Is there a way to clear away unnecessary paint 
from a cel? I recently bought a cel that comes 
with a dark colored background. But because the 
cel and the background had been placed together 
for such a long time, some of the brown color 
from the background actually got stuck to the 
back of the cel. And now, when I turn over my 
cel, there are actually specks of brown colored 
paint all over the back of my cel. When I look at 
the front of the cel closely, I can actually see 
some of the brown paint through the face. So is 
there a way to clean the paint off? Or should I 
just leave it there?

One more thing. How do I clean off dust or dirt 
or anything other small particles from the no-
paint area of the cel sheet without hurting the 
cel?