc. It's mostly out of 
curiousity, but it'd also help me to take even 
better care of my cels so that the lines don't 
fade in the future.  :)