[Tig] Re Lifespan of different mediaformats

Carl Skaff carl at stopp.se
Sat Oct 29 19:41:09 BST 2011

Interesting to read that Camera Neg is ok for 50yrs... I just stumbled
accros an article that talked about very different timespans.


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

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*.

It is important to note that, yes, the Preservation Index is measured in
number of years, but as defined by the Image Permanence Institute, it is not
a fixed number. The PI is relative, since you seldom know how the previous
storage of a collection item has impacted its overall life expectancy. Take
a roll of film for example. Even new film stock is subject to a wide variety
of conditions on its way to permanent storage. Kodak makes it and stores it
under pretty good conditions, but then it is shipped by a truck through who
knows what kind of weather. Maybe it sits in an uncontrolled storage
warehouse for several days before it is shipped to a customer. Even under
cool office conditions, film would only last about 50 years before serious
degradation could occur, but stored at 25F and 30% relative humidity, you
can expect it to last 40 times longer than that – *2000 years*.

These numbers are relatively non-controversial, so we can take them as a
starting point.

(ND. I plan to die long before film, tape or data. So don't blame me when
the time comes and you can't play your ancestors wedding movies)

(Sent from mobile device)
*Carl Skaff*
Stopp Stockholm
Office +46 8 50 70 35 00

*Stockholm | Los Angeles | Linz*

More information about the Tig mailing list