my own experience was at variance

Film There was a time, not too long ago, when I thought I'd be able get a job in a film archive. Like all of the job ideas you have when you're young (I was thirty) I realised that my own experience was at variance to the requirements of the of the job. But that doesn't mean I don't still keep myself informed of new developments.

One of the key archives is at The Library of Congress which is responsible for over six million audio-visual items, many of which are unique. Ken Weissman, Supervisor of the Library's Film Preservation Laboratory talks at some length and fascinating detail about their work which is generally about numbers. Here he is on how long they'll be able to store the work for future generations:

"Several years ago, the Image Permanence Institute developed the concept of Preservation Index (PI). This is a measure of how ambient temperature and relative humidity affect decay, and is expressed in years.

We have differing conditions depending upon the materials stored in them and their use. Our nitrate film is stored at 39 degrees Fahrenheit, with 30% relative humidity. This equates to a Preservation Index of 655 years.

For non-nitrate film preservation masters (also known as “safety film”), we store at 25 degrees Fahrenheit, 30% relative humidity, for a PI of 2125 years. All of our new film preservation masters go into this storage environment.

The remainder of our collection includes magnetic tapes of all types and flavors, both audio and video — Edison cylinders, wire recordings, metal stampers, etc. You name it, we probably have it. These are stored at 45 degrees Fahrenheit, 30% relative humidity, for a PI of 429 years, and in some cases, at 50 degrees, 30% relative humidity, for a PI of 244 years.

He also writes at some length about the difference between digital and hard copy storage, like me coming down on the side of the latter, generally because of the logistics of storing and shifting the massive data files required and their in-built ephemera [via].