[kingsyaoran]

Hello. I am Nikos from Greece and i don't know if it is the right section to post to but plz forgive me cause i don't know much about chemistry.
Well, recently i have bought an animation cel (celluloid (cellulose acetate). My main problem that concerns an expert like you is that is smells like vinegar when i smell at the cel. I did a little research and it seems that's what happens when the cellulose acetate begins to get destroyed by time.
This particular cel seems to have been wet and dried, cause i can tell from the sheet quality. It's like taking a napkin and weting it and then drying it, it becomes a bit shrinked with wrinkles.
This cel has been drawn from the front and painted from behind.
So my question is: can i do anything to repair it? or get rid of the INTENSE vinegar smell or help it not deteriorate any  more? I am pretty terrified, so i thought only an expert could help me.
I am in your debt,
thank you.

[Borek]

What the animation cel is?

[kingsyaoran]

It's a celluloid made of  cellulose acetate. All are produced by treating the natural plant product cellulose with some kind of acid, changing its chemical structure and allowing it to be melted and then turned into transparent sheets for use in photographic film, microfilm/microfiche, or, as we have come to know, animation “cels.”
They print the lines of the sketch on 1 side of the celluloid and they turn it over and paint with acrylic paint the celluloid from the other side of it.
My problem is that the cel has started smelling like vinegar which means:
All of these materials, a variety of online sources confirm, have the odd property of remaining stable for long periods of time, then rapidly deteriorating in a way that not only destroys the images printed or painted on them, but also the materials stored in their vicinity. This is because the most serious aspect of the reaction is the release of the acid used to treat the cellulose. That’s nitric acid in the case of nitrate film/cels, and acetic acid (aka “vinegar”) in the case of acetate-based film/cels. Once the reaction begins, the free acid causes the molecules it contacts to break down, releasing more acid. This can take a long time to occur in a way that is detectable, as the reaction typically occurs inside the cel sheet, and only gradually travels to its surfaces. When this happens, the first symptom is a distinct chemical smell that resembles strong vinegar.

This is all i know about this ;( i know it's not much but i hope you know something more than me.

[Borek]

Ok, so these are just transparent sheets made of cellulose acetate (for reference: http://en.wikipedia.org/wiki/Cel).

No idea what can be done, but I guess if the problem is known (as you have described it), those involved in antiques restoration must have some methods. As far as I know, none of the regulars works in the trade.

If - as your description seems to be suggesting - it is an autocatalytic process, that is speed up by the created acetic acid, it should be possible to slow it down just by ventilating the cels and keeping them in the cold.