My search has brought me to some reading that is aimed at the audio/video archive community. The
recording medium in the 30’s thru the 50’s were based on Cellulose nitrate or Nitrocellulose. The
recording discs were nitrocellulose lacquer and the film was nitrocellulose based also. As a plasticizer
camphor or synthetic camphor was added to the cellulose nitrate so the disks would be soft enough to
be cut and so the film would be flexible enough to run thru the projectors.
The Trico patents I’ve looked at suggest that the piston seals used by them in the 30’s thru the 50’s
used cellulose nitrate impregnated fabric as the flexible plastic. If that’s correct, then this would give
reason to why the seals appear stiff and dried out once they are cleaned sixty or seventy years later. The
camphor used as a plasticizer in the compound leaches out over time and the nitrocellulose shrinks and
becomes brittle.
Film Archivists place vintage films in a sealed container with synthetic camphor to soften the film,
which they are then able to run thru a projector in order to make a digital preservation copy.
So my thoughts are this; if after cleaning the piston seals they were placed in a closed container with
camphor would that re-plasticize the seal making it soft enough to seal the vacuum once again?????
Denny Graham
Sandwich, IL
