SIST ISO 18912:2011
Imaging materials - Processed vesicular photographic film - Specifications for stability
Imaging materials - Processed vesicular photographic film - Specifications for stability
This International Standard establishes specifications for the stability of polyester-base safety film which has a heat-processed vesicular photographic image formed by nitrogen bubbles. It is applicable only to vesicular photographic film intended 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.
Matériaux pour l'image - Film photographique vésiculaire traité - Spécifications relatives à la stabilité
Upodobitveni materiali - Procesirani vesikularni fotografski film - Specifikacije za stabilnost
Ta mednarodni standard vzpostavlja specifikacije za stabilnost varnostnega filma na poliestrski podlagi s toplotno obdelanimi vesikularnimi fotografskimi slikami, ki nastanejo zaradi dušikovih mehurčkov. Velja le za vesikularni fotografski film, ki je predviden in se uporablja kot kopija za shranjevanje LE-10 in LE-100, shranjena v skladu z ISO 18902 in ISO 18911. Ta dokument označuje le inherentno ohranjevalno obnašanje filma. Primernost filmskega posnetka po daljšem shranjevanju je odvisno od inherentnih značilnosti staranja filma in od izvorne kakovosti slike. Slednje obravnava dodatek C. Ta mednarodni standard velja za fotografski film, pri katerem je plast s sliko ločena plast, pritrjena na prozorno podporo, in velja za film v zvitkih in polah.
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INTERNATIONAL ISO
STANDARD 18912
First edition
2002-11-01
Imaging materials — Processed vesicular
photographic film — Specifications for
stability
Matériaux pour l'image — Film photographique vésiculaire traité —
Spécifications relatives à la stabilité
Reference number
ISO 18912:2002(E)
©
ISO 2002
---------------------- Page: 1 ----------------------
ISO 18912:2002(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2002
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 either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2002 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 18912:2002(E)
Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 2
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 Residual diazonium-salt test. 5
7.3 Light-fading. 5
7.4 Dark-ageing of minimum-density area. 5
7.5 Dark-ageing of vesicular image . 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 . 8
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 Residual diazonium-salt test. 9
9.4 Light-fading test. 10
9.5 Dark-ageing test for the minimum-density area . 10
9.6 Dark-ageing test for the vesicular image. 11
10 Classification for reporting. 11
Annex A (informative) Numbering system for related International Standards. 12
Annex B (informative) Distinction between film storage (record) copies and work (reference) copies. 14
Annex C (informative) Microfilm image quality. 15
Annex D (normative) Effects of heat and pressure. 17
Annex E (informative) Effects of high humidity. 18
Annex F (informative) Light-fading of vesicular images. 19
Annex G (informative) Corrosiveness . 20
Bibliography. 21
© ISO 2002 – All rights reserved iii
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ISO 18912:2002(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 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 18912 was prepared by Technical Committee ISO/TC 42, Photography.
ISO 18912 cancels and replaces the second edition of ISO 9718:1995, 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 G of this International Standard are for information only.
iv © ISO 2002 – All rights reserved
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ISO 18912:2002(E)
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 vesicular film) and ISO 18905 (for diazo 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 vesicular films are based upon the dark-ageing stability of D
min
processed areas. Different dark-incubation tests are specified for LE-10 and LE-100 films. All other properties and
processing requirements for medium and long-term vesicular films are identical.
In addition to tests to ensure that the density of D areas does not increase to unacceptable levels during storage,
min
a test is also specified on high-density areas. This is to guard against the possibility of vesicle (or bubble) collapse
during storage. This test has to be carried out at temperatures below the softening point of the image binder, as
tests above this temperature have no practical meaning (see [1], [2] in the bibliography). However, to give
confidence of acceptable image stability, the permissible density change was set as low as possible, in line with the
measurement error of the densitometer. Both LE-10 and LE-100 vesicular films shall meet the same requirement.
It is recognized that vesicular 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, vesicular 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 vesicular 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.
© ISO 2002 – All rights reserved v
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INTERNATIONAL STANDARD ISO 18912:2002(E)
Imaging materials — Processed vesicular photographic film —
Specifications for stability
1 Scope
This International Standard establishes specifications for the stability of polyester-base safety film which has a
heat-processed vesicular photographic image formed by nitrogen bubbles. It is applicable only to vesicular
photographic film intended 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 vesicular film records intended and used as “work” or “use” copies
as discussed in annex B.
The effects of heat and pressure are discussed in annex D and those of high humidity in annex E.
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
© ISO 2002 – All rights reserved 1
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ISO 18912:2002(E)
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 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
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
2 © ISO 2002 – All rights reserved
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ISO 18912:2002(E)
3.8
film base
plastic support for the emulsion and backing layers
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 the 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 specimens 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).
© ISO 2002 – All rights reserved 3
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ISO 18912:2002(E)
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
15 % 30 %
properties 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 projection density decrease greater than 20 % when tested as specified in 9.2.
4 © ISO 2002 – All rights reserved
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ISO 18912:2002(E)
7.2 Residual diazonium-salt test
Processed film shall not show a printing density decrease greater than 0,1 when tested as specified in 9.3.
7.3 Light-fading
Low-density and high-density patches of processed film shall be tested in a light-exposure apparatus as described
in 9.4.2.
After testing, patches with low-printing and low-projection densities shall have a density of 0,7 or less. The
difference between densities for patches with high and low-printing densities shall be 0,8 or greater and that
between patches with high and low-projection densities shall be 1,4 or greater (see Table 2).
These density requirements shall apply to both projection and printing densities for Class A films and to projection
densities only for Class B films (see annex E). The same density requirements shall apply for both LE-10 and LE-
100 films.
Table 2 — Limits for the change in image density after the light-fading test
Vesicular density levels Printing density Projection density
Original
Low density < 0,4 < 0,4
High density – low density > 0,8 > 1,4
Final
u 0,7 u 0,7
Low density
W 0,8 W 1,4
High density – low density
7.4 Dark-ageing of minimum-density area
Minimum-density patches of processed film shall be incubated as specified in 9.5 using the two conditions specified
for either LE-10 or LE-100 films. After incubation under each of the two conditions, the density patches with low-
printing and low-projection densities shall have a density of 0,6 or less.
These density requirements shall apply to both projection and printing densities for Class A films and to projection
density only for Class B films.
7.5 Dark-ageing of vesicular image
A density patch having a projection density of 2,0 shall be incubated as specified in 9.6. After incubation, the
projection density shall not show a density change greater than ± 0,03.
This density requirement shall apply for both LE-10 and LE-100 films.
8 Test methods
8.1 Identification of film base
Remove all emulsion and backing layers from a specimen of the unknown film by scraping and then remove all
sublayers by scraping.
© ISO 2002 – All rights reserved 5
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ISO 18912:2002(E)
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 [3] in the bibliography.
Obtain an infrared (IR) absorption curve from the prepared strip or pellet by means of an infrared absorption
spectrometer. By comparing the IR absorption curve for the unknown with curves for known polymers, the identity
of the unknown can be established (see [4] 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.
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 specimen. 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 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 [5] 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.
6 © ISO 2002 – All rights reserved
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ISO
...
SLOVENSKI STANDARD
SIST ISO 18912:2011
01-julij-2011
Upodobitveni materiali - Procesirani vesikularni fotografski film - Specifikacije za
stabilnost
Imaging materials - Processed vesicular photographic film - Specifications for stability
Matériaux pour l'image - Film photographique vésiculaire traité - Spécifications relatives
à la stabilité
Ta slovenski standard je istoveten z: ISO 18912:2002
ICS:
37.040.20 )RWRJUDIVNLSDSLUILOPLLQ Photographic paper, films
IRWRJUDIVNHSORãþH)LOPVNL and cartridges
]YLWNL
SIST ISO 18912:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 18912:2011
---------------------- Page: 2 ----------------------
SIST ISO 18912:2011
INTERNATIONAL ISO
STANDARD 18912
First edition
2002-11-01
Imaging materials — Processed vesicular
photographic film — Specifications for
stability
Matériaux pour l'image — Film photographique vésiculaire traité —
Spécifications relatives à la stabilité
Reference number
ISO 18912:2002(E)
©
ISO 2002
---------------------- Page: 3 ----------------------
SIST ISO 18912:2011
ISO 18912:2002(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2002
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 either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2002 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 18912:2011
ISO 18912:2002(E)
Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 2
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 Residual diazonium-salt test. 5
7.3 Light-fading. 5
7.4 Dark-ageing of minimum-density area. 5
7.5 Dark-ageing of vesicular image . 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 . 8
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 Residual diazonium-salt test. 9
9.4 Light-fading test. 10
9.5 Dark-ageing test for the minimum-density area . 10
9.6 Dark-ageing test for the vesicular image. 11
10 Classification for reporting. 11
Annex A (informative) Numbering system for related International Standards. 12
Annex B (informative) Distinction between film storage (record) copies and work (reference) copies. 14
Annex C (informative) Microfilm image quality. 15
Annex D (normative) Effects of heat and pressure. 17
Annex E (informative) Effects of high humidity. 18
Annex F (informative) Light-fading of vesicular images. 19
Annex G (informative) Corrosiveness . 20
Bibliography. 21
© ISO 2002 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 18912:2011
ISO 18912:2002(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 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 18912 was prepared by Technical Committee ISO/TC 42, Photography.
ISO 18912 cancels and replaces the second edition of ISO 9718:1995, 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 G of this International Standard are for information only.
iv © ISO 2002 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 18912:2011
ISO 18912:2002(E)
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 vesicular film) and ISO 18905 (for diazo 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 vesicular films are based upon the dark-ageing stability of D
min
processed areas. Different dark-incubation tests are specified for LE-10 and LE-100 films. All other properties and
processing requirements for medium and long-term vesicular films are identical.
In addition to tests to ensure that the density of D areas does not increase to unacceptable levels during storage,
min
a test is also specified on high-density areas. This is to guard against the possibility of vesicle (or bubble) collapse
during storage. This test has to be carried out at temperatures below the softening point of the image binder, as
tests above this temperature have no practical meaning (see [1], [2] in the bibliography). However, to give
confidence of acceptable image stability, the permissible density change was set as low as possible, in line with the
measurement error of the densitometer. Both LE-10 and LE-100 vesicular films shall meet the same requirement.
It is recognized that vesicular 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, vesicular 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 vesicular 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.
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INTERNATIONAL STANDARD ISO 18912:2002(E)
Imaging materials — Processed vesicular photographic film —
Specifications for stability
1 Scope
This International Standard establishes specifications for the stability of polyester-base safety film which has a
heat-processed vesicular photographic image formed by nitrogen bubbles. It is applicable only to vesicular
photographic film intended 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 vesicular film records intended and used as “work” or “use” copies
as discussed in annex B.
The effects of heat and pressure are discussed in annex D and those of high humidity in annex E.
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
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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 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
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
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3.8
film base
plastic support for the emulsion and backing layers
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 the 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 specimens 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).
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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
15 % 30 %
properties 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 projection density decrease greater than 20 % when tested as specified in 9.2.
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7.2 Residual diazonium-salt test
Processed film shall not show a printing density decrease greater than 0,1 when tested as specified in 9.3.
7.3 Light-fading
Low-density and high-density patches of processed film shall be tested in a light-exposure apparatus as described
in 9.4.2.
After testing, patches with low-printing and low-projection densities shall have a density of 0,7 or less. The
difference between densities for patches with high and low-printing densities shall be 0,8 or greater and that
between patches with high and low-projection densities shall be 1,4 or greater (see Table 2).
These density requirements shall apply to both projection and printing densities for Class A films and to projection
densities only for Class B films (see annex E). The same density requirements shall apply for both LE-10 and LE-
100 films.
Table 2 — Limits for the change in image density after the light-fading test
Vesicular density levels Printing density Projection density
Original
Low density < 0,4 < 0,4
High density – low density > 0,8 > 1,4
Final
u 0,7 u 0,7
Low density
W 0,8 W 1,4
High density – low density
7.4 Dark-ageing of minimum-density area
Minimum-density patches of processed film shall be incubated as specified in 9.5 using the two conditions specified
for either LE-10 or LE-100 films. After incubation under each of the two conditions, the density patches with low-
printing and low-projection densities shall have a density of 0,6 or less.
These density requirements shall apply to both projection and printing densities for Class A films and to projection
density only for Class B films.
7.5 Dark-ageing of vesicular image
A density patch having a projection density of 2,0 shall be incubated as specified in 9.6. After incubation, the
projection density shall not show a density change greater than ± 0,03.
This density requirement shall apply for both LE-10 and LE-100 films.
8 Test methods
8.1 Identification of film base
Remove all emulsion and backing layers from a specimen of the unknown film by scraping and then remove all
sublayers by scraping.
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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 [3] in the bibliography.
Obtain an infrared (IR) absorption curve from the prepared strip or pellet by means of an infrared absorption
spectrometer. By comparing the IR absorption curve for the unknown with curves for known polymers, the identity
of the unknown can be established (see [4] 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.
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 specimen. 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 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 [5] 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
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