ISO 18905:2002

INTERNATIONAL ISO
STANDARD 18905
First edition
2002-11-01
Imaging materials — Ammonia-processed
diazo photographic film — Specifications
for stability
Matériaux pour l'image — Film photographique diazoïque traité à
l'ammoniac — Spécifications relatives à la stabilité

Reference number
©
ISO 2002
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©  ISO 2002
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ii © ISO 2002 – All rights reserved

Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Film base requirements. 3
5 Processed film requirements. 3
5.1 Safety film. 3
5.2 Tensile properties and loss in tensile properties . 3
6 Requirements for the emulsion and backing layers of processed film. 4
6.1 Layer adhesion. 4
6.2 Blocking. 4
6.3 Binder stability. 4
6.4 Thermal sticking. 4
7 Image stability requirements. 4
7.1 Proper development. 4
7.2 Light-fading. 5
7.3 Dark-ageing. 5
8 Test methods. 5
8.1 Identification of film base. 5
8.2 Accelerated-ageing conditions. 6
8.3 Tensile property test for processed film. 6
8.4 Tape-stripping adhesion test . 7
8.5 Humidity-cycling adhesion test . 7
8.6 Blocking test. 8
8.7 Thermal sticking test . 9
9 Image test methods. 9
9.1 Densitometry. 9
9.2 Proper development test . 9
9.3 Light-fading test. 9
9.4 Dark-ageing test. 10
10 Classification for reporting. 10
Annex A (informative) Numbering system for related International Standards. 11
Annex B (informative) Distinction between film storage (record) copies and work (reference) copies. 13
Annex C (informative) Microfilm image quality. 14
Annex D (informative) Light-fading of diazo images. 16
Bibliography. 17

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.
The main task of technical committees is to prepare International Standards. 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.
ISO 18905 was prepared by Technical Committee ISO/TC 42, Photography.
ISO 18905 cancels and replaces ISO 8225:1995, 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 - 18999 (see annex A).
Annexes A to D of this International Standard are for information only.
iv © ISO 2002 – All rights reserved

Introduction
Since 1930, great advances have been made in the use of photographic films for the preservation of records. The
preservation of records on film by national, state and municipal governments, by banks, insurance companies,
industry and other enterprises has been stimulated by recognition of the resultant economies in storage space,
organization, accessibility and ease of reproduction. The safe-keeping of pictorial film records having legal,
scientific, industrial, medical, historical, military or other values has also become increasingly important.
The use of film for records having long-term values necessitated the development of International Standards to
specify the characteristics of film suitable for this purpose. ISO 18901 specifies the requirements for silver-gelatin
films which are suitable for storage. This International Standard (for diazo film) and ISO 18912 (for vesicular film)
give the requirements for photographic duplicate films suitable for storage.
The term “archival film” has been discontinued and the new concept of “life expectancy” is introduced. Film life is
classified by the LE or life expectancy rating as defined in this International Standard. For example, LE-100
represents film with a life expectancy of 100 years when stored at 21 °C and 50 % RH.
Criteria for properties of LE-10 and LE-100 diazo films are based upon the dark-ageing stability of diazo images.
Different dark-incubation tests are specified for LE-10 and LE-100 films. All other properties and processing
requirements for medium and long-term diazo films are identical.
It is recognized that diazo images may show density changes after exposure to light. However, this International
Standard covers only films used as storage copies, not as work copies (as defined in annex B). The light-fading
requirements specified in this International Standard ensure satisfactory behaviour for storage copies that are not
intended to be subjected to frequent light exposure.
In addition to the characterization of films with respect to their expected storage life, diazo films are also separated
into two classes (A and B) which are dependent upon their intended use. Class A films are those which retain
density in both the visual and actinic region (printing) after storage. Such films can be viewed directly or reprinted
onto ultraviolet (UV)-sensitive materials. However, some diazo films are not intended to be reprinted onto UV-
sensitive materials and require only visual capabilities after storage. Such films are designated as Class B films.
Obviously, both Class A and Class B films can faIl into the LE-10 and LE-100 categories. The requirements for
Class A and Class B films are identical, with the exception of image-stability tests after dark-ageing and after
light-fading.
Everyone concerned with the preservation of records on photographic film should realize that specifying the
chemical and physical characteristics of the material does not, by itself, assure satisfactory behaviour. It is also
essential to provide the correct storage temperature and humidity, as well as protection from the hazards of fire,
water, light and certain atmospheric pollutants. Conditions for the storage of record films are specified in ISO 18902
and ISO 18911.
INTERNATIONAL STANDARD ISO 18905:2002(E)

Imaging materials — Ammonia-processed diazo photographic
film — Specifications for stability
1 Scope
This International Standard establishes specifications for the stability of polyester-base safety film which has an
ammonia-processed diazo photographic image. It is applicable only to diazo photographic films intended for and
used as LE-10 and LE-100 storage copies, which shall be stored in accordance with ISO 18902 and ISO 18911.
This document characterizes only the inherent keeping behaviour of the film. However, the suitability of a film
record after extended storage depends on both the inherent ageing characteristics of the film and the original
image quality. The latter is discussed in annex C.
This International Standard is applicable to photographic film in which the image layer is a discrete layer attached
to a transparent support, and it applies to roll film and sheet film.
This International Standard is not applicable to diazo film records intended and used as “work” or “use” copies as
discussed in annex B.
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.
ISO 5-2:2001, 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 18902:2001, Imaging materials — Processed photographic films, plates and papers — Filing enclosures and
storage containers
ISO 18906:2000, Imaging materials — Photographic films — Specifications for safety film
ISO 18907:2000, Imaging materials — Photographic films and papers — Wedge test for brittleness
ISO 18911:2000, Imaging materials — Processed safety photographic films — Storage practices
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
blocking
sticking together of similar or dissimilar materials in physical contact
3.3
Class A films
films which are usable both visually and for printing onto ultraviolet-sensitive materials
3.4
Class B films
films which are usable visually but do not have any density requirements for printing onto ultraviolet-sensitive
materials
3.5
density
〈optical〉 degree of light absorption, reflection or scattering characteristics of a photographic image, expressed as
the logarithm to the base 10 of the ratio of incident radiant flux to the transmitted, reflected or scattered flux
NOTE See ISO 5-3.
3.5.1
printing density
optical density in which the incident radiant flux has the same spectral energy distribution as the printer light source
and the transmitted density is evaluated by a receiver having the same spectral response as the print material
3.5.2
projection density
optical density of a processed photographic image in which the angular distributions of the incident and transmitted
radiant flux are equal and specified
o
NOTE For microfilm applications, the angular distribution is a nominal half-angle of 6,4 , which corresponds to an f-number
of f /4,5 and simulates a microfilm reader.
3.5.3
visual density
optical density of a processed photographic image in which the incident radiant flux has a spectral energy
distribution as defined in ISO 5-3, and the transmitted or reflected flux is evaluated by the human eye or by a
receiver having the same spectral receiver as the human eye
3.6
emulsion layer(s)
image or image-forming layers(s) of photographic films, papers, and plates
3.7
extended-term storage conditions
storage conditions suitable for the preservation of recorded information having permanent value
3.8
film base
plastic support for the emulsion and backing layers
2 © ISO 2002 – All rights reserved

3.9
LE designation
rating for the “life expectancy” 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.
3.10
life expectancy
LE
length of time that information is predicted to be acceptable in a system after dark storage at 23 °C and 50 % RH
3.11
medium-term storage conditions
storage conditions suitable for the preservation of recorded information for a minimum of 10 years
3.12
polyester base
base for recording materials composed mainly of a polymer of ethylene glycol and terephthalic acid (also referred
to as polyethylene terephthalate), or a polymer of ethylene glycol and 2,6 naphthalene dicarboxylic acid (also
referred to as polyethylene naphthalate)
3.13
poly (ethylene terephthalate) base
polyester base for recording materials composed mainly of a polymer of ethylene glycol and terephthalic acid
3.14
safety photographic film
photographic film which passes the ignition-time test and burning-time test specified in ISO 18906
4 Film base requirements
The base used for record films, as specified in this International Standard, shall be of a safety polyester type and
can be identified by the method described in 8.1.
Films can have a maximum LE rating of 500.
5 Processed film requirements
5.1 Safety film
Film shall meet the requirements specified in ISO 18906.
5.2 Tensile properties and loss in tensile properties
Film samples shall be processed and dried under the conditions used for the film records.
Processed films shall be tested for tensile properties as described in 8.3 and shall have a tensile stress and
elongation at break as specified in Table 1 (unheated film). The loss in tensile properties after accelerated ageing
as described in 8.2 shall not exceed the percentage specified in Table 1 (heated film).
Table 1 — Limits for tensile properties and loss in tensile properties on accelerated ageing
of polyester-base film
Film type Tensile stress at break Elongation at break
Unheated film
Minimum permissible tensile properties 140 MPa 75 %
Heated film
Maximum permissible loss in tensile properties
15 % 30 %
compared with unheated film
6 2
NOTE 1 MPa = 10 N/m
6 Requirements for the emulsion and backing layers of processed film
6.1 Layer adhesion
6.1.1 Tape-stripping adhesion
Processed film shall not show any removal of the emulsion layer or backing layer when tested as described in 8.4.
6.1.2 Humidity-cycling adhesion
The emulsion layer or backing layer of the processed film shall not show separation or cracking that can impair its
intended use when tested as described in 8.5.
6.2 Blocking
Processed film shall show no evidence of blocking (sticking), delamination or surface damage when tested as
described in 8.6. A slight sticking of the film specimens that does not result in physical damage or a change in
gloss of the surface shall be acceptable.
6.3 Binder stability
Processed film shall not exceed a 1 mm increase in brittleness after accelerated ageing as specified in 8.2.
Brittleness shall be determined at 50 % RH and shall be tested in accordance with ISO 18907.
Films shall be tested preferably in low-density areas.
6.4 Thermal sticking
Processed film shall show no evidence of blocking (sticking), delamination or surface damage at high temperature
when tested before and after accelerated ageing as described in 8.2.
Thermal sticking shall be tested as specified in 8.7. A slight sticking of film to glass that does not result in physical
damage shall be acceptable.
7 Image stability requirements
7.1 Proper development
Processed film shall not show a visual transmission density decrease greater than 30 % when tested as specified
in 9.2.
4 © ISO 2002 – All rights reserved

7.2 Light-fading
Low-density and high-density patches of processed film shall be tested in a light-exposure apparatus as described
in 9.3.2.
After testing, the low-density patches shall have a diffuse density of 0,4 or less, and the difference between the
high-density and low-density patches shall be 0,8 or greater (see Table 2).
These density requirements shall apply to both visual and printing densities for Class A films and to visual density
only for Class B films (see annex D). The same density requirements shall apply for both LE-10 and LE-100 films.
7.3 Dark-ageing
Low-density and high-density patches of processed film shall be incubated as specified in 9.4 under the conditions
specified for either LE-10 or LE-100 film. After incubation, the low-density patch shall have a diffuse density of 0,4
or less, and the difference between the high-density and low-density patches shall be 0,8 or greater (see Table 2).
These density requirements shall apply to both visual and printing densities for Class A films and to visual density
only for Class B films.
Table 2 — Limits for the change in diffuse density of the image after accelerated testing
Diazo density levels LE-10 and LE-100 film
Original
Low density 0,10 ± 0,05
High density 1,2 ± 0,1
a
Final
Low density u 0,4
High density — low density W 0,8
a
That is, after the light-fading test (see 9.3) or the dark-ageing test (see 9.4).

8 Test methods
8.1 Identification of film base
Remove all emulsion and backing layers from a sample of the unknown film by scraping and then remove all
sublayers by scraping.
Prepare a specimen of the base material by scuffing the surface with a suitable tool such as a razor blade. The
general procedure is to move the scuffing device back and forth over the specimen manually while exerting a very
slight pressure. This removes the top layer of the base as a very fine dust. Carefully brush this into a mortar.
Mix the specimen with about 100 times its mass of potassium bromide, previously ground to about 75 µm. Prepare
a strip or pellet as described in [1] in the bibliography.
Obtain an infrared absorption curve from the prepared strip or pellet by means of an infrared absorption
spectrometer. By comparing the infrared absorption curve for the unknown with curves for known polymers, the
identity of the unknown can be established (see [2] in the bibliography).
8.2 Accelerated-ageing conditions
Processed film shall be subjected to accelerated-ageing conditions to meet the requirements for a loss in tensile
properties, binder stability and thermal sticking.
o
Test specimens shall be conditioned at (23 ± 1) C and (50 ± 2) % RH for at least 15 h. After conditioning, place the
specimens in a moisture-proof envelope and heat-seal the envelope.
NOTE 1 A suitable moisture-proof envelope is a metal-foil bag that is coated on the inside with polyethylene for heat-sealing.
To prevent sticking between adjacent specimens, it may be necessary to interleave them with polytetrafluoro-
ethylene or uncoated polyester. Ensure a high ratio of film to air volume by squeezing out excess air prior to heat-
sealing. Use a separate envelope for each film sample. Double bagging is recommended to reduce any effects of
pinholes in the envelopes. Heat the envelopes in an oven for 72 h at (100 ± 2) °C.
NOTE 2 Incubation is accomplished in a closed environment to prevent the escape of any acid that may be produced during
incubation. Such acid may catalyse further film-base degradation.
An alternative method of incubating the specimens in a closed environment is by placing them in 25 mm
borosilicate-glass tubes (see [3] in the bibliography). Each tube shall have two flanged sections separated by a
gasket to provide a moisture seal and shall be held together by a metal clamp.
NOTE 3 A suitable inert gasket can be made from polytetrafluoroethylene.
Sufficient film specimens shall be used to provide a high ratio of film to air volume.
NOTE 4 In the text, specimens subjected to these accelerated-ageing conditions are designated “heated film”. Comparison
specimens kept at room conditions are designated “unheated film”.
8.3 Tensile property test for processed film
8.3.1 Specimen preparation
Processed film already in 16 mm format may be tested in this width. In the case of perforated 16 mm film,
specimens shall be cut from the area between the perforations. Film in other sizes shall be cut into sections 15 mm
to 16 mm wide and at least 150 mm long, using a sharp tool that does not nick the edges of the specimen.
Five specimens are required for unheated film and five specimens for heated film. The specimens to be heated and
the control specimens shall be cut alternately and contiguously from a single piece of film.
The thickness of each specimen shall be measured with a suitable gauge to the nearest 0,002 mm and the width to
the nearest 0,1 mm.
8.3.2 Accelerated ageing
Five specimens shall be subjected to accelerated ageing as described in 8.2.
8.3.3 Conditioning
All specimens, both unheated and heated, shall be conditioned at (23 ± 1) °C and at (50 ± 2) % RH for at least
15 h. This can be accomplished by means of an air-conditoned room or a conditioning-air cabinet.
Specimens shall be supported in such a way as to permit free circulation of air around the film. The linear air
velocity shall be at least 150 mm/s.
8.3.4 Procedure
Film specimens shall not be removed from the conditioning atmosphere for testing.
6 © ISO 2002 – All rights reserved

The tensile stress and per cent elongation at break of unheated and heated film specimens shall be tested
alternately by means of a tensile machine, as specified in ISO 527-3. The initial grip separation shall be 100 mm
and the rate of grip separation shall be 50 mm/min.
The tensile stress and per cent elongation at break shall be calculated separately for unheated and heated film.
8.4 Tape-stripping adhesion test
8.4.1 Specimen preparation
Although the dimensions of the processed film specimen are not critical, one dimension shall be at least 150 mm.
Four specimens shall be used for the emulsion surface and four specimens for the backing layer, if present.
8.4.2 Conditioning
Specimens shall be conditioned as described in 8.3.3.
8.4.3 Procedure
Film specimens shall not be removed from the conditioning atmosphere for testing.
1)
Apply a strip of pressure-sensitive, plastic-base adhesive tape about 150 mm long to the surface of the processed
film. Press the tape down with thumb pressure to ensure adequate contact, leaving enough tape at one end to
grasp. No portion of the tape shall extend to the edges of the film specimen or extend to the film perforations.
Hold the specimen firmly on a flat surface and remove the tape rapidly from the film surface. This shall be
accomplished by peeling the tape back on itself and pulling the end so that it is removed from the film at an angle
of approximately 180°. Removal by the tape of any portion of the surface layer on any of the specimens shall be
considered failure.
The result
...