[pure-silver] Re: Deteriorating movie film

At 09:19 PM 3/25/2008, you wrote:
I have just retrieved from storage a large box of 16mm movie film from the 1950s. Some is Kodachrome taken by my father, and some are black and white commercial copies from the US of various types of entertainment, such as cartoons, Charlie Chaplin, travelogues etc.
The box smells strongly of acetic acid, which I understand is the result of some breakdown of the films. Can anyone tell me if the two types of film are equally likely to deteriorate, or would there be a difference between the Kodachrome and the black and white commercial films? The colour of the Kodachrome looks very good. 

John Stockdale
All 16mm movie film ever made was on safety stock. If you do a google search for "vinegar syndrome" you will find a great deal of material on line. There were at least three variations of cellulose acetate stock used, some are more susceptible to decomposition than others but I don't remember exactly which are which at the moment. My memory is that the type of stock varied more with time period than with the kind of emulsion coated on it. As with nitrate stock the quality varies a lot with manufacturer. Evidently, Dupont stock tends to decompose more than Kodak. One artifact of the decomposition of the support is re-coloration of anti-halation dyes. These dyes are not removed from the back coating but are de-colorized by the sulfite in the developer and fixing baths. I am not certain if all motion picture film had this type of back coating. 

      A place to start is:
http://aic.stanford.edu/jaic/
      But there are many other sources of information.
AFAIK, like decomposition of cellulose nitrate film there is not much that can be done once the process begins. I would begin with smelling the film to see if you can determine which reels are the furthest gone and isolate them from the others. The only way to preserve the images is to copy them if he support is strong enough to withstand it. The affected film is likely to also show some physical signs such as cockling or edge frilling. 




--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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