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September 2014
Issue: June 1, 2007

WHITE PAPER: COMBATING 'VINEGAR SYNDROME' IN FILM SOUNDTRACKS

By: Thom Piper & Michele Winn
It doesn't take much training to identify Vinegar Syndrome problems.  With a threshold of smell for vinegar of just 10 parts per million, the evidence is obvious. But using your nose to identify this invisible foe of sound preservation is neither safe nor efficient. Whether you have a vast collection or a small personal archive, the problems and the solutions are the same.

Vinegar Syndrome is the layman's term for a complex chemical reaction that occurs in acetate-based film stocks, causing them to decompose. As the acetate film breaks down it releases water and acetic acid (vinegar). This decomposition affects both image and magnetic sound films, but not equally. The magnetic oxide on the sound film actually accelerates the deterioration process. This catalyzing effect escalates the problem to significant proportions. One 1,000-foot reel of 35mm acetate film can generate up to 250 teaspoons of vinegar. That's over a quart! And sound elements as "young" as the '70s are generating gallons of the stuff!

Another side effect of acetate degradation is the release of plasticizer.  Plasticizer is the component in magnetic oxide that allows the magnetic particles to orient themselves during the recording process. As the film begins to decompose, the plasticizer appears as a thick white powder on the surface of the film. During a transfer this plasticizer builds up on the sound head, causing loss of contact and a muffled, dull transfer.

Chace Audio has developed an entire suite of services for the recovery and preservation of magnetic sound films and tapes suffering from Vinegar Syndrome. Spearheaded by film preservation manager Thom Piper, a 40-year veteran of motion picture sound, the Chace Film Prep Department has been designed to safely and effectively handle problematic sound film and tape.  Thom is assisted by film prep manager Michele Winn, a master's graduate in Film Archiving from the University of East Anglia. Thom and Michele ensure that the integrity of Chace processes meet the proper requirements for history, handling and archival practice.

To abate this tidal wave of vinegar, Chace has created proprietary instruments and solutions to aid in the transfer and restoration process.  For reels suffering from mold or mildew growth, the "Stinkerator" cabinet uses UV-light technology to inhibit and neutralize growth. The  "Stinkerator" also safely reduces the vinegar smell from the elements prior to handling by Chace technicians. A set of burnishing bars is also frequently used to reduce plasticizer build up and other soft emulsion problems. But perhaps the singular mechanical achievement is the Multi-function Magnetic Film Cleaning Machine (MFCM).

MFCM is a machine designed to mechanically automate several processes needed to prepare magnetic sound film for transfer. The unit can remove excessive dust and plasticizer in one automated process. This replaces what often took 40 hours of manual hand cleaning.

When emulsions are too soft or plasticizer build-up too excessive, making an efficient high quality transfer is very difficult. To solve the problems of head clogs or build-up, both of which cause loss of high frequency and dull transfers, Chace developed ThomSlick, a transfer assist product.

ThomSlick is an anti-friction lubricant that allows the soft emulsions and plasticizer laden films to pass over the sound heads without clogging. This allows for transfers in one pass as opposed to the time consuming "stop and start" transfer with frequent head cleaning.

The "anti-friction" properties of ThomSlick were particularly important during the restoration of The Diary of Anne Frank (1959). The 35mm 4-track stereo magnetic sound film had sections with advance stages of vinegar syndrome. The problem was so severe that in a few areas the magnetic oxide had separated from the acetate base and was literally hanging off the film. The small amount of friction created by the play head on this loose mag emulsion caused an unsatisfactory "chatter" or "screeching" quality to the audio. It was simply not usable. After the application of ThomSlick, the mag slid over the play head without any difficulties.

More than just an unpleasant smell, Vinegar Syndrome brings many potential health risks. Exposure to acids and possible acid contact with moisture in the body (nose, mouth, throat, lungs and even sweaty hands) can cause irritation or illness. Safety precautions to ensure the health of technicians include air filtration and purification in addition to the requisite goggles and breathing apparatus.

It is important to note that once a reel of film has begun to give off a vinegar odor, the film should be separated from any unaffected reels.  There is solid evidence to indicate that reels with vinegar syndrome can contaminate unaffected reels, thus spreading the problem. Once the material has been isolated, plans need to be made for the preservation of the deteriorating film. Though migration strategies vary widely, it cannot be emphasized too strongly that a proactive approach will save time, money and result in a superior quality restoration.

Since it is dangerous to test for vinegar with the nose, modern science has come up with an ingenious method to test for acid levels in collections. Developed by Image Permanence Institute, A-D strips are small paper strips placed in film cans that change color from blue to yellow to indicate the percent of vinegar. A-D strips are an excellent method to prioritize a Vinegar Syndrome affected collection.

Another invention that assists in prolonging element life are acid-scavengers called Molecular Sieves. These little packets of desiccants fit in the container with the reel to absorb the acid and retard the deterioration process. Available from Kodak, these sieves need to be used in a well-planned program, as they are not inexpensive.

A final and very cost effective solution for any size collection is to keep the sound elements stored in an area of moderately low, stable temperatures and humidity. While top archival practice recommends 40 degrees F and 50 percent relative humidity, a temperature of 68 degrees F, if it remains constant, can be beneficial. For really small amounts of film even an old refrigerator could be an effective short-term solution.

Whatever you choose to do, know that even a modest effort can have a positive result. When a Vinegar Syndrome problem presents itself, seek the assistance of professionals. Their training and expertise will ensure the necessary resources and safe handling to address this stinky problem.