Hi Sonia!

I actually had the same issue - I had a She-Ra 
cel and a Glimmer cel matted and shrinkwrapped.  
My main concerns were:  1)  storage 2) is that an 
acid-free matte??!! @_@;

I ended up removing them from the matte and 
putting them in cel bags in my book.  I did keep 
the mattes.   One of these days I may use them 
for something.  Fortunately, I was able to 
separate the laser copy background, the cel and 
the matte safely. I did it VERY slowly!  ^_^;  It 
was only a matter of removing some tape from the 
b/g and cel that fastened it to the matte.

I have tried shopping for acid-free mattes in the 
past (window shopping) and I have seen that they 
generally aren't that expensive. You can buy pre-
cut mattes for about 2-3$, or buy a sheet and 
have it cut to the dimensions you need.  I don't 
know exactly how much it costs, but I don't 
remember it being more than about $10 at Pearl in 
Boston.

jINx (^_^)