ISO/DIS 18928.2:2026(en)

ISO/TC 42

Secretariat: ANSI

Date: 2026-02-03

Imaging materials — Unprocessed photographic films and papers — Storage practices

© ISO 2026

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Contents

Foreword v

Introduction vi

1 Scope 1

2 Normative references 1

3 Terms and definitions 1

4 Storage conditions 1

4.1 General 1

4.2 Relative humidity 1

4.3 Temperature 2

4.4 Gases 2

4.5 Extraneous radiations 2

5 Temperature acclimatization 3

6 Mechanical requirements 3

7 Handling conditions 4

Annex A (informative) Background radiation 5

A.1.1 General 5

Bibliography 6

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.

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This document was prepared by Technical Committee ISO/TC 42, Photography.

This fourth edition cancels and replaces the third edition (ISO 18928:2013) which has been technically revised.

The main changes are as follows:

— typographical errors corrected in Annex A;

— specific reference made to silver halide products to distinguish these from other imaging materials.

— updates to references and storage conditions to reflect contemporary sensitised products. Specifically, the short-term storage condition has been revised down from 21 °C to the recommendations on current Black and White films. A note has been added on the long-term benefits of storage in a refrigerator.

A list of all parts in the ISO 18900 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

International Standards have been written specifying the recommended practices for the storage of the following chemically processed silver halide products:

— safety photographic film (see ISO 18911);

— reflection prints (see ISO 18920);

— photographic plates (see ISO 18918).

This document is concerned with the storage of unprocessed silver halide photographic materials. While many of the recommendations for unprocessed and processed storage are very similar, there are some important differences. These include the very beneficial effects of low temperature and the harmful effects of adverse storage and radiation. ISO guidance is that each document should explicitly consider the relevant stakeholders. The stakeholders identified in this project are:

— photofinishing labs, wholesalers, retailers and others in the silver halide material supply chain

— end users of silver halide materials such as professional and amateur photographers.

The ISO commitment to the consideration of climate science is embodied in the London Declaration. In line with this some guidance is given on the effect of high temperature events on storage conditions.

Imaging materials — Unprocessed photographic films and papers — Storage practices

This document specifies recommended storage conditions for unprocessed silver halide containing photographic materials. It is not applicable to processed films and prints.

This document applies to black-and-white and colour photographic materials (e.g. negative films, positive films, reversal films, positive papers and X-ray films).

There are no normative references in this document.

No terms and definitions are listed in this document.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

The photographic properties of imaging materials change during ageing. These changes result from high temperatures and high relative humidity and may also be influenced by plastics, papers, solvents, lacquers, varnishes, gases (see 4.4), and extraneous radiation (see 4.5). Frequent temperature changes may also have adverse effects.

Changes caused by unfavourable storage conditions may be much greater than those due to variations in original manufacture. It is important to comply with the manufacturer's recommended storage conditions and, where given, to an expiration date.

Films and papers should be exposed and processed as soon as possible after the original package has been opened. Opened packages should be resealed under recommended conditions for further storage.

Films and papers are not usually stored for long periods between exposing and processing. Production schedules, customer needs, latent image fading or growth, etc., are important factors here. If silver halide containing sheet films or papers are not to be processed immediately, they may be stored in commercially available light-tight “paper safes” or in the manufacturer's original container.

Photographic material should generally be kept in equilibrium with 40 % to 60 % relative humidity (RH). Containers shall be kept sealed until the material is used.

The relative humidity of the storage area shall be maintained below 65 % because higher humidity can damage containers (e.g. rust), cause labels, tapes and cartons to deteriorate, and encourage the growth of fungi. It can also induce adhesion (blocking) between adjacent laps or layers.

Humidity below 30 % can make film and paper temporarily brittle and lead to unacceptable curl and possible emulsion cracking.

Recommended temperatures during storage depend on the kind of photographic material and on the duration of storage. General guidelines are given in Table 1. In all cases, the information provided by the manufacturer shall be followed.

When storing for less than a month, photographic materials may be kept at approximately 25 °C. Most manufacturers recommend a maximum temperature of 13 °C for longer periods. Manufacturers' expiration dates can be extended by storing at still lower temperatures. Note that infrared-sensitive films shall be stored at –18 °C.

If films or papers are to be kept for several days or more between exposing and processing, many of the considerations in Clause 4 apply. Storage temperatures should be the same for exposed as for unexposed material.

Table 1 — Storage temperature for films and papers

For very long storage of all types of photographic materials, the recommended storage temperature shall be between –18 °C and –20 °C.

Climate science guides us to consider the effect of high temperature events. For storage periods that may contain high temperature events a domestic refrigerator or freezer (below 4 °C) may provide a suitable and convenient solution for end users.

The manufacturer's recommendations take precedence over the suggested guidelines of Table 1.

Storage rooms shall be protected against harmful gases such as hydrogen sulphide, sulfur dioxide, formaldehyde, oxidizing gases, industrial emissions, and mercury vapour. Any of these may penetrate the container seal and fog or desensitize the material.

Materials shall not be stored in the same area as developer or activator solution.

Photographic materials shall be protected from extraneous penetrating radiation until they are processed. For most materials, a maximum of 1,29 ⨯ 10⁻⁴ C/kg is recommended. However, the maximum may be 0,129 ⨯ 10⁻⁴ C/kg for X-ray materials and certain other films (see Annex A and Reference [5]).

Some stones or stone aggregates in concrete can emit sufficient radiation (average up to 0,516 ⨯ 10⁻⁴ C/kg/year) to fog very sensitive films after long storage. However, most films and papers are not damaged under normal conditions.

It has been noted by photographers that the X-ray technology used for the inspection of checked baggage at airports uses radiation that fogs many, if not most, unprocessed photographic products. At the time of this revision new technology scanners are being introduced for hand baggage in airports but the effects on photographic film are still being debated.

Government regulations in many countries provide for hand inspection of photographic materials which is strongly recommended, thus avoiding the X-ray inspection. Repeated X-ray exposures can damage higher speed camera films , scientific films, and X-ray films.

Packages of unprocessed silver halide films and papers should be opened only immediately before use. If materials have been stored at low temperatures, a warm-up period is necessary to prevent condensation on film or paper.

The required warm-up period depends on the size of the package, its isolation, the temperature difference between storage and surround, and the dewpoint of the surround. Recommended periods are given in Table 2. All values are for individual packages separated from each other, except for a carton containing 10 35 mm rolls. The length of material on a roll is less important than the thickness and the insulation of the package.

Table 2 — Minimum recommended warm-up times

Rolls, mounted on cores and packed in specially designed containers, shall be stored with the radius of the roll in the horizontal position, in order to avoid the weight of the roll exerting a pressure on the lower part of the roll and thereby causing physical damage.

If sheet materials are unopened and are 203 mm ⨯ 250 mm or larger, they should be stored in the vertical position. If the boxes have been opened, they should be stored in the horizontal position. Smaller boxes of sheet materials can be stored in either way.

Climatic conditions of 20 °C to 24 °C and 40 % to 65 % RH are recommended for handling in laboratories. In printing rooms, the RH should not be too low in order to prevent static discharges and attraction of dirt. In these cases, low humidity can also cause curl and temporary dimensional changes so that proper handling is no longer possible.

Excessive exposure to recommended safelights may degrade the sensitometry of some products. The manufacturer's literature should be consulted for recommended maximum cumulative exposure.

Air-conditioning systems in laboratories should be equipped with suitable dust filters.

Care should be taken in the handling of sheets of film or paper to avoid physical damage caused by sliding materials over one another, kinking, or fingerprinting. Use of lint-free cotton gloves is recommended.

1. 
   (informative)
   
   Background radiation

The radiation dosage of naturally occurring background radiation is expressed in coulomb per kilogram (C/kg), which is a measure of “exposure” and can be applied to X-rays and Υ-rays.

The “gray” (Gy) or micro-gray (µGy) is a measure of “dose” due to any ionizing radiation, so there is no exact equivalence between the two basic units. However, an exposure of 0,002 58 ⨯ 10⁻⁴ C/kg results in a dose of 8,69 µGy in air, or 1 Gy in air results from a 296,70 ⨯ 10⁻⁴ C/kg exposure.

Bibliography

[1] ISO 18906, Imaging materials — Photographic films — Specifications for safety film

[2] ISO 18911, Imaging materials — Processed safety photographic films — Storage practices

[3] ISO 18918, Imaging materials — Processed photographic plates — Storage practices

[4] ISO 18920, Imaging materials — Reflection prints — Storage practices

[5] SULEIMAN O.H., CONWAY B.H., FEWELL T.R., SLAYTON R.J., RUETER F.G., GRAY J. Radiation protection requirements for medical x-ray film. Med. Phys. 1995, 22 (10) pp. 1691–1693