This 35mm dupe negative shrank and curled as the acetate base decayed.
Notice the curl present in the nitrate negatives still stored in flat paper sleeves, as well as the negative which has been removed from the album. Early nitrate roll films were manufactured without an anti-curl backing layer. The anti-curl layer, added in 1903, was a thin gelatin layer applied to the base side, which helped prevent this type of tight curl.
(Top) Here tinted 35mm nitrate film displays edgewave, a kind of distortion that may appear as spoking when wound on a reel. (Bottom) This 35mm nitrate film demonstrates brittleness and permanent distortion, symptoms of dimensional changes caused by nitrate base decay.
This 35mm tinted and stencil-colored film demonstrates spoking, a form of distortion that can result when a warped or curled film is stored loosely wound and stored at a low relative humidity.
This 35mm full-coat magnetic track shows heavy shrinkage and curl caused by advanced acetate base decay. Magnetic track elements are particularly susceptible to the problems associated with acetate base decay. It is believed that the iron oxide present in magnetic tracks acts as a catalyst for deacetylation of the acetate support, hastening the onset and progression of acetate support decay.
What it is and what causes itDistortion is caused by uneven shrinkage across a film’s dimensions, and manifests itself as warp or curl in the film. Distortion may be caused by differences in shrinkage between the support and gelatin binder of the film, or between different locations on the film, as these different locations are exposed to relative humidity in the environment.Distortion can be temporary, in cases where a film has been moved from one environment to another. Long-term storage of a film in extremely dry conditions can result in permanent distortion. Dramatic shrinkage caused by acetate or nitrate decay will also result in permanent distortion of the film. For motion picture film, permanent curl, when accompanied by embrittlement, may make the film difficult or impossible to duplicate with a printer or scanner. |
What you can doTemporary curl is the result of film acclimatizing to the temperature and relative humidity of a new environment. The warp will disappear when the film returns to its proper storage environment.Permanent curl is irreversible, however, and can only be prevented by storing the film at cold or frozen and moderately dry conditions. |
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