ISO 18911:2000

Imaging materials - Processed safety photographic films - Storage practices

Matériaux pour image — Films photographiques de sécurité traités — Techniques d'archivage

General Information

• Status: Withdrawn
• Publication Date: 15-Nov-2000
• Withdrawal Date: 15-Nov-2000
• ICS: 37.040.20 - Photographic paper, films and plates. Cartridges
• Technical Committee: ISO/TC 42 - Photography
• Drafting Committee: ISO/TC 42/WG 5 - Physical properties and image permanence of photographic materials
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 19-Aug-2010
• Completion Date: 13-Dec-2025
• Directive: 2017-01-2140 - Uredba o varstvu dokumentarnega in arhivskega gradiva

Relations

• Revised: ISO 18911:2010 - Imaging materials - Processed safety photographic films - Storage practices
• Effective Date: 04-Feb-2009
• Revises: ISO 5466:1996 - Photography - Processed safety photographic films - Storage practices
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 18911
First edition
2000-11-01
Imaging materials — Processed safety
photographic films — Storage practices
Matériaux pour image — Films photographiques de sécurité traités —
Techniques d'archivage
Reference number
©
ISO 2000
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ii © ISO 2000 – All rights reserved

Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Film enclosures.3
5 Storage housings.5
6 Storage rooms.5
7 Environmental conditions.6
8 Fire-protective storage (see annex K) .10
9 Film identification, handling, and inspection (see annexes B, H and I) .10
Annex A (informative) Numbering system for related International Standards.12
Annex B (informative) Distinction between storage (record) copies and work (reference) copies.13
Annex C (informative) Advantages and disadvantages of protective (sealed) enclosures.14
Annex D (informative) Air-entrained and gaseous impurities .15
Annex E (informative) Humidity during storage.16
Annex F (informative) Temperature during storage .17
Annex G (informative) Temperature/relative humidity relationship.18
Annex H (informative) Historic photographic records .20
Annex I (informative) Microenvironments .21
Annex J (informative) Silver image degradation.22
Annex K (informative) Fire protection.23
Bibliography.24
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 18911 was prepared by Technical Committee ISO/TC 42, Photography.
This first edition cancels and replaces the fourth edition of ISO 5466:1996, of which it constitutes a technical
revision.
This International Standard is one of a series of International Standards dealing with the physical properties and
stability of imaging materials. To facilitate identification of these International Standards, they are assigned a
number within the block from 18900 to 18999 (see annex A).
Annexes A to K of this International Standard are for information only.
iv © ISO 2000 – All rights reserved

Introduction
The value of records used in archives, museums, libraries, government, commerce and universities has focused
attention on the care of these records to ensure their longest possible life (see [1, 2, 3] in the bibliography).
Photographic film is an important documentary and pictorial material, and there is a recognized need for
information on safeguarding photographic film having legal, scientific, industrial, artistic or historical value.
Films are susceptible to degradation from many sources. These factors may be divided into three general
categories as follows.
a) Nature of the photographic film
The stability of photographic film records depends on the physical and chemical nature of the film. The specification
for safety photographic film which is suitable for storage is described in ISO 18906.
For preservation purposes, processed photographic films are classified according to their life expectancy or LE
designation. These are specified in the appropriate International Standards. The term “archival” is no longer
specified to express longevity or stability in International Standards on imaging materials, since it has been
interpreted to have many meanings that range from “preserving information forever,” which is unattainable, to
“temporary storage of actively used information.”
For optimum preservation of photographic information, a high LE film should be used, and it should be stored under
extended-term storage conditions. A film material suitable for preservation is silver-gelatin type film on polyester
base that meets the requirements of ISO 10602. However, this International Standard also applies to processed
colour, diazo (ISO 8225), vesicular (ISO 9718) and thermally processed silver (ISO 18919) films. Although these
film types may not have as high an LE designation, excellent keeping properties have been obtained with many of
them.
b) Photographic processing of the film
For black-and-white silver-gelatin type film, ISO 10602 specifies a maximum residual thiosulfate level for different
LE classifications and a residual silver compounds level.
For diazo film, ISO 8225 specifies a proper development test. ISO 9718, for vesicular film, includes both a proper
development test and a residual diazonium salt test.
c) Storage conditions
The conditions under which safety photographic film records should be stored are extremely important for the
preservation of film and are the subject of this International Standard (see ISO 18906). The same environmental
conditions are recommended for nitrate-base films, but they shall be stored in a separate storage area having
suitable fire protection safeguards (see [4] in the bibliography).
The important elements affecting preservation of processed film are humidity, temperature and air pollutants, as
well as the hazards of fire, water, light, fungal growth, insects, microbiological attack, contact with certain chemicals
in solid, liquid or gaseous form, and physical damage. Direct contact with other generic types of film can be
detrimental to either film.
The extent to which humidity, temperature, and atmospheric contaminants or variations thereof can be permitted to
reach beyond recommended limits without producing adverse effects will depend upon the duration of exposure,
the biological conditions conducive to fungal growth, and the accessibility of this atmosphere to the emulsion and
support surfaces. Exposure to high temperatures, and in particular to high humidities, can lead to degradation of
the film support and the photographic emulsion (see [5, 6, 7] in the bibliography). Cellulose ester base films are
more subject to base degradation than polyester base films.
There are two levels of storage conditions: medium-term and extended-term. Medium-term storage can be used for
films where the information is to be preserved for a minimum of 10 years, while extended-term storage conditions
can extend the useful life of a majority of freshly processed films to 500 years. However, extended-term storage
conditions will prolong the life of all films, independent of age, type or processing conditions. The storage protection
provided by each level will differ in degree, as will the cost of providing and maintaining the storage facility.
Immediate availability of space and cost may need to be considered when selecting storage conditions. It is
recognized that many facilities may not be able to obtain the low humidity and low temperature levels specified in
this International Standard because of energy considerations, climate conditions or building construction. Such
deviation from the specified conditions will reduce the degree of protection offered, and in such cases maintaining a
humidity and temperature as low as possible will still provide some benefits.
This International Standard is not designed to provide protection against natural or man-made catastrophes, with
the exception of fire and associated hazards which are sufficiently common to warrant inclusion of protection
measures.
In addition to the recommendations in this International Standard, good storage practices must consider the filing
enclosure. These are covered in ISO 18902.
vi © ISO 2000 – All rights reserved

INTERNATIONAL STANDARD ISO 18911:2000(E)
Imaging materials — Processed safety photographic films —
Storage practices
1 Scope
This International Standard provides recommendations concerning the storage conditions, storage facilities,
handling and inspection for all processed safety photographic films (hereafter referred to as photographic film) in
roll, strip, aperture-card or sheet format, regardless of size.
This International Standard is applicable to extended-term and medium-term storage of photographic film as
defined in clause 3.
It is applicable to photographic film records intended as storage copies, which should not be in frequent use. It
does not apply to “work” or “use” copies (see annex B).
This International Standard, while intended for materials that are properly processed, should also be of
considerable value in prolonging the useful life of photographic film whose processing conditions are unknown, or
that have been toned, retouched, or have markings with materials of uncertain or unknown stability.
This International Standard is applicable only to safety photographic film (see ISO 18906). Nitrate-base films are
hazardous (see [8] in the bibliography) and are not covered by this International Standard. They require special
storage considerations (see [4] in the bibliography), but the environmental conditions specified in this International
Standard are applicable.
The storage of photographic prints and photographic plates requires different considerations. They are not covered
in this International Standard, but are described respectively in ISO 18920 and ISO 18918.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
1)
ISO 18906:— , Imaging materials — Photographic films — Specifications for safety film.
ISO 8225:1995, Photography — Ammonia-processed diazo photographic film — Specifications for stability.
ISO 9718:1995, Photography — Processed vesicular photographic film — Specifications for stability.
ISO 10602:1995, Photography — Processed silver-gelatin type black-and-white film — Specifications for stability.
1)
ISO 18915:— , Imaging materials — Methods for the evaluation of the effectiveness of chemical conversion of
silver images against oxidation.
1) To be published.
ISO 14523:1999, Photography — Processed photographic materials — Photographic activity test for enclosure
materials.
ISO 18902:2000, Imaging materials — Processed photographic films, plates and papers — Filing enclosures and
storage containers.
ISO 18919:1999, Imaging materials — Thermally processed silver microfilm — Specifications for stability.
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
archival medium
recording material that can be expected to retain information forever, so that such information can be retrieved
without significant loss when properly stored
NOTE There is, however, no such material and it is not a term to be used in International Standards or system
specifications.
3.2
duplicate
reproduction of a master, retaining the same polarity and size
3.3
extended-term storage conditions
storage conditions suitable for the preservation of recorded information on the majority of freshly and properly
processed photographic films for 500 years
3.4
fire-protective storage
facility designed to protect records against excessive temperatures, water and other fire-fighting agents, and steam
developed by insulation of safes or caused by the extinguishing of fires and collapsing structures
3.5
life expectancy
LE
length of time that information is predicted to be acceptable in a system at 21 °Cand50%RH
3.6
LE designation
rating for the life expectancy (3.5) of recording materials and associated retrieval systems
NOTE The number following the LE symbol is a prediction of the minimum life expectancy in years for which information
can be retrieved without significant loss when stored at 21 °C and 50 % RH, e.g., LE-100 indicates that information can be
retrieved after at least 100 years storage.
3.7
macroenvironment
atmospheric conditions (temperature, relative humidity and pollutants) in a large area in which records are kept
3.8
medium-term storage conditions
storage conditions suitable for the preservation of recorded information for a minimum of 10 years
3.9
microenvironment
atmospheric conditions (temperature, relative humidity and pollutants) inside a storage enclosure in which records
are kept
2 © ISO 2000 – All rights reserved

3.10
open enclosure
enclosure that is intended for physical protection against mechanical damage, but is neither light-tight nor airtight
NOTE Such enclosures may be reels, cores, spools, cassettes, magazines, folders, envelopes, cartons, boxes, sleeves,
transparency mounts or aperture cards.
3.11
protective enclosures
impermeable sealed containers, that may also have to be opaque, used for protection from outside factors such as
reactive gases and moisture, including changes in relative humidity, and from light for certain kinds of products
NOTE Such enclosures may be taped cans and sealed envelopes.
3.12
safety photographic film
film that meets the flammability specifications defined in ISO 18906
3.13
storage housing
physical structure supporting materials and their enclosures
NOTE It may consist of drawers, racks, shelves or cabinets.
4 Film enclosures
4.1 Requirements
All enclosures used for medium-term and extended-term storage shall meet the requirements of ISO 18902.
4.2 Film in roll format
4.2.1 Medium-term storage enclosures
Aerial film, microfilm, motion-picture film, and some portrait films are wound on reels or cores and stored in roll
form. The rolls shall all be wound tightly, but not under extreme tensions. A tension caused by 0,3 N of pull-out
force for a 35 mm film width is recommended. Rolls greater than 150 m in length shall be stored so that the radius
of the roll is in the horizontal position and the film is supported on its edges. Rolls less than 150 m in length may
also be stored with the radius of the roll in the vertical position, if the core itself is supported by a horizontal spindle
inserted into the cores so as to avoid pressure on the bottom of the roll. However, if such rolls are on reels or
spools which have flanges, a spindle is not required since the flanges support the weight of the roll.
Motion-picture prints shall be wound with the emulsion surface on the inside of the roll, as this improves
subsequent projection performance (see [9] in the bibliography).
Rolls of photographic film shall be stored in closed containers to provide protection against dirt and physical
damage, unless the film is protected by the storage housing (see clause 5).
Colour, diazo and thermally-processed silver films shall be stored in closed, opaque enclosures or be otherwise
protected from light exposure. Suitable enclosures are containers with telescoping, slip-type, or threaded twist-on
lids. The materials used shall meet the same requirements as those for cores and reels. Closed enclosures are not
necessarily airtight and may provide limited access to ambient air. Therefore, if they are used, the humidity of the
ambient air shall not exceed the recommended limits.
Protective enclosures made from impermeable materials shall be used, where needed, to maintain the humidity
limits of the film (see clause 7), to protect against gaseous impurities in the atmosphere, or when low-temperature
storage is used without humidity control (see annex C). Suitable enclosures are closed containers with friction-type
or threaded, twist-on lids having an incorporated seal. Rubber gaskets shall not be used. Cans within heat-sealed
foil bags also provide protection from high humidity.
Metal containers provide the best protection against gases from the environment. However, they may corrode from
2)
acidic fumes from within the container unless they are protected with an overcoat. Alternative materials are
polystyrene, polyethylene and polypropylene.
4.2.2 Extended-term storage enclosures
For extended-term storage, the requirements of 4.2.1 shall be met. The materials used for reels, cores, and
containers shall meet the requirements of ISO 18902 and ISO 14523. Rubber bands shall not be used for confining
film on reels or cores. If paper bands are used, the paper shall meet, as a minimum requirement, the specifications
described in ISO 18902 and ISO 14523. Films on reels may be confined by tucking the film end between the roll
and the flange. Pressure-sensitive tape, if needed for the enclosure, shall be free from peroxide and pass the
photographic activity test specified in ISO 14523. Pressure-sensitive tape shall not be used in contact with the film.
Films may have possible interactions with other films that are of a different generic type (for example, diazo and
silver-gelatin), as well as with magnetic tapes and optical disks. Films of a different generic type shall not be wound
in the same rolls or stored in the same enclosures. Closed containers are required, unless the photographic film is
protected from dirt and damage by the storage housing (see clause 5).
4.3 Film in sheet and slide format
4.3.1 Medium-term storage enclosures
Film in sheet form may be stored in envelopes of paper or plastic foil, folding cartons, boxes, file folders, aperture
cards, or film strip jackets. Photographic slides may be stored in cardboard, metal or plastic boxes. Colour, diazo,
and thermally-processed silver films shall be stored in opaque envelopes or folders, or otherwise protected from
light exposure. Films should not be stacked, as this could cause excessive pressure on the lowermost sheets.
When in direct contact with the surface of the photographic film, the paper or plastic material used for envelopes,
sleeves, jackets, folders, boxes and cartons shall meet, as a minimum requirement, the specifications described in
ISO 18902 and ISO 14523.
Suitable plastic enclosure materials are uncoated polyester (polyethylene terephthalate), polystyrene, polyethylene
and polypropylene. Glassine envelopes and chlorinated, nitrated or highly plasticized sheeting shall be avoided.
Specifically, cellulose nitrate and polyvinyl chloride are not acceptable.
Protective enclosures shall be used, where needed, to maintain humidity within the limits recommended for the
specific film type (see clause 7), to protect against gaseous impurities in the atmosphere, or when low-temperature
storage is used without humidity control. Heat-sealable envelopes, consisting of aluminum foil extrusion coated with
clear polyethylene on the inside and laminated to a suitable paper sheet on the outside, have been successfully
used as sealed enclosures. Precautions should be taken in handling these envelopes, so that they are not
punctured. To provide greater protection against pinholes, a double bagging technique is recommended.
The adhesive used for seams and joints shall also meet the requirements of ISO 18902 and ISO 14523. The filing
enclosure shall be constructed so that any seam or joint will be at the edge of the enclosure and not in contact with
the image layer.
2)
Any film that is actively releasing acidic fumes shall be stored in plastic or acid-neutralizing envelopes.
2) Some vesicular films give off acidic fumes that may interact with silver, diazo or dye-gelatin type films. Decomposing
acetate-base films release acetic acid, which further catalyses base degradation.
4 © ISO 2000 – All rights reserved

4.3.2 Extended-term storage enclosures
For extended-term storage, the requirements of 4.3.1 shall be met except that film shall not be stored in cardboard
enclosures.
Photographic-quality gelatin, modified and photographically inert starch, some acrylic and polyvinyl acetate
adhesives and methyl cellulose are suitable for use with paper storage enclosures. Pressure-sensitive
(permanently tacky) adhesives shall meet the specifications of ISO 18902 and ISO 14523.
Films may have possible interactions with other films that are of a different generic type (for example, diazo and
silver-gelatin), as well as with magnetic tapes and optical disks. Films of different generic types shall not be
interfiled or be in physical contact.
5 Storage housings
Photographic film should be stored in closable housings, such as drawers or cabinets, or on shelves and racks
enclosed by tightly fitting doors in order to provide protection from dust and dirt. Alternatively, open shelves and
racks may be used if the film is in closed containers. The storage housing materials shall be non-corrosive as
described in ISO 18902. They shall also be non-combustible and chemically inert. Wood, pressed-board, particle-
board, plywood and other such materials shall be avoided due to their combustible nature and the possibility of
producing active deteriorating agents as they age.
The finish on storage housing materials shall be durable and should not contain substances that can have a
deleterious effect on stored photographic film. Adverse effects may be produced by finishes containing chlorinated
or highly plasticized resins, or by solvents off-gassing from freshly applied finishes. Paints used on cabinets may
give off peroxides, solvents and other contaminants for up to three months after being applied. Metal housing
materials that have been powder coated (a solvent-free finish process in which electrostatically applied resin
particles are fused by heat) or cabinets made from stainless steel or anodized aluminum are recommended.
When air-conditioned individually, storage housings shall be arranged to permit interior circulation of air to all
shelves and drawers holding film containers so as to provide uniform humidity conditions. Storage housings,
located in rooms conditioned in accordance with 7.1, shall be provided with ventilation openings that permit access
of air to the interior. Such openings shall not interfere with the requirements for fire-protective storage or water
protection.
Films and other materials that release acidic fumes, magnetic tapes and optical disks shall not be stored in the
same storage housing as other photographic products.
6 Storage rooms
6.1 Medium-term storage rooms
Rooms and areas used for film storage should be located in the same area as rooms containing provisions for
inspection and viewing of the film. Good housekeeping is essential. Walls and enclosed air-conditioned spaces
shall be designed to prevent condensation of moisture on interior surfaces and within walls, especially during
periods of low exterior temperatures when the walls can be cooled below the dew-point of the air.
Provisions shall be made against damage of film by water from floods, leaks, sprinklers, and from the steam
released from masonry walls during a fire. Storage rooms or vaults should be located above basement levels
where possible. A special storage room separated from the work areas, for film records of medium-term interest,
generally will not be required, provided that the conditions recommended in 7.1.2 are maintained.
Films that are not essentially free from release of acidic fumes, such as some vesicular films, shall be stored in
separate storage rooms. Films showing any sign of chemical degradation, such as the presence of acidic fumes,
shall be stored in a separate storage room having a separate circulating-air system.
6.2 Extended-term storage rooms
For extended-term storage, the requirements of 6.1 shall be met.
The value of photographic film kept for long-term purposes makes it advisable to provide a storage room or vault
separate from medium-term storage facilities, temporary storage facilities, offices or work areas. Storage rooms for
films that are not essentially free from acid release shall have a separate circulating-air system (see annex D).
Storage rooms have been constructed in caves and mines and have proven very satisfactory when requirements
are met for environmental conditions (see 7.1) and air purity (see 7.3).
7 Environmental conditions
7.1 Temperature and humidity specifications for storage (see annexes E, F and G)
7.1.1 Recommended temperature and relative humidity
The recommended temperature and relative humidity conditions given in Table 1 shall be maintained either within
individual storage housings or within storage rooms containing such housings.
Table 1 — Maximum temperatures and relative humidity ranges for extended-term storage
a, b a, c
Maximum temperature Relative humidity range
Image Base
°C %
d
2 20-50
Black-and-white silver-gelatin
(see ISO 10602)
e
5 20-40
Cellulose esters
7 20-30
d
Black-and-white silver-gelatin
(see ISO 10602)
Thermally or processed silver
Polyester 21 20-50
(see ISO 18919)
Vesicular (see ISO 9718)
Silver dye bleach
e
Colour (chromogenic) 20-50
� 10
Cellulose esters
20-40
� 3
Diazo (see ISO 8225) Polyester 2 20-30
a
See annex H for storage of historic still photographic records.
b
Cycling of temperature shall not be greater than � 2 °C over a 24 h period.
c
Cycling of relative humidity shall not be greater than � 5 % RH over a 24 h period.
d
If there is concern about the possibility of silver image oxidation due to atmospheric contaminants, poor quality enclosures, and/or
excessively high temperature and humidity levels, a post-process chemical conversion treatment can be used to provide added protection
(see ISO 18915).
e
This includes cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate.
7.1.2 Medium-term storage environment
The average relative humidity (RH) of a medium-term storage environment shall not exceed 50 % RH, and the
maximum relative humidity shall not exceed 60 % RH. Ideally, the maximum temperature for extended periods
should not exceed 25 °C, and a temperature below 21 °C is preferable. The peak temperature for short time
periods shall not exceed 32 °C.
6 © ISO 2000 – All rights reserved

Short-term cycling of temperature shall be avoided. Cycling of relative humidity shall not be greater that� 10 % RH
over a 24 h period. Cycling of temperature shall not be greater than� 5 °C over a 24 h period.
Protection may be increased by storing film at low temperature and low relative humidity.
7.1.3 Extended-term storage environment (see annex G)
7.1.3.1 Recommended environment for black-and-white films
The rate of most chemical reactions, such as the degradation of film base and the discolouration of the image silver
by oxidation, is lowered with decreasing temperature and decreasing relative humidity. Consequently, life
expectancy is increased as either storage temperature or storage humidity is lowered. Moreover, a lower storage
temperature can compensate for a higher humidity to provide the same life expectancy (see annex G). For this
reason, several relative humidity/temperature combinations can be used for an extended-term storage environment
as specified in Table 1.
Higher relative humidity ranges can be employed if the average temperature is reduced, but the maximum relative
humidity shall not exceed 50 %. Cycling of relative humidity shall be no greater than� 5 % RH over a 24 h period.
Cycling of temperature shall be no greater than� 2 °C over a 24 h period.
An alternative procedure to controlling the macroenvironment is to condition the film to the recommended relative
humidity at room temperature, place it in hermetically sealed or taped containers, and then put it in cool storage
(see [10] in the bibliography). Roll and sheet films generally are protected adequately against moisture when
placed within two heat-sealed foil bags from which as much air as possible has been expelled before sealing. Roll
films are provided with greater physical protection if first placed in cans. The double-bag arrangement reduces the
possibility of air leakage through pin holes, but does not guarantee it. However, except in rare instances, it does
provide the desired moisture conditions inside the inner bag and, therefore, permits the use of cold storage vaults
or reasonably-priced deep-freeze units. It is essential to limit, as much as possible, the volume of free air in the
sealed film container.
It is difficult to specify in this International Standard what the exact relative humidity and temperature of storage
should be, since they depend upon the value of the film, the past storage history, the length of time the film is to be
kept, the size of the vault, the cost of various options, and the climate conditions where the facility is to be located.
The cost/protection ratio has to be determined by the individual facility. Another very important factor is the exact
mix of the photographic objects in the collection, i.e., whether photographic prints and plates are included and
whether the materials are new or old.
Low relative humidities can cause excessive strain on the emulsion and result in high curl. Low humidities can also
cause serious problems with older historic records (see annex H). The environmental conditions chosen should fall
within the guidelines of Table 1.
The recommended humidity and temperature conditions can be maintained either within individual storage
housings or within storage rooms containing such housings. When the regulation of the macroenvironment is not
possible, the microenvironment shall be controlled by means such as molecular sieves or silica gel, or by
conditioning to a lower humidity (see annex I).
Very low humidity conditions may produce brittleness or curl in films having a gelatin emulsion, by extraction of
moisture from the emulsion. In such cases, it is good practice to recondition the film to a higher humidity prior to
use.
7.1.3.2 Recommended environment for colour films
The storage temperature for colour films shall be 2 °C or below for chromogenic materials (see [11, 12] in the
bibliography) and 21 °C or below for silver dye bleach materials. This can be provided by a storage room controlled
at the desired temperature and at the recommended relative humidity. Several relative humidity/temperature
combinations can be used as specified in Table 1.
As an alternative method, use the procedure described in the third paragraph of 7.1.3.1.
The user should balance the capital and operating cost of cold storage vaults or deep-freeze units with the labour
and material cost of bagging film.
7.1.3.3 Moisture-conditioning time
Moisture equilibration requires considerably more time than temperature equilibration. The time needed for films to
reach moisture equilibrium with a given atmosphere depends on the following main factors:
� the film format (sheets, rolls);
� the packing density and volume of sheet-film stacks or the number of convolutions of film rolls;
� the moisture permeability of enclosure materials and/or containers;
� the difference between the initial and the desired final moisture content of the films;
� the temperature at which the moisture conditioning occurs.
A combination of these factors can prolong conditioning periods and may compromise the effectiveness of low
temperature storage vaults, if the conditioning is expected to take place in storage. For example, a 150-sheet stack
will condition in less than two weeks at room temperature but will require six months at sub-zero temperature
(see [13] in the bibliography).
For these reasons, preconditioning of films may be necessary before they are placed in their controlled storage
place. This can be accomplished with sheet films by exposing them to freely circulating air (see 7.3 for air purity) of
suitable temperature and relative humidity for 24 h. Longer periods will be needed if the sheets are in stacks.
Moisture equilibration of roll films takes much longer. Here again, free access of air will shorten the required
conditioning period, and rolls in moisture-permeable enclosures will require less time than those in closed metal
containers. However, even the latter will come to moisture equilibrium within several months at room temperature
(see [12, 13] in the bibliography). Film rolls that contain more than the desired quantity of moisture can be dried by
keeping them for two to three weeks in taped metal containers that contain suitable amounts of silica gel or a
molecular sieve.
If the relative humidity of the use environment is chosen to match that of the storage environment, moisture-
conditioning procedures can be reduced or eliminated. Matching the relative humidity levels between use and
storage has the added advantage of reducing physical stress on the film caused by relative humidity cycling
between storage and use. Unmatched humidity levels will have a strong influence on the time required to reach
moisture equilibrium.
7.1.3.4 Warm-up time
Films stored at temperatures significantly below room temperature will require some warm-up time before they can
be used, in order to prevent absorption or condensation of moisture on cold film surfaces. This warm-up procedure
requires that an adequate vapour barrier be wrapped around the film contents during the warm-up period.
Adequate time must be provided to allow the total volume of film to approach room temperature (see annex F). The
required warm-up time can vary between 1 h and 1 d, depending on the package size, degree of insulation and
temperature differential.
7.2 Air-conditioning requirements
Properly controlled air-conditioning may be necessary for maintaining humidity and temperature within the limits
specified, particularly for extended-term storage where the requirements are more stringent than for medium-term
storage. Slightly positive air pressure shall be maintained within the storage room or vault. Air-conditioning
installations and automatic fire-control dampers in ducts carrying air to or from the storage vault shall be
constructed and maintained on the basis of the recommendations contained in appropriate national standards and
8 © ISO 2000 – All rights reserved

3)
regulations . They shall also conform with recommendations for fire-resistive file rooms contained in appropriate
4)
national standards and regulations . Masonry or concrete walls may release steam from internally bonded water
when heated in a fire. A vapour barrier is required for such vaults, or sealed containers shall be used.
Automatic control systems are recommended, and they shall be checked frequently with a reliable hygrometer that
has been properly calibrated to determine that the humidity limits specified in Table 1 are not being exceeded.
Where air-conditioning is not practical, high humidities may be lowered by electrical refrigeration-type dehumidifiers
controlled with a hygrostat. Inert desiccants, such as chemically pure silica gel, may be used, provided the
dehumidifier is equipped with filters capable of removing dust particles down to 0,3�m in size and is controlled to
maintain the relative humidity specified in 7.1.
Dehumidification may be required in storage areas, such as basements and caves, that have inherently low
temperatures and frequently exceed the upper humidity limit.
Humidification is necessary if the prevailing relative humidity is less than that recommended in 7.1, or if physical
troubles such as curl or brittleness are encountered with active files. If humidification is required, a controlled
humidifier shall be used. Water trays or saturated chemical solutions shall not be used because of the serious
danger of over-humidification.
7.3 Air purity (see annex D)
Solid particles, that may abrade film or react with the image, shall be removed by mechanical filters from air
supplied to housings or rooms used for storage. These mechanical filters are preferably a dry-media type having an
arrestance rating of not less than 85 %, as determined by tests contained in appropriate national standards and
5)
regulations . Filters shall be of a non-combustible type, meeting the construction requirements of appropriate
6)
national standards and regulations .
For maximum storage life, photographic film shall be in a clean condition before being placed in storage.
Gaseous impurities such as sulfur dioxide, hydrogen sulfide, peroxides, ozone, acid fumes, ammonia and nitrogen
oxides can cause deterioration of the film base or image degradation in some films (see annex J). They can be
removed from the air by suitable washers or absorbers. An extended-term storage film vault should be located as
far as possible from an urban or industrial area, where contaminants can be present in harmful concentrations.
Storage of film in sealed containers in accordance with clause 4 will afford adequate protection against outside
pollutants.
Since paint fumes may be a source of oxidizing contaminants, film shall be removed from either an extended-term
or medium-term storage area for a 3 month period when the area is freshly painted.
Gases given off by decomposing nitrate-base film will damage or destroy the image on safety film records stored in
the same area (see [21] in the bibliography). Therefore, safety film shall not be stored with nitrate-base films, either
in the same room or in rooms connected by ventilating ducts.
7.4 Light
Normally, film is kept under dark conditions. This is recommended practice, as light can be detrimental to some
images.
3) For example, see [14, 15] in the bibliography.
4) For example, see [16, 17] in the bibliography.
5) For example, see [18, 19] in the bibliography.
6) For example, see [19, 20] in the bibliography.
8 Fire-protective storage (see annex K)
Enclosure materials for fire-resistant storage shall be sufficiently fire-resistant that, after heating for 4 h at 150 °C,
they will not ignite or release more reactive fumes than the film itself. Many enclosure materials will melt or become
badly distorted at this temperature. This melting or distortion shall not cause damage to the film or prevent it from
being removed from the enclosure. The materials used in reels or cores shall be neither more flammable nor more
decomposable than the film that is stored on them.
For protection against fire and associated hazards, the film shall be placed in closed containers in either
7)
fire-resistant vaults or insulated record containers (Class 150) . If fire-resistant vaults are used, they shall be
4)
constructed in accordance with recommendations contained in appropriate national standards and regulations
with particular care taken for protection from steam.
When the quantity of film is not too great, insulated record containers (Class 150) conforming to appropriate
7)
national standards and regulations are suitable . They shall not exceed an interior temperature of 65 °C and an
interior relative humidity of 85 % when given a fire-exposure test from 1 h to 4 h depending on the classification of
the record container. Insulated record containers shall be situated on a ground-supported floor if the building is not
fire resistant.
For the best fire protection, duplicate copies of film records shall be placed in a g
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