I had several cels framed for a few months, but 
didn't use the UV-protectant glass.  It really 
does make a difference.  The lines weren't totally 
faded, but they weren't exactly as dark as they 
were at the beginning, either.  I replaced all my 
glass with UV-resistant glass about a year ago, 
and hung them in an alcove in my room which 
doesn't get much light.  It has preserved the cels 
much more effectively than before.  

It still isn't a perfect method, though.  If you 
want to completely protect a cel, I suggest 
keeping it in a cel book.  That's what I do now 
with all my nicest cels.  But if you really want 
to go ahead with framing, I strongly recommend 
making the investment in UV-resistant glass.  
You'll be glad you did later.  Besides, what's a 
few bucks when it comes to preserving your 
favorite cels (which more than likely cost fifty 
times as much as the glass)?

Incidentally, I bought my UV-protectant glass at 
Michaels, which has really good prices (at least, 
I think so).  They cut the glass according to your 
size specifications, but be careful when handling 
them!  They can be very sharp around the edges.  I 
suggest wearing gloves unless you don't mind 
bleeding all over your cels.  I learned that one 
the hard way. 

Looks like my two cents turned out to be more like 
twenty cents.  Good luck with your framing 
project!

~Anne