Cels With Black Paint...

This has been bothering me for awhile now...
I own at least 2 cels that are in great condition, but the back of the cel is painted in black right over the colored paint. From the front you wouldn't even know because the black paint on the back doesn't show through.
but I'd still like to know if there is a reason why they paint over everything in black on certain cels...
Just curious...does anyone else have a cel like this?
Thanks!! ^__^

These are what are referred to as "black-backed" cels. Generally, these cels are painted black on the back because they will be backlit or to prevent the background or back cel layer from showing through when filmed. It's not an uncommon thing to see. I had an Armitage cel that was painted like this and my opening cel of Kei from DPF is painted this way as well. Nothing to worry about :)

Ohhhhhhh! Okay!
I thought it was something like that, but I wasn't sure...makes sense.
Thank you ^_^

Oh...I have 2 cels that are like that too...I tought that they may be fake, since 99% of my cels don't have black paint in the back....Thank you for the answer :)

It's often frustrating if you have a black-backed cel with matching douga, many times the douga is stuck because of the shear mass of paint. Black and Red paint seems to be the worst for sticking to dougas- is this true or am I just imagining it?