ISO 6051:1997
(Main)Photography — Processed reflection prints — Storage practices
Photography — Processed reflection prints — Storage practices
Photographie — Tirages traités par réflexion — Directives pour l'archivage
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 6051
Fourth edition
1997-12-01
Photography — Processed reflection
prints — Storage practices
Photographie — Tirages traités par réflexion — Directives pour l'archivage
A
Reference number
ISO 6051:1997(E)
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ISO 6051:1997(E)
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 collab-
orates closely with the International Electrotechnical Commission (IEC) on
all matters of electrotechnical standardization.
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.
International Standard ISO 6051 was prepared by Technical Committee
ISO/TC 42, Photography.
This fourth edition cancels and replaces the third edition (ISO 6051:1992),
of which it constitutes a technical revision.
Annexes A to J of this International Standard are for information only.
© ISO 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
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Printed in Switzerland
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ISO ISO 6051:1997(E)
Introduction
Photographic and other reflection prints, including hard copy output from
digital imaging systems, have become increasingly important as documen-
tary and pictorial reference material in libraries, government, commerce
and academia. This has focused attention on the importance of the preser-
vation of such materials to ensure their longest possible life.
The stability and useful life of reflection prints depend on their physical and
chemical properties, as well as on the conditions under which they are
stored and used. This International Standard provides recommendations
on proper storage conditions.
The important elements affecting the useful life of reflection prints are as
follows:
— humidity and temperature of the storage environment;
— hazards of fire, water, and light exposure;
— fungal growth;
— contact with certain chemicals in solid, liquid, or gaseous form;
— physical damage.
The extent to which the relative humidity and temperature of the storage
environment, or variations of both, can be permitted to reach beyond
recommended limits without producing adverse effects will depend upon
the duration of exposure, on biological conditions conducive to fungal
growth, and on the accessibility of the atmosphere to the print surfaces.
The term “archival” is no longer used to express longevity or stability in
International Standards on imaging materials because the meaning of
“archival” has become too ambiguous, ranging from preserving documents
“forever”, which is unattainable, to temporary storage of actively used
materials.
This International Standard defines two levels of recommended storage
conditions: medium-term and extended-term. Medium-term conditions can
be used when it is desired to preserve information for at least 10 years.
Extended-term conditions shall be used when it is desired to preserve
information for as long as possible. Extended-term conditions shall be used
when it is desired to preserve information for as long as possible.
Extended-term conditions will prolong the life of all prints, even those not
optimized for permanence.
The space requirements and costs for establishing and operating the two
levels of storage conditions (medium-term and extended-term) differ
significantly. Furthermore, the specified limits of temperature and relative
humidity for both sets of storage conditions may not be realizable due to
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ISO 6051:1997(E) ISO
budgetary constraints, energy considerations, climatic condition, building
construction, etc. However, it must be recognized that any deviation from
the specified conditions will reduce the effectiveness of the storage
environment. If such deviation is unavoidable, the lowest possible storage
temperature should be provided. In any event, the best preservation of
prints will be attained with extended-term storage conditions.
The recommendations of this International Standard for the storage of
reflection prints encompass enclosures, housing, rooms, atmospheric
conditions, fire protection, and inspection procedures. With the exception of
fire and associated hazards that are sufficiently common to warrant
inclusion of protective measures, this International Standard does not
pertain to means or methods for protecting reflection prints against natural
or man-made catastrophes.
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INTERNATIONAL STANDARD ISO ISO 6051:1997(E)
Photography — Processed reflection prints — Storage
practices
1 Scope
1.1 This International Standard specifies dark storage conditions, storage facilities, and procedures for handling
and inspection of reflection prints of all types and sizes.
1.2 This International Standard covers reflection prints on the following opaque supports:
— fibre base paper;
— RC (resin coated) base paper;
— opaque plastic films (polyester, cellulose acetate, etc.).
This International Standard covers the following black-and-white silver gelatin prints:
— wet-processed, including those that have been chemically treated to improve the permanence of the silver
image and/or to modify its colour (e.g. with gold, selenium or sulfur formulations);
— diffusion transfer (e.g. Polaroid instant prints);
— stabilization-processed (which contain the silver image as well as invisible, chemically stabilized silver halides);
— heat-processed.
This International Standard covers the following multi-colour and monochrome photographic prints:
— chromogenic, washed and stabilized;
— silver dye bleach;
— dye transfer;
— diffusion transfer (e.g. Polaroid instant prints, peel-apart or integral);
— pigmented gelatin (carbon, carbro, etc.).
This International Standard covers black-and-white and colour reflection prints made with the following systems:
— thermal dye transfer (commonly referred to as dye sublimation);
— thermal wax transfer;
— electrophotographic;
— ink jet;
— diazo.
1.3 Recommendations for storage of photographic films are given in ISO 5466 and for storage of processed
photographic plates in ISO 3897. Print material on translucent film supports intended to be viewed primarily by
transmitted light should be stored in accordance with ISO 5466.
1.4 This International Standard applies to medium-term and extended-term storage conditions as defined in
clause 3.
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2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 5466:1995, Photography — Processed safety photographic films — Storage practices.
ISO 3897:1997, Photography — Processed photographic plates — Storage practices.
ISO 10214:1991, Photography — Processed photographic materials — Filing enclosures for storage.
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1 A recording material that can be expected to retain information forever so that such
archival medium:
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 material or system
specifications.
3.2 extended-term storage conditions: Storage conditions suitable for the preservation of recorded information
having a permanent value.
3.3 fire-protective storage facilities: Facilities designed to protect records against excessive temperatures,
water, other fire-fighting agents, steam developed by insulation of safes or caused by the extinguishing of fires, and
collapsing structures.
3.4 fire-resistive vaults: Fire-resistive vaults as defined in appropriate national standards and regulations ([1, 2]
in annex J).
3.5 insulated record containers (Class 150): Insulated record containers [Class 150] as defined in appropriate
national standards and regulations ([3, 4] in annex J).
3.6 life expectancy (LE): The length of time that information is predicted to be retrievable in a system under
extended-term storage conditions.
3.7 medium-term storage conditions: Storage conditions suitable for the preservation of recorded information
for a minimum of 10 years.
3.8 storage container: A box or can used for storage of prints.
3.9 storage enclosure: Any item in close or direct contact with recording material such as folders, envelopes,
sleeves, albums and mats.
3.10 storage housing: A physical structure supporting materials and their enclosures. It may consist of drawers,
racks, shelves or cabinets.
4 Enclosures and containers
All enclosures and containers used for medium-term and extended-term storage shall meet the requirements of
ISO 10214. This includes enclosures and containers that are in either direct or indirect contact with the prints.
Reflection prints may be stored in envelopes or sleeves of paper or plastic, file folders, folding cartons, boxes or
albums, or may be matted. Colour prints shall be protected from light exposure.
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ISO ISO 6051:1997(E)
Generally, prints smaller than 28 cm × 36 cm in size may be stored vertically, but must be placed between rigid
supports to minimize slumping and curling. Prints 28 cm × 36 cm or larger should be stored horizontally, unless
mounted on rigid supports. Stacks of horizontal prints should be less than 5 cm high to prevent excessive pressure
on prints at the bottom.
Multiple prints, stored within an enclosure or container, shall be oriented emulsion sides against back sides, never
emulsion against emulsion.
Suitable plastic enclosure materials are uncoated polyester (polyethylene terephthalate), high-density polyethylene,
and polypropylene. Other plastics may be satisfactory, but there has been no extended experience with such
materials. Glassine envelopes and chlorinate, nitrated or highly plasticized sheeting shall be avoided.
Sealed enclosures shall be used, where needed due to adverse environmental or pollution conditions, to maintain
the humidity levels of the prints, to protect against gaseous impurities in the atmosphere, or when low-temperature
storage is used without humidity control. Heat-sealed foil bags can provide this protection.
The adhesive used for seams and joints shall also meet the requirements of ISO 10214. The filing enclosure shall
be so constructed that the seam or joint will be at the edge of the enclosure and not in contact with the image layer.
Photographic-quality gelatin, modified starch, and acrylic adhesives are suitable adhesives for use with paper.
For maximum life, prints shall be in a clean condition before being placed in storage and shall be inspected
periodically thereafter, as outlined in 9.3.
5 Storage housings
Reflection prints should be stored in closed storage housings such as drawers or cabinets, in storage cabinets with
doors, or on open shelves when enclosed inside containers. The storage housing materials shall be non-
combustible and non-corrosive, for example, anodized aluminum, stainless steel, or steel with a non-plasticized
synthetic resin-powder coating. Because of their combustible nature and the possibility of their producing active
fading agents as they age, wood, pressboard, particle-board, plywood and other such materials shall be avoided.
The finish on the housing materials shall be durable and shall not have a deleterious effect on the stored prints.
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 application. Cabinets made of stainless steel or anodized aluminum are
recommended. Metal housing materials that have been powder-coated (a layer of resin particles that are
electrostatically applied to the surface of the metal and then fused to the surface using heat without the use of
chemical solvents) are also recommended.
When air-conditioned individually, storage housings shall be arranged to permit interior circulation of air to all
shelves and drawers holding print containers so as to provide uniform humidity conditions. Storage housing 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 requirements for fire protection or water protection.
Different types of prints and films shall not be stored in the same enclosure or storage container. Magnetic tapes or
optical disks shall not be stored in the same storage vault as photographic prints.
6 Storage rooms
6.1 Medium-term storage rooms
Rooms and areas used for print storage should be located in the same area as rooms containing provisions for
inspection and viewing of prints. 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 may be cooled below the dew-point of the air.
Provisions shall be made against damage of prints by water from floods, leaks, sprinklers, and the like. A special
storage room separated from the work areas for print records of medium-term interest generally will not be required,
provided the conditions recommended in 7.1 are maintained.
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ISO 6051:1997(E) ISO
6.2 Extended-term storage rooms
For extended-term storage, the requirements of 6.1 shall be met. The value of photographic prints 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.
7 Environmental conditions
7.1 Storage specifications (see annexes B, C and D)
The storage temperature and relative humidity are given in table 1.
Table 1 — Storage temperature and relative humidity
1)
Process Medium-term storage Extended-term storage
Relative Maximum Relative
Maximum
humidity range temperature humidity range
temperature
2) 3) 4) 5)
°C % °C %
Black-and-white silver 25 20 to 50 18 30 to 50
Silver dye bleach
Dye/silver diffusion
transfer (instant)
Pigment
Diazo
6)
Chromogenic dye 25 20 to 50 2 30 to 40
7)
All others 25 20 to 50 30 to 50
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1) Formerly known as “archival storage”, see introduction. For storage of historic still-photographic prints, see annex E.
2) Cycling of the temperature shall not be greater than – 5 °C over a 24 hour period; the peak temperature shall not exceed
30 °C.
3) Cycling of the relative humidity shall not be greater than – 10 % over a 24 hour period.
4) Cycling of the temperature shall not be greater than – 2 °C over a 24 hour period; the peak temperature shall not exceed
the specified maximum temperatures. No lower temperature limit is specified; however 2 20 °C is a practical lower limit
when considering the mitigating effect on life expectancy by time out of storage, see annex D.
5) Cycling of relative humidity shall not be greater than – 5 % over a 24 hour period.
6) Generally, the stability of chromogenic prints is 10 to 15 times greater when stored at 2 °C compared to room
temperature storage. The extended-term storage conditions specified for chromogenic prints differ from those specified for
chromogenic colour film materials. The two temperature limits specified for prints are also specified for film; the
corresponding relative humidity ranges specified for prints are higher due to potential physical problems such as curl and
brittleness. The following environmental conditions meet the recommendations of both standards and are suitable for
storage of both types of materials: a maximum temperature of 2 °C and an RH of 30 % and a maximum temperature of 3 °C
and an RH range of 30 % to 40 %. Older and historic chromogenic color print materials are comparatively less stable and
may be stored at a colder temperature to increase the life expectancy of the prints (see annex E).
7) The rates of degradation and the potential for physical problems due to low temperature and/or low relative humidity
storage with print materials using newer technologies, such as thermal wax transfer, thermal dye transfer (commonly known
as dye sublimation), electrophotographic colour, and ink jet, are currently unknown.
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ISO ISO 6051:1997(E)
7.1.1 Medium-term storage environment
The maximum temperature for medium-term storage shall be 25 °C, cycling of the temperature shall not be greater
than – 5 °C over a 24 hour period, and the peak temperature shall not exceed 30 °C. Temperature fluctuation is
allowable as long as the relative humidity stays within the specified limits.
The relative humidity for medium-term storage shall be between 20 % and 50 %, and cycling of the relative humidity
shall not be greater than – 10 % over a 24 hour period. The moisture content in prints shall not be greater than the
moisture equilibrium with these relative humidities. Storing prints at the lower limit of the specified relative humidity
range may cause curling of the prints or physical damage may occur during handling (see annex E); prints may
need to be equilibrated to a higher relative humidity prior to use.
7.1.2 Extended-term storage environment
The maximum temperature for extended-term storage shall be as specified in table 1, the variation of the
temperature shall not be greater than – 2 °C over a 24 hour period, and temperature fluctuation is allowable as long
as the relative humidity stays within the specified limits.
The relative humidity for extended-term storage shall be as specified in table 1. The variation of relative humidity
shall not be greater than – 5 % over a 24 hour period. The moisture content in prints shall not be greater than the
moisture equilibrium with these relative humidities.
For black-and-white silver, silver dye bleach, dye/silver diffusion transfer (instant), dye imbibition (transfer), pigment
and diazo, a maximum storage temperature of 18 °C shall be used. Added protection may be obtained for all prints
by low-temperature storage. Low-temperature storage improves the stability of both the print support and the image.
For multi-colour and monochrome chromogenic dye prints and all other types of prints not specified, a maximum
storage temperature of 2 °C shall be used. Excellent keeping behaviour has been obtained by storing colour prints
at such low temperatures. The recommended humidity and temperature conditions may be maintained either within
individual storage housings or within storage rooms containing such housings. Either of the following two methods
may be used in to prolong the useful life of the prints.
a) The first method is to use a storage room controlled at 2 °C and maintained within the recommended relative
humidity range. This method alleviates the need for sealed storage containers, but requires expensive
equipment and facilities to maintain the environmental conditions. One problem is the danger of moisture
precipitation on print surfaces when they are brought into a warm room. This can be avoided by placing prints
in sealed moisture-proof containers or in heavy-gauge self-sealing plastic bags prior to removal from the cold
vault and allowing them to warm above the dew-point prior to opening.
b) The second method is useful when prints are removed only infrequently from storage. In this method, the prints
are equilibrated with air near the low limit of specified relative humidity, then sealed in airtight containers and
placed in cold storage. The required humidity conditioning period for fibre-based prints is 1 day and for RC
(resin coated) prints is 7 days. Special heat-sealable foil bags are commonly used and double-bagging (one
heat sealed bag within another) can be employed to minimize the problem of air leakage through tiny holes in
the bag material. One advantage of this method is that environmental humidity control is not needed and
relatively low-cost freezers or refrigerators can be us
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