Know Your Enemy: Damage and Decomposition

BIGOURDAN Jean-Louis, COFFEY Liz, SWANSON Dwight. Know Your Enemy: Damage and Decomposition. In Film Forever. The Home Film Preservation Guide [Online]. [Accessed April 12th 2007]. Available at <http://filmforever.org>

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3.4 CHEMICAL DAMAGE

Film components such as film supports (e.g., nitrate and acetate) and color dyes are inherently subject to chemical deterioration.

3.41 Nitrate Decomposition
Cellulose nitrate film base is prone to chemical decay over time. The condition nitrate films are in today is a direct result of the conditions under which they were stored, as well as how they were manufactured.

Nitrate decay is described in terms of 5 specific stages. These descriptive stages are a widely recognized standard.

Stage 1: Film has an amber discoloration with fading of the image. Faint noxious odor. Rust ring may form on inside of metal film cans.
Stage 2: Emulsion becomes adhesive and the film tends to stick together during unrolling. Faint noxious odor.
Stage 3: Portions of the film are soft, contain gas bubbles, and emit a noxious odor.
Stage 4: Entire film is soft and welded into a single mass, the surface may be covered with viscous froth, and a strong noxious odor is given off.
Stage 5: Film mass degenerates partially or entirely into a shock sensitive brownish acrid powder.

3.42 Acetate Decomposition: Vinegar Syndrome
Acetate base film is subject to the so-called vinegar syndrome. The term 'vinegar syndrome' is taken from the distinct odor that is given off by deteriorating acetate film. Vinegar syndrome results from a chemical reaction that takes place at the molecular level that can cause serious and irreparable damage to film. When combined with moisture, heat, and acids, the plastic support in the film begins to release acetic acid. The process is an autocatalytic one, meaning that once the degradation begins it starts to 'feed upon itself' and the deterioration process begins to snowball. When film reaches its autocatalytic point the acetic acid released by the film grows exponentially, and with it the potential problems for the film. Climate is an important determining factor in the deterioration because humidity affects the amount of water absorbed by the film and heat supplies energy for the chemical reactions. Even more important is the "micro-environment," a term used to describe the conditions inside the film can. Vinegar syndrome appears to be contagious, so any film suffering from it should be stored apart from "healthy" reels.

The vinegar smell is the most obvious indicator of decaying acetate film, but it is by no means the only one. The condition of the film can be evaluated by using acid detector strips (e.g., IPI’s A-D Strips); this approach provides an objective way to determine the state of preservation of the materials and their needs to be further stabilized. White powder on the edges of the film may indicate plasticizers loss. Because of the molecular breakdown of the plastic base, in advanced stages of deterioration the film becomes brittle and shrunken. Films with shrinkage of more than 1% could be damaged by projector mechanisms, so should not be projected.
There are techniques for re-dimensioning film (restoring it to a less-shrunken state), but these are temporary measures that can permanently damage the film and should only be done in a lab situation as a last-ditch method to enable a new negative or print to be made.

Acetate Decomposition—Advanced Stages of Decay
The typical pattern for acetate decay is:

1. Vinegar odor
2. Shrinkage
3. Cupping: the film retains a curve. It will not lie flat, but instead appears wavy.
4. Crazing: the emulsion cracks and the image appears as a crazy mosaic.
5. Appearance of white powder on edges (from binder deterioration, this is the plasticizer separating from the film).
6. Film becomes square on reel.
7. Film is no longer flexible and the emulsion flakes off from the base.

3.43 Color Fading and Decomposition
Color fading and other forms of chemical decomposition are usually the results of inherent problems in the manufacturing of the film, bad processing or poor storage conditions over the years. Generally there is nothing that can be done to reverse the process of color fade. However, you can stop further damage to the film by moving it into good storage conditions.

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Dublin Core analysis

TITLE : KNOW YOUR ENEMY: DAMAGE AND DECOMPOSITION

CREATOR : BIGOURDAN Jean-Louis, COFFEY Liz, SWANSON Dwight

SUBJECT : biological deterioration, chemical deterioration, mechanical deterioration

DESCRIPTION :
3.1 DETERMINING AGE
3.2 MECHANICAL DAMAGE
3.21 Tears
3.22 Perforation Damage
3.23 Scratches
3.3 BIOLOGICAL DAMAGE: MOLD, MILDEW, FUNGI
3.4 CHEMICAL DAMAGE
3.41 Nitrate
3.42 Acetate: Vinegar Syndrome
3.43 Color Fade

PUBLISHER : Film Forever

CONTRIBUTOR : Bob Brodsky and Toni Treadway (Editors)

David Cleveland and Robin Williams, East Anglian Film Archive
Don Radovich (Photographer)

DATE : 2002-11-19

TYPE : text

FORMAT : html

IDENTIFIER : http://filmforever.org

SOURCE : BIGOURDAN Jean-Louis, COFFEY Liz, SWANSON Dwight. The Home Film Preservation Guide [Online]. [Accessed April 12th 2007]. Available at <http://filmforever.org>

LANGUAGE : En

RELATION : Sponsored by Association of Moving Image Archivists (AMIA)

COVERAGE : International

RIGHTS :