I think i've posted on this board more today than 
in the past 5 months^^;;;!

Anyway...

I keep all my cels in cel bags...Except for a few 
groslly oversized ones that I'm having trouble 
finding cel bags fot -_-.

The ones that aren't in the cel bags always make 
me worry...but in the 4 years I've had them they 
haven't loss any line or paint quality.  Some of 
the ones in the bags however...Have lost some 
line quality.

BUT

I really think it's in the production quality of 
the cel that affects the outcome of your cels 
quality.  Like TOEI cels seem to always lose 
their line quality no matter what you do.  I 
think storage also plays an important role in the 
quality of your cels.  

My cels never see the light of day, unless I'm 
taking them out to look at them, or if I'm 
venting the cel bags.  All i do is open up the 
cel bags, take out the cel, look to see if it 
needs cleaning, & simply put it back in the bag.  
that gives it a chance to "air out" all the gases 
that may be trapped inside.  Then away they go 
back into the massive art portfolios I have them 
all stored in.  They're on a flat table in my 
dry, humid-free, & dark basement ^^.

I think it all boils down to how well you take 
care of your cels, as well as the quality of the 
cel as it was made for production.

As for the price tag residue...

I really couldn't give you any solid advice on 
that one. It all depends on the type of residue
(yeah...Sometimes there's different price tag 
residues^^;;;!).  If you want to use the safest 
liquid...I would used de-mineralized water.  Pour 
it on a clean, soft cloth, & gently wipe at the 
residue.  Don't saturate the cloth with water 
though.  You can try applying a bit more pressure 
if needed, but think of the cel in the terms of 
an egg shell...Too much pressure can cause 
damage^^;;!

I hope this helps =)!