Hi!  I bought some animation cels a while ago 
and had them professionally framed with museum 
grade glass and acid-free matting.  They have 
always been located in indirect light and away 
from heavy light sources yet they all experience 
some type of line fading (especially where the 
animators put colored paints over the lines).  
Does anyone have any suggestions as to how I 
could have avoided and remedy this (beside 
taking them out of the frames and putting them 
back in dark storage -they're already off the 
wall)?  Someone suggested that the glass 
protective coating could have worn out over time.

Thanks
     John