ISO 18919:1999
(Main)Imaging materials — Thermally processed silver microfilm — Specifications for stability
Imaging materials — Thermally processed silver microfilm — Specifications for stability
This International Standard establishes specifications for the stability of photographic films intended for storage of records; specifically, microfilms with a base of safety polyester [poly(ethylene terephthalate)] having predominantly silver behenate salts dispersed in nongelatinous emulsions, and thermally processed to produce a black-and-white silver image. This International Standard applies to thermally processed silver (TPS) microfilms having ultrasonic or dielectric (induction-heated) splices. It does not cover films with splices made by means of adhesive tape. This International Standard does not cover other types of black-and-white TPS films, black-and-white paper, colour images and colour prints that are produced with thermally processed silver behenate systems. It does not apply to films to which lacquers have been applied. It also does not apply to conventional black-and-white silver images that are produced by wet processing of silvergelatin films (see ISO 10602).
Matériaux pour image — Microfilm à l'argent traité thermiquement — Spécifications pour la stabilité
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 18919
First edition
1999-08-01
Imaging materials — Thermally processed
silver microfilm — Specifications for
stability
Matériaux pour image — Microfilm à l'argent traité thermiquement —
Spécifications pour la stabilité
A
Reference number
Contents
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Safety and hazards .3
5 Requirements for the film base .3
6 Requirements for the thermally processed silver microfilm.3
7 Requirements for the emulsion and backing layers of thermally processed silver microfilm .4
8 Requirements for image stability .5
9 Test methods.5
10 Storage of films.11
Annex A (normative) Preparation of standard solution of tetrabutylammonium hydroxide.12
Annex B (informative) Numbering system for related International Standards.14
Annex C (informative) Effect of residual compounds on the thermally processed silver image.15
Annex D (informative) Accelerated image stability test for thermally processed silver microfilms.16
Annex E (informative) Bibliography .19
© ISO 1999
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
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.
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 18919 was prepared by Technical Committee ISO/TC 42, Photography.
This International Standard is one of a series of 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 B).
Annex A forms an integral part of this International Standard. Annexes B, C, D and E are for information only.
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© ISO
Introduction
Thermally processed silver (TPS) films are used widely for computer-output microfilming (COM) and for document
recording. This International Standard is intended to provide the desired information on the stability of IPS images
as well as other relevant properties of TPS microfilms. The basic elements of the TPS imaging process are also
reviewed.
The first commercial TPS imaging product for the micrographic market was a photothermographic paper, called dry
silver paper. It was introduced in 1964. This paper was designed for exposure by projection and for processing with
a heated drum in a combination reader-printer processor. A TPS film based on this technology, but adopted for
COM recording, followed in 1968. Since then, several other TPS-type films for computer-output and source-
document microfilming have been introduced by several manufacturers. Special TPS products for other imaging
applications have also been developed, including films for graphic arts and for duplication of aerial photographs,
radiographic applications, as well as for line recording and remote sensing systems using laser beam and cathode-
ray tube (CRT) imaging devices. However, these special products are not covered by this International Standard. It
covers only the currently available TPS microfilms based on the present state of photothermographic technology.
The unique feature of TPS microfilm and its major advantage over conventional silver-gelatin products is its one-
step, dry processing method. Another notable difference is that the image-forming components and, therefore, also
the final silver image are dispersed in a non-gelatin binder, primarily [poly(vinylbutyral)]. This renders them inert to
moisture and its deleterious effects. The support of TPS films is normal, photographic grade PET [poly(ethylene
terephthalate)] safety film ([1], [2], [3], [4], [5], [6]).
In most contemporary TPS films, the metallic silver that forms the image is contributed by light-insensitive silver
behenate salts that react with an incorporated reducing agent during heat development. This reaction is catalyzed
by latent image silver formed during light exposure of silver halide crystals that are also incorporated in the imaging
layer. Accordingly, the reaction occurs at a much higher rate in exposed than in unexposed areas, akin to the
different rate of reduction of exposed and unexposed silver halide crystals by a chemical developer in a
conventional photographic system.
Two important advantages offered by the TPS process include rapid, relatively simple and convenient dry
processing and inertness to oxidation of silver images. These images are relatively stable, based on behaviour
under normal user and storage conditions as well as on accelerated ageing studies. ([7], [8], [9]). Since TPS films
are heat-processed by raising the temperature to between 119 °C and 125 °C, which is well above any expected
use and recommended storage temperatures, no chemical fixation is required. Hence, TPS films do not fall within
the provisions of ISO 10602 that apply to chemical fixation.
These attractive features should be weighed against the disadvantage that, in the TPS process, the residual image-
forming components are not removed during processing. Therefore, the potential for formation of excessive fog
exists throughout the life of the record; such fog may render the image unusable. This may occur during dark
storage at elevated temperatures, or on prolonged exposure to ambient illumination, or especially on excessive
exposure to light and heat in a reader-printer or to heat generated by a nearby fire. In the case of fire, the
temperature inside a "fireproof" vault or safe can also rise to cause image degradation. Concerns with these
possible causes of degradation have led to the adoption of considerably lower life expectancy ratings of TPS films in
these specifications than indicated by accelerated ageing studies.
This International Standard includes all the requirements for the stability of wet-processed silver-gelatin films on
safety bases, set forth in ISO 10602. They also include special thermal requirements applicable to TPS films and
the requirement of at least ten duplications with a high-intensity mercury vapour lamp, stipulated for diazo and
vesicular films. A few other relevant requirements for thermally processed vesicular films (ISO 9718) and ammonia
processed diazo films (ISO 8225) are also included.
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INTERNATIONAL STANDARD © ISO ISO 18919:1999(E)
Imaging materials — Thermally processed silver microfilm —
Specifications for stability
1 Scope
This International Standard establishes specifications for the stability of photographic films intended for storage of
records; specifically, microfilms with a base of safety polyester [poly(ethylene terephthalate)] having predominantly
silver behenate salts dispersed in nongelatinous emulsions, and thermally processed to produce a black-and-white
silver image.
This International Standard applies to thermally processed silver (TPS) microfilms having ultrasonic or dielectric
(induction-heated) splices. It does not cover films with splices made by means of adhesive tape.
This International Standard does not cover other types of black-and-white TPS films, black-and-white paper, colour
images and colour prints that are produced with thermally processed silver behenate systems.
It does not apply to films to which lacquers have been applied.
It also does not apply to conventional black-and-white silver images that are produced by wet processing of silver-
gelatin films (see ISO 10602).
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 5-2:1991, Photography — Density measurements — Part 2: Geometric conditions for transmission density.
ISO 5-3:1995, Photography — Density measurements — Part 3: Spectral conditions.
ISO 527-3:1995, Plastics — Determination of tensile properties — Part 3: Test conditions for films and sheets.
ISO 543:1990, Photography — Photographic films — Specifications for safety film.
ISO 6077:1993, Photography — Photographic films and papers — Wedge test for brittleness.
ISO 7565:1993, Micrographics — Readers for transparent microforms — Measurement of characteristics.
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.
3 Terms and definitions
For the purposes of this International Standard, the following definitions apply.
© ISO
3.1
archival medium
recording material that can be expected to retain information for ever so that it 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
life expectancy
LE
length of time that information is predicted to be retrievable in a system under extended-term storage conditions
NOTE However, the actual useful life of film is very dependent upon the existing storage conditions (for example, see
[19] [21]
ISO 5466 and ISO 10214) .
3.3
LE designation
rating for the "life expectancy" of recording materials and associated retrieval systems; 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 under extended-term storage conditions
NOTE For example, LE-100 indicates that information can be retrieved for at least 100 years storage.
3.4
extended-term storage conditions
storage conditions suitable for the preservation of recorded information having a permanent value
3.5
medium-term storage conditions
storage conditions suitable for the preservation of recorded information for a minimum of ten years
3.6
film base
plastic support for the emulsion and backing layers
3.7
emulsion layer(s)
image or image-forming layer(s) of photographic films, papers and plates
3.8
non-curl backing layer
layer, usually made of gelatin, applied to the side of the film base opposite to that of the emulsion layer, for the
purpose of preventing curl
NOTE 1 It is comparable to the emulsion layer in thickness and is not removed in processing.
NOTE 2 Antihalation or other layers removed are excluded from this definition.
3.9
safety photographic film
photographic film which passes the ignition time test and burning time test as specified in ISO 543
3.10
safety poly(ethylene terephthalate) base
polyester film base composed mainly of a polymer of ethylene glycol and terephthalic acid
© ISO
4 Safety and hazards
4.1 Hazard warnings
Some of the chemicals specified in the test procedures are caustic, toxic or otherwise hazardous. Safe laboratory
practice for the handling of chemicals requires the use of safety glasses or goggles, rubber gloves and other
protective apparel such as face-masks or aprons where appropriate. Specific danger notices are given in the text for
particularly dangerous materials, but normal precautions are required during the performance of any chemical
procedures at all times. The first time that a hazardous material is noted in the test procedure section, the hazard is
indicated by the word "DANGER" followed by a symbol consisting of angle brackets " " containing a letter which
designates the specific hazard. A double bracket " " is used for particularly perilous situations. In subsequent
statements involving handling of these hazardous materials, only the hazard symbol consisting of the brackets and
letter(s) is displayed. Furthermore, for a given material, the hazard symbol is used only once in a single paragraph.
Detailed warning
...
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