Film Deterioration Guide - gouvernementcna.public.lu/.../3_3_Tools_FIAFTC_FilmDeteriorationGuide_2002.pdf · In the final stages film congeals onto a solid block and then become a

Film Deterioration Guide


It is important that the film archive community uses the same terminology when referring to deterioration on film. The Technical Commission is producing a series of posters to help in the identification of these deterioration. This project is called Film Deterioration Guide. The first poster is about the Cellulose Nitrate Decay.


The first impression on the technical state of a film is made when we look at its reel. Rewinding the film we observe how it behaves. Looking closely at it with a magnifying lenses we gather Important information. The posters will have images covering these various levels of observation so that in case of doubt more than one situation is offered as example.


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Cellulose nitrate is an unstable polymer. Its decomposition starts when the polymer is manufactured and continues until total destruction of the film. Cellulose nitrate is highly flammable. Some cellulose nitrate survived for more than 100 years in quite good condition. Nitrate prints have an unique “look” and film archivists love it.


5 stages of Cellulose Nitrate decomposition: a. All starts with a “sweet” smell;

b. Slight discolouration of the plastic (film base);

c. Followed by the bleaching of the silver image;

d. The emulsion medium (gelatine) breaks down onto a viscous paste;

e. In the final stages film congeals onto a solid block and then become

a brownish powder.

(*) Up to the stage d film content can be recovered.


1 Structure of the poster, each category is displayed as: 1. Reel format 2. Reel on a rewinder plate 3. Detail of the deterioration 4. Film between plates on a rewinder 5. 3 frames in real size (1:1) 6. 10X magnification

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1 Image discolouration 1 The gases released by cellulose nitrate decomposition react with the silver forming the black and white image fading and bleaching this image. The first signs are a metallic shine followed by the yellowing of the Image.


Image discolouration 2

Image discolouration can reach drastic levels. Cellulose nitrate decomposition can release other chemicals (plasticizer) that will appear in the surfaces of the film as finely divided solid deposits.


1 Base discolouration

Chemical changes in the cellulose nitrate molecule modify the way it interacts with light making the film base no longer transparent. Base discolouration can go from yellow to dark brown with a variety of colours in between.


1 Emulsion breakdown 1 Gases released by cellulose nitrate decomposition react with moisture and form acids that react with the gelatine (emulsion medium) making it become liquid. In an initial stage of this deterioration film can still be saved.


In the last stages of decomposition cellulose nitrate film cannot be restored. Special personal protection equipment must be used to handle film in this stage of decomposition.


2. Cellulose Acetate(s) Decay


1 Base Limpness

Gelatine breakdown produce, In advanced stages, massive deterioration on film.



1 Base Limpness




1 Base Curling




1 Base Curling




1 Plasticizer Liquid Residues




1 Plasticizer Solid Residues



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Documents

Film Deterioration Guide - gouvernementcna.public.lu/.../3_3_Tools_FIAFTC_FilmDeteriorationGuide_2002.pdf · In the final stages film congeals onto a solid block and then become a