Film Storage White Paper
Keeping Cool and Dry: A New Emphasis in Film Preservation
Redefining Preservation Task Force
(published August 1994)
Supporting Document A
Just as film itself has a history, so does film preservation. Today the National
Film Preservation Board is suggesting that our national preservation policy change
to reflect new technical knowledge about film decay. Research shows that film
needs better storage to survive, and that film in all stages of decay can have
a longer useful life with small improvements to its environment.
Our new policy should broaden the definition of preservation beyond its traditional
meaning of copying old film stocks to newer ones. It should view preservation
as a whole film enterprise, integrating previously separate issues of storage,
access, and selective restoration into a coherent, cost-effective approach.
The other purpose of whole film preservation is to develop a balanced use of
resources to save films in all formats and types in large archives and small
Film long ago ceased to be only for the movie theater; as film technology
became simpler and more accessible, it entered many arenas of education, industry,
documentation, and personal expression. Our challenge now is to appreciate
the fullness of film's variety, to locate and consolidate important fiction
and nonfiction films, and to prevent their further decay. The reward will be
more films for ourselves and future generations to study and enjoy.
The New Film Preservation Challenge
Current realities in film preservation have been shaped by the history of film
itself. From the 1890s to 1950 most professional cinema films (35mm format) were
made on cellulose nitrate plastic supports. Nitrate base film can become chemically
unstable, and many films that were stored in unfavorable conditions deteriorated
beyond use before they could be copied. The focus of preservation activities
came to be a systematic program of nitrate duplication as a preemptive measure,
before deterioration occurred. The goal of copying all nitrate was a rallying
point for preservation, and in some collections it was attained. Nationwide,
however, the rising costs of duplication soon outstripped available resources,
and it became clear that the scale of the nitrate problem was far too large to
deal with in that way.
When manufacture of nitrate film ended, two far-reaching innovations in film
technology occurred almost simultaneously. One was the replacement of nitrate
with nonflammable cellulose acetate plastic film support. Based on the (now
obsolete) accelerated aging tests of the day, film manufacturers announced
that safety films had far superior permanence over nitrate films. Attitudes
toward preservation were shaped by the conviction that acetate stock was permanent,
while nitrate was not. We now know that acetate and nitrate both share a tendency
to degrade; in fact, in some collections, the losses from acetate decomposition
are greater than from nitrate. Nature does not distinguish much between cellulose
nitrate and cellulose acetate when it comes to deterioration.
The second key innovation of the early 1950s was the introduction of chromogenic
color motion picture stocks, to replace the cumbersome Technicolor process
of the 1930s and 1940s. Audiences and cinematographers embraced color with
thoroughgoing and deep affection, so that few films after 1960 were made in
black and white. Unfortunately, the use of color introduced a tremendous new
problem of rapid color fading. The instability of organic color dyes, like
the decomposition of nitrate and acetate film base, results from a chemical
process which can be speeded up or slowed by the temperature and humidity of
the storage environment. Warm-and-humid conditions accelerate the rates of
fading and decomposition, while cool-and-dry conditions greatly slow the reactions.
The focus on nitrate and on duplication that has dominated film preservation
efforts does not confront the current realities of unstable safety stock and
color dyes. A rising tide of deterioration is flowing through film collections,
touching the smaller and medium-sized institutions most acutely. The short
life expectancies which once were thought to be only a problem for nitrate
now face nearly all films, because almost every film is either on nitrate or
acetate base, or else is in color. Today's color is more stable than earlier
emulsions, but it still has a short life in archival terms, unless it is stored
Prevention Should Be New Preservation Policy Emphasis
The starting point for policy change is to recognize a number of unpleasant facts.
One is the sheer size of the task. There are enormous quantities of films in
established film archives, and perhaps even larger amounts in other kinds of
collections and institutions. The huge volumes of film mean that massive efforts
would be required to address the problem through preemptive copying. Film archives
face shrinking budgets for preservation. Resources are diminished not only by
rising duplication costs, but also by greater demands that films be accessible.
Some collections have no funds at all for preservation copying.
The goal in film preservation is to extend the useful life of collection
materials so that they remain accessible to future generations. The problem
is to maximize each preservation dollar. Moreover, it is often not enough just
to understand how to improve the care of collections; the benefits of preservation
actions taken now must be communicated to funding agencies and somehow quantified
in order to lay claim to scarce resources. This has been a source of great
difficulty for film archives because so much of their work is preventive, rather
than remedial, in nature. The benefits of such work are difficult to quantify
in terms of dollars-and- cents or years of extended life.
Take an analogy from health care: Preventive medicine (regular checkups,
immunization, etc.) is very cost effective, because when conditions are diagnosed
early they are less costly to treat and involve fewer complications. Still,
there remains a reluctance to endorse a new preventive medicine emphasis because
the traditional late treatment pattern is already so expensive. Only with thoughtful
analysis and a long-term view does the value of prevention become clear.
The film preservation equivalent of preventive medicine is the collection
storage environment. Making original films last longer will reduce the need
for emergency duplication and will buy time for collections. In the future,
film will be reproduced and distributed by a host of new technologies, some
now available and some as yet undreamed of. The key to access in the future
is to preserve the original long enough to be converted, restored, and distributed
in these new ways. Original films have the maximum image and sound quality,
and will be the best platform from which to create access copies in the future.
Digital restoration techniques will be a part of, but not a substitute for,
preservation of original film materials.
The major preservation problems which now occupy so much of our efforts -
degrading nitrate and acetate film base, color dye fading, audio and video
tape deterioration are all heavily dependent upon storage temperature and relative
humidity (RH). Both science and actual experience agree that temperature and
RH are the primary rate-controlling factors in such deterioration. Every treatise
on preservation and conservation advises that cooler and (within limits) drier
conditions are better for film.
Putting Research into Practice
With color fading and acetate degradation becoming all too evident in film collections,
research has turned to investigating these problems. The Image Permanence Institute,(Footnotes
1 and 2) Eastman Kodak Company (Footnote 3), and other laboratories around the
world have provided a fuller picture of deterioration behavior. Although the
role of temperature and moisture in governing the rate of decay has been acknowledged
in preservation science and practice for many decades, something profound has
only recently been brought to light: the actual quantitative relationships involved.
Over the last twenty years and especially within the last five a great deal
of laboratory work has been done to establish predictive models of deterioration
for dye fading (Footnote 4) and film base decomposition in nitrate and acetate.(Footnote
5) These models have shown just how long inherently unstable materials can
last under the right storage conditions. They also show the converse that the
wrong environment can doom collections to very short lifetimes. Deterioration
is always proceeding, sometimes faster, sometimes slower. It is now possible
to know, at least in a general way, how long it is reasonable to expect collections
to last in any plausible combination of temperature and RH conditions.
Helping Original Films To Last Longer
Recent advances in our understanding of film deterioration point the way to a
balanced and cost-effective strategy of improved storage and selective copying.
Research shows that even degraded film will last longer under cooler and drier
conditions. If film is stored properly from the beginning, life expectancies
measured in centuries are possible. A number of major film companies have installed
low-temperature storage vaults to protect their valuable film assets. The heart
of the new preservation approach is to understand and exploit the relationship
between storage conditions and film decay to the advantage, rather than the detriment,
of film collections.
Clearly it is time to broaden the scope of film preservation activities and
abandon a narrow focus where copying in anticipation of future decay claims
such a large share of funding and staff resources. Duplication and physical
restoration of films is a vital part of preservation. It should continue, but
as part of a balanced program that emphasizes prevention of decay through improved
storage. Duplication should be used selectively in cases where films are showing
signs of active deterioration, or where physical restoration is needed to make
The advantages of such a balanced whole film approach are lower costs and
greater useful life for all the films in collections. The costs of improved
storage can be considerable, but they are still far lower than any other preservation
option. Cold-storage vaults and major environmental control projects conjure
up an image of outrageous cost, but when a single feature-length film can cost
$40,000 to copy, prevention seems by far the better bargain. While major vault
construction is costly, it is also cost-effective for many large collections
when the value of the collection and the costs of duplication are considered.
For smaller collections, centralized, shared storage in large vaults is a viable
way to achieve long film lifetimes.
The new research in film deterioration shows that small, incremental changes
in storage conditions can result in considerable life extension for film collections.
Staff education and new approaches to environmental monitoring can help collections
with few resources to determine where such low-cost but still potent improvements
would be possible. In fact, much can be done to preserve films short of large
capital projects. The first steps are to understand how deterioration is affected
by temperature and RH, and to measure actual conditions. Considerable improvements
can then be made by small, simple steps such as lowering thermostats, shutting
off heat vents, relocating collection materials within a structure, etc. For
some small collections, household freezers can be a very successful storage
Because managers of film collections have become accustomed to thinking that
only grand projects and ideal conditions will make a difference, they have
lacked the incentives to make incremental improvements. There is a need for
better tools with which to evaluate storage environments in light of the new
understanding of deterioration behavior. Such tools might include simple electronic
monitors that sense temperature and RH and read out in film life, as well as
computerized analysis of environmental data that sums up a long period of temperature
and humidity readings into a single life-expectancy value. There is also a
need for improved techniques for monitoring the condition of films over time
so that archives can duplicate films or take other preservation measures when
Film must be managed like any other valuable, but finite, national resource.
We can no longer afford to have a narrow focus in film preservation, concentrating
on just one approach or one type of film. A new preservation policy must emphasize
education, prevention of decay, and closer integration with outreach activities
that make film accessible to a wider audience. This requires an educational initiative
to teach the theory and practice of preventive care, and new tools with which
to monitor and assess storage conditions. It will involve reexamination of both
the funding structures and the practices of film preservation, but it will result
in more films being available to us and to future generations.
-- Drafted by James Reilly (Image Permanence Institute), in collaboration with
the other members of the Redefining Preservation Task Force: Allen Daviau (American
Society of Cinematographers), Peter Gardiner (Warner Bros.), Stephen Gong (Pacific
Film Archive), Robert Heiber (Chace Productions), and William Murphy (National
Archives and Records Administration).
- P. Z. Adelstein, J. M. Reilly, D. W. Nishimura, and C. J. Erbland, "Stability
of Cellulose Ester Base Photographic Film: Part I Laboratory Testing Procedures," Journal
of Society of Motion Picture and Television Engineers, 101, 5:336-346,
- P. Z. Adelstein, J. M. Reilly, D. W. Nishimura, and C. J. Erbland, "Stability
of Cellulose Ester Base Photographic Film: Part II Practical Storage Considerations," Journal
of Society of Motion Picture and Television Engineers, 101, 5:347-353,
- A. Tulsi Ram, David F. Kopperl, Richard C. Sehlin, Stephanie Masaryk-Morris,
James L. Vincent, and Paige Miller, "The Effects and Prevention of the
Vinegar Syndrome," presentation at the IS&T 46th Annual Conference,
Boston, MA (May, 1993).
- Conservation of Photographs, Kodak Publication No. F-40 (Rochester,
Eastman Kodak Company, 1985).
- James M. Reilly, The IPI Storage Guide for Acetate Film (Rochester,
NY: Image Permanence Institute, 1993).