8mm Forum: Curling Pathescope Film

This is topic Curling Pathescope Film in forum 9.5mm Forum at 8mm Forum.

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Posted by Paul Adsett (Member # 25) on August 31, 2017, 10:54 AM:

I have noticed that Pathescope film prints have amazing mechanical 'memory' properties. Leave a print threaded on the projector for a few days and the film will assume the shape of the film path! Even more noticeable is the spring-like memory properties of the Baby cassette films, which acts just like a clock spring and is a bear to handle! I wonder why and how Pathescope treated the films to get it this way.

Posted by Maurice Leakey (Member # 916) on September 02, 2017, 11:32 AM:

It may be due to the fact that Pathescope films were printed on cellulose acetate base, a factor determining the longevity of their 9.5mm films.
Care must be taken not to store them in too dry an atmosphere which may cause cupping due to shrinkage of the base material.
I realise that this does not necessarily answer Paul's comment, but I thought it may be of interest.

Posted by Janice Glesser (Member # 2758) on September 02, 2017, 12:39 PM:

The chemical properties and dryness of the film most likely does contribute to it's spring-like memory. But being encased in those little Baby cassettes for 80+ years is probably the main factor. It's amazing they run through a projector at all. As you mention Maurice... the cupping can inhibit even focusing and the twisting makes splicing and editing very challenging. However, I get a feeling of wonder every time I project one of these films.

[ September 02, 2017, 02:13 PM: Message edited by: Janice Glesser ]

Posted by Clinton Hunt (Member # 2072) on September 02, 2017, 07:01 PM:

This doesn't answer why they curl but ... a while ago I decided to put a few of the cartridge cassettes onto a normal reel so I could project them on my Specto ... and as Janice said ... what a nightmare,really curly at the ends but I persisted and joined them,they project well.

Posted by Ken Finch (Member # 2768) on September 04, 2017, 02:54 PM:

Oh yes Clinton, it is a nightmare. Many years ago I agreed to join some family films together to be shown at the birthday celebration of someones 90 year old granny. When receiving the films I discovered they were all in 30ft cassettes, 900ft of them. As you say all like watch springs and difficult to join. No tape splices in those days. It was very hard to keep them flat on the splicer. Ken Finch [Razz]

Posted by Dino Everette (Member # 1378) on October 08, 2017, 10:43 PM:

My opinion is that it is a combination of the fact that old films experience shrinkage, and that they are inside metal cassettes, which will amplify the heat on the film which has been stored in environments that switch from cold to hot conditions. I have seen hundreds of 16mm prints that have been stored in warmer conditions over the years and they exhibit the same sort of "permanent" curl...Basically storing films in cans in houses that have varying temperatures throughout the years can be risky, as the metal cans amplify the changes...At work I once came across the greatest single longterm test case ever....It was a box of 35mm trailers that came straight from the lab in 1973 to the person's house. The person stuck the box in their closet and it sat there for 45 years until we picked it up at the archive. Inside the box were 12 copies of a trailer, 11 of which were in metal cans, and one was in a cardboard box..The 11 were all terribly deteriorated with extreme vinegar syndrome, brittle and shrunken, and the one in the box was in perfect condition...Metal is great for archives that store films in the cold, but terrible for the home, which may have large temperature changes throughout the year...The boxes breathe in such an environment where the metal cans just work harder to ruin the film by increasing the change in temperature. If the house is 75 degrees, it is probably 80+ inside the can, or if the house is 60 it is probably 55- in the can...in the archive it is the opposite because the boxes can easily develop mold or problems if the air quality is not kept dry...

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