SIST ISO 18909:2011
Photography - Processed photographic colour films and paper prints - Methods for measuring image stability
Photography - Processed photographic colour films and paper prints - Methods for measuring image stability
This International Standard describes test methods for determining the long-term dark storage stability of colour photographic images and the colour stability of such images when subjected to certain illuminants at specified temperatures and relative humidities. This International Standard is applicable to colour photographic images made with traditional, continuous-tone photographic materials with images formed with dyes. These images are generated with chromogenic, silver dye-bleach, dye transfer, and dye-diffusion-transfer instant systems. The tests have not been verified for evaluating the stability of colour images produced with dry- and liquid-toner electrophotography, thermal dye transfer (sometimes called dye sublimation), ink jet, pigment-gelatine systems, offset lithography, gravure and related colour imaging systems. This International Standard does not include test procedures for the physical stability of images, supports or binder materials. However, it is recognized that in some instances, physical degradation such as support embrittlement, emulsion cracking or delamination of an image layer from its support, rather than image stability, will determine the useful life of a colour film or print material.
Photographie - Films et papiers photographiques couleur traités - Méthodes de mesure de la stabilité de l'image
Fotografija - Procesirani barvni fotografski filmi in papirni natisi - Metode za merjenje slikovne stabilnosti
Ta mednarodni standard opisuje preskusne metode za določanje dolgotrajne stabilnosti barvnih fotografskih slik pri shranjevanju v temi in barvno stabilnost takih slik pri izpostavitvi določenim svetilom pri določenih temperaturah in relativni vlagi. Ta mednarodni standard velja za barvne fotografske slike, narejene s tradicionalnimi fotografskimi materiali z neprekinjenim tonom s slikami, narejenimi z barvili. Te slike nastanejo s kromogenskimi sistemi, sistemi s srebrovim barvilom in belilom, sistemi s prenosom barvil in polaroidnimi sistemi z difuzijo in prenosom barvil. Preskusi niso preverjeni za vrednotenje stabilnosti barvnih slik, narejenih z elektrofotografijo s suhim in tekočim tonerjem, s sistemom s toplotnim prenosom barvil (včasih imenovanim sublimacija barvil), z brizgalnim tiskalnikom, s sistemom pigmentov in želatine, ofsetno litografijo, gravuro in podobnimi sistemi za barvno upodabljanje. Ta mednarodni standard ne vključuje preskusnih postopkov za fizikalno stabilnost slik, podpor ali vezivnih materialov. Priznava pa se, da v nekaterih primerih fizikalna degradacija, kot je krhkost podpore, pokanje emulzije ali delaminacija plasti slike s podpore, bolj kot stabilnost slike določa življenjsko dobo barvnega filma ali materiala za tiskanje.
General Information
Relations
Buy Standard
Standards Content (Sample)
SLOVENSKI STANDARD
SIST ISO 18909:2011
01-julij-2011
Fotografija - Procesirani barvni fotografski filmi in papirni natisi - Metode za
merjenje slikovne stabilnosti
Photography - Processed photographic colour films and paper prints - Methods for
measuring image stability
Photographie - Films et papiers photographiques couleur traités - Méthodes de mesure
de la stabilité de l'image
Ta slovenski standard je istoveten z: ISO 18909:2006
ICS:
37.040.20 )RWRJUDIVNLSDSLUILOPLLQ Photographic paper, films
IRWRJUDIVNHSORãþH)LOPVNL and cartridges
]YLWNL
SIST ISO 18909:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 18909:2011
---------------------- Page: 2 ----------------------
SIST ISO 18909:2011
INTERNATIONAL ISO
STANDARD 18909
First edition
2006-07-15
Photography — Processed photographic
colour films and paper prints — Methods
for measuring image stability
Photographie — Films et papiers photographiques couleur traités —
Méthodes de mesure de la stabilité de l'image
Reference number
ISO 18909:2006(E)
©
ISO 2006
---------------------- Page: 3 ----------------------
SIST ISO 18909:2011
ISO 18909:2006(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 2006
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.org
Web www.iso.org
Published in Switzerland
ii © ISO 2006 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 18909:2011
ISO 18909:2006(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Test methods — General . 1
3.1 Sensitometric exposure . 1
3.2 Processing. 2
3.3 Densitometry . 3
3.4 Definition of density terms . 3
3.5 Density values to be measured . 3
3.6 Method of correction of density measurements for d changes . 3
min
3.7 Computation of image-life parameters. 8
3.8 Effects of dye fading and stain formation on the printing quality of colour negative
images. 9
4 Test methods — Dark stability . 10
4.1 Introduction . 10
4.2 Test conditions . 10
4.3 Number of specimens . 11
4.4 Test equipment and operation for specimens free-hanging in air . 11
4.5 Test equipment and operation for specimens sealed in moisture-proof bags . 12
4.6 Conditioning and packaging of specimens in moisture-proof bags. 12
4.7 Incubation conditions for specimens sealed in moisture-proof bags . 12
4.8 Computation of dark stability . 12
5 Test methods — Light stability . 12
5.1 Introduction . 12
5.2 Number of specimens . 13
5.3 Irradiance measurements and normalization of test results. 13
5.4 Backing of test specimens during irradiation testing. 13
5.5 Specification for standard window glass.14
5.6 High-intensity filtered xenon arc ID65 illuminant (50 klx to 100 klx) for simulated indoor
indirect daylight through window glass. 14
5.7 Glass-filtered fluorescent room illumination — Cool White fluorescent lamps (80 klx or
lower). 16
5.8 Incandescent tungsten room illumination 3,0 klx – CIE illuminant A spectral distribution. 18
5.9 Simulated outdoor sunlight (xenon arc) 100 klx – CIE D65 spectral distribution. 18
5.10 Intermittent tungsten-halogen lamp slide projection 1 000 klx . 21
5.11 Computation of light stability . 21
6 Test report . 21
6.1 Introduction . 21
6.2 Dark stability tests. 23
6.3 Light stability tests . 24
Annex A (informative) Numbering system for related International Standards. 25
Annex B (informative) A method of interpolation for step wedge exposures. 27
Annex C (informative) Method for power equation d correction of reflection print materials. 28
min
Annex D (informative) Illustration of Arrhenius calculation for dark stability . 33
© ISO 2006 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 18909:2011
ISO 18909:2006(E)
Annex E (informative) The importance of the starting density in the assessment of dye fading and
colour balance changes in light-stability tests. 37
Annex F (informative) Enclosure effects in light-stability tests with prints framed under glass or
plastic sheets. 39
Annex G (informative) Data treatment for the stability of light-exposed colour images. 41
Bibliography . 49
iv © ISO 2006 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 18909:2011
ISO 18909:2006(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 2.
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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 18909 was prepared by Technical Committee ISO/TC 42, Photography.
This first edition cancels and replaces ISO 10977:1993, of which it constitutes a technical revision.
© ISO 2006 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 18909:2011
ISO 18909:2006(E)
Introduction
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 documents, they are assigned a number within the block
from 18900 – 18999 (see Annex A).
This International Standard is divided into two parts. The first covers the methods and procedures for
predicting the long-term, dark storage stability of colour photographic images; the second covers the methods
and procedures for measuring the colour stability of such images when exposed to light of specified intensities
and spectral distribution, at specified temperatures and relative humidities.
Today, the majority of continuous-tone photographs are made with colour photographic materials. The length
of time that such photographs are to be kept can vary from a few days to many hundreds of years and the
importance of image stability can be correspondingly small or great. Often the ultimate use of a particular
photograph may not be known at the outset. Knowledge of the useful life of colour photographs is important to
many users, especially since stability requirements often vary depending upon the application. For museums,
archives, and others responsible for the care of colour photographic materials, an understanding of the
behaviour of these materials under various storage and display conditions is essential if they are to be
preserved in good condition for long periods of time.
Organic cyan, magenta and yellow dyes that are dispersed in transparent binder layers coated on to
transparent or white opaque supports form the images of most modern colour photographs. Colour
photographic dye images typically fade during storage and display; they will usually also change in colour
balance because the three image dyes seldom fade at the same rate. In addition, a yellowish (or occasionally
other colour) stain may form and physical degradation may occur, such as embrittlement and cracking of the
support and image layers. The rate of fading and staining can vary appreciably and is governed principally by
the intrinsic stability of the colour photographic material and by the conditions under which the photograph is
stored and displayed. The quality of chemical processing is another important factor. Post-processing
treatments, such as application of lacquers, plastic laminates and retouching colours, may also affect the
stability of colour materials.
The two main factors that influence storage behaviour, or dark stability, are the temperature and relative
humidity of the air that has access to the photograph. High temperature, particularly in combination with high
relative humidity, will accelerate the chemical reactions that can lead to degradation of one or more of the
image dyes. Low-temperature, low-humidity storage, on the other hand, can greatly prolong the life of
photographic colour images. Other potential causes of image degradation are atmospheric pollutants (such as
oxidizing and reducing gases), micro-organisms and insects.
Primarily the intensity of the illumination, the duration of exposure to light, the spectral distribution of the
illumination, and the ambient environmental conditions influence the stability of colour photographs when
displayed indoors or outdoors. (However, the normally slower dark fading and staining reactions also proceed
during display periods and will contribute to the total change in image quality). Ultraviolet (UV) radiation is
particularly harmful to some types of colour photographs and can cause rapid fading as well as degradation of
plastic layers such as the pigmented polyethylene layer of resin-coated (RC) paper supports.
In practice, colour photographs are stored and displayed under varying combinations of temperature, relative
humidity and illumination, and for different lengths of time. For this reason, it is not possible to precisely
predict the useful life of a given type of photographic material unless the specific conditions of storage and
display are known in advance. Furthermore, the amount of change that is acceptable differs greatly from
viewer to viewer and is influenced by the type of scene and the tonal and colour qualities of the image.
After extensive examination of amateur and professional colour photographs that have suffered varying
degrees of fading or staining, no consensus has been achieved on how much change is acceptable for
various image quality criteria. For this reason, this International Standard does not specify acceptable end-
points for fading and changes in colour balance. Generally, however, the acceptable limits are twice as wide
vi © ISO 2006 – All rights reserved
---------------------- Page: 8 ----------------------
SIST ISO 18909:2011
ISO 18909:2006(E)
for changes in overall image density as for changes in colour balance. For this reason, different criteria have
been used as examples in this International Standard for predicting changes in image density and colour
balance.
Pictorial tests can be helpful in assessing the visual changes that occur in light and dark stability tests, but are
not included in this International Standard because no single scene is representative of the wide variety of
scenes actually encountered in photography.
In dark storage at normal room temperatures, most modern colour films and papers have images that fade
and stain too slowly to allow evaluation of the dark storage stability simply by measuring changes in the
specimens over time. In such cases, too many years would be required to obtain meaningful stability data. It is
possible, however, to assess in a relatively short time the probable long-term fading and staining behaviour at
moderate or low temperatures by means of accelerated ageing tests carried out at high temperatures. The
influence of relative humidity also can be evaluated by conducting the high-temperature tests at two or more
humidity levels.
Similarly, information about the light stability of colour photographs can be obtained from accelerated light-
stability tests. These require special test units equipped with high-intensity light sources in which test strips
can be exposed for days, weeks, months or even years, to produce the desired amount of image fading (or
staining). The temperature of the specimens and their moisture content must be controlled throughout the test
period, and the types of light sources must be chosen to yield data that can be correlated satisfactorily with
those obtained under conditions of normal use.
Accelerated light stability tests for predicting the behaviour of photographic colour images under normal
display conditions may be complicated by reciprocity failure. When applied to light-induced fading and staining
of colour images, reciprocity failure refers to the failure of many dyes to fade, or to form stain. This even
applies when dyes are irradiated with high-intensity versus low-intensity light, even though the total light
exposure (intensity × time) is kept constant through appropriate adjustments in exposure duration (see [1] in
the Bibliography). The extent of dye fading and stain formation can be greater or smaller under accelerated
conditions, depending on the photochemical reactions involved in the dye degradation, the kind of dye
dispersion, the nature of the binder material, and other variables. For example, the supply of oxygen that can
diffuse from the surrounding atmosphere into a photograph's image-containing emulsion layers may be
restricted in an accelerated test (dry gelatin is an excellent oxygen barrier). This may change the rate of dye-
fading relative to that which would occur under normal display conditions. The temperature and moisture
content of the test specimen also influence the magnitude of reciprocity failure. Furthermore, light fading is
influenced by the pattern of irradiation (continuous versus intermittent) as well as by light/dark cycling rates.
For all these reasons, long-term changes in image density, colour balance and stain level can be reasonably
estimated only for conditions similar to those employed in the accelerated tests, or when good correlation has
been confirmed between accelerated tests and actual conditions of use.
In order to establish the validity of the test methods for evaluating the dark and light stability of different types
of photographic colour films and papers, the following product types were selected for the tests:
a) colour negative film with incorporated oil-soluble couplers;
b) colour negative motion picture pre-print and negative films with incorporated oil-soluble couplers;
c) colour reversal film with incorporated oil-soluble couplers;
d) colour reversal film with incorporated Fischer-type couplers;
e) colour reversal film with couplers in the developers;
f) silver dye-bleach film and prints;
g) colour prints with incorporated oil-soluble couplers;
h) colour motion picture print films with incorporated oil-soluble couplers;
© ISO 2006 – All rights reserved vii
---------------------- Page: 9 ----------------------
SIST ISO 18909:2011
ISO 18909:2006(E)
i) colour dye imbibition (dye transfer) prints;
j) integral colour instant print film with dye developers;
k) peel-apart colour instant print film with dye developers;
l) integral colour instant print film with dye releasers.
The results of extensive tests with these materials showed that the methods and procedures of this
International Standard can be used to obtain meaningful information about the long-term dark stability and the
light stability of colour photographs made with a specific product. They also can be used to compare the
stability of colour photographs made with different products and to access the effects of processing variations
or post-processing treatments. The accuracy of predictions made on the basis of such accelerated ageing
tests will depend greatly upon the actual storage or display conditions.
It must also be remembered that density changes induced by the test conditions and measured during and
after the tests include those in the film or paper support and in the various auxiliary layers that may be
included in a particular product. With most materials, however, the major changes occur in the dye image
layers.
Stability when stored in the dark
The tests for predicting the stability of colour photographic images in dark storage are based on an adaptation
of the Arrhenius method described by Bard et al. (see [2] and [3] in the Bibliography) and earlier references by
Arrhenius, Steiger and others (see [4], [5], and [6] in the Bibliography). Although this method is derived from
well-understood and proven theoretical precepts of chemistry, the validity of its application for predicting
changes of photographic images rests on empirical confirmation. Although many chromogenic-type colour
products yield image-fading and staining data in both accelerated and non-accelerated dark ageing tests that
are in good agreement with the Arrhenius relationship, some other types of products do not.
NOTE For example, integral-type instant colour print materials often exhibit atypical staining at elevated
temperatures; treatment of some chromogenic materials at temperatures above 80 °C and 60 % RH may cause loss of
incorporated high-boiling solvents and abnormal image degradation; and the dyes of silver dye-bleach images
deaggregate at combinations of very high temperature and high relative humidity, causing abnormal changes in colour
balance and saturation (see [7] in the Bibliography). In general, photographic materials tend to undergo dramatic changes
at relative humidities above 60 % (especially at the high temperatures employed in accelerated tests) owing to changes in
the physical properties of gelatine.
Stability when exposed to light
The methods of testing light stability in this International Standard are based on the concept that increasing
the light intensity without changing the spectral distribution of the illuminant or the ambient temperature and
relative humidity should produce a proportional increase in the photochemical reactions that occur at typical
viewing or display conditions, without introducing any undesirable side effects.
However, because of reciprocity failures that are discussed in this Introduction, this assumption does not
always apply. Thus, the accelerated light stability test methods described in this International Standard are
valid at the specified accelerated test conditions, but may not reliably predict the behaviours of a given product
in long-term display under normal conditions.
Translucent print materials, designed for viewing by either reflected or transmitted light (or a combination of
reflected and transmitted light), shall be evaluated as transparencies or as reflection prints, depending on how
they will be used. Data shall be reported for each condition of intended use.
This International Standard does not specify which of the several light stability tests is the most important for
any particular product.
viii © ISO 2006 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 18909:2011
INTERNATIONAL STANDARD ISO 18909:2006(E)
Photography — Processed photographic colour films and paper
prints — Methods for measuring image stability
1 Scope
This International Standard describes test methods for determining the long-term dark storage stability of
colour photographic images and the colour stability of such images when subjected to certain illuminants at
specified temperatures and relative humidities.
This International Standard is applicable to colour photographic images made with traditional, continuous-tone
photographic materials with images formed with dyes. These images are generated with chromogenic, silver
dye-bleach, dye transfer, and dye-diffusion-transfer instant systems. The tests have not been verified for
evaluating the stability of colour images produced with dry- and liquid-toner electrophotography, thermal dye
transfer (sometimes called dye sublimation), ink jet, pigment-gelatine systems, offset lithography, gravure and
related colour imaging systems.
This International Standard does not include test procedures for the physical stability of images, supports or
binder materials. However, it is recognized that in some instances, physical degradation such as support
embrittlement, emulsion cracking or delamination of an image layer from its support, rather than image
stability, will determine the useful life of a colour film or print material.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
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 5-4:1995, Photography — Density measurements — Part 4: Geometric conditions for reflection density
ISO 18911-2000, Imaging materials — Processed safety photographic films — Storage practices
3 Test methods — General
3.1 Sensitometric exposure
The photographic material shall be exposed and processed in accordance with the manufacturer’s
recommendations to obtain areas (patches) of uniform density at least 5 mm × 5 mm. This International
Standard requires measuring the changes in colour densities in minimum density areas (d ) and at a density
min
of 1,0 ± 0,05 above d . These changes are to be monitored in neutral areas, i.e. where the initial red, green
min
and blue densities are approximately equal (above their respective d ), as well as in areas selectively
min
© ISO 2006 – All rights reserved 1
---------------------- Page: 11 ----------------------
SIST ISO 18909:2011
ISO 18909:2006(E)
1)
exposed to produce the purest possible cyan, magenta and yellow dye scales . These shall be made with the
aid of appropriate filters (see Table 1).
The desired density may be obtained from a single precise exposure or from a continuous wedge exposure.
Alternatively, if it is more convenient (e.g. with automated densitometry), the starting densities of 1,0 above
d may be interpolated from other densities (one way to do this is described in Annex B).
min
Table 1 — Suitable filters for exposing test specimens
Filters to generate
b c
a (e.g. Kodak Wratten filters or Fuji filters )
Type of material
Cyan dye Magenta dye Yellow dye
Minus red Minus green Minus blue
Wratten 32
Reversal and direct positive
Wratten 44 Wratten 12
Fuji SP-4
Fuji SP-5 Fuji SC-50 or SC-52
or SP-12
Red Green Blue
Negative working
Wratten 29 Wratten 99 Wratten 47B
Fuji SC-62 Fuji BPN-55 Fuji BPB-42
a
If materials to be tested have unusual spectral sensitivity characteristics, consult the manufacturer for filter recommendations.
b
Kodak Filters for Scientific and Technical Uses, Kodak Publication No. B-3, Eastman Kodak Company, Rochester, New York,
USA; 1985. This information is given for the convenience of users of this International Standard and does not constitute an
endorsement by ISO of the product named. Equivalent products may be used if they can be shown to lead to the same results.
c
Fujifilm Filter “Optical," Fuji Photo Film Co., Ltd., Tokyo, Japan; 1993. This information is given for the convenience of users of
this International Standard and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if
they can be shown to lead to the same results.
3.2 Processing
The sensitometrically exposed specimens shall be processed using the processing system of primary interest.
The processing chemicals and processing procedure can have a significant effect on the dark-keeping and/or
light-keeping stability of a colour photographic material. For example, a chromogenic colour negative print
paper processed in a washless or non-plumbed system with a stabilizer rinse bath instead of a water wash
probably has stability characte
...
INTERNATIONAL ISO
STANDARD 18909
First edition
2006-07-15
Photography — Processed photographic
colour films and paper prints — Methods
for measuring image stability
Photographie — Films et papiers photographiques couleur traités —
Méthodes de mesure de la stabilité de l'image
Reference number
ISO 18909:2006(E)
©
ISO 2006
---------------------- Page: 1 ----------------------
ISO 18909:2006(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 2006
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.org
Web www.iso.org
Published in Switzerland
ii © ISO 2006 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 18909:2006(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Test methods — General . 1
3.1 Sensitometric exposure . 1
3.2 Processing. 2
3.3 Densitometry . 3
3.4 Definition of density terms . 3
3.5 Density values to be measured . 3
3.6 Method of correction of density measurements for d changes . 3
min
3.7 Computation of image-life parameters. 8
3.8 Effects of dye fading and stain formation on the printing quality of colour negative
images. 9
4 Test methods — Dark stability . 10
4.1 Introduction . 10
4.2 Test conditions . 10
4.3 Number of specimens . 11
4.4 Test equipment and operation for specimens free-hanging in air . 11
4.5 Test equipment and operation for specimens sealed in moisture-proof bags . 12
4.6 Conditioning and packaging of specimens in moisture-proof bags. 12
4.7 Incubation conditions for specimens sealed in moisture-proof bags . 12
4.8 Computation of dark stability . 12
5 Test methods — Light stability . 12
5.1 Introduction . 12
5.2 Number of specimens . 13
5.3 Irradiance measurements and normalization of test results. 13
5.4 Backing of test specimens during irradiation testing. 13
5.5 Specification for standard window glass.14
5.6 High-intensity filtered xenon arc ID65 illuminant (50 klx to 100 klx) for simulated indoor
indirect daylight through window glass. 14
5.7 Glass-filtered fluorescent room illumination — Cool White fluorescent lamps (80 klx or
lower). 16
5.8 Incandescent tungsten room illumination 3,0 klx – CIE illuminant A spectral distribution. 18
5.9 Simulated outdoor sunlight (xenon arc) 100 klx – CIE D65 spectral distribution. 18
5.10 Intermittent tungsten-halogen lamp slide projection 1 000 klx . 21
5.11 Computation of light stability . 21
6 Test report . 21
6.1 Introduction . 21
6.2 Dark stability tests. 23
6.3 Light stability tests . 24
Annex A (informative) Numbering system for related International Standards. 25
Annex B (informative) A method of interpolation for step wedge exposures. 27
Annex C (informative) Method for power equation d correction of reflection print materials. 28
min
Annex D (informative) Illustration of Arrhenius calculation for dark stability . 33
© ISO 2006 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 18909:2006(E)
Annex E (informative) The importance of the starting density in the assessment of dye fading and
colour balance changes in light-stability tests. 37
Annex F (informative) Enclosure effects in light-stability tests with prints framed under glass or
plastic sheets. 39
Annex G (informative) Data treatment for the stability of light-exposed colour images. 41
Bibliography . 49
iv © ISO 2006 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 18909:2006(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 2.
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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 18909 was prepared by Technical Committee ISO/TC 42, Photography.
This first edition cancels and replaces ISO 10977:1993, of which it constitutes a technical revision.
© ISO 2006 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 18909:2006(E)
Introduction
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 documents, they are assigned a number within the block
from 18900 – 18999 (see Annex A).
This International Standard is divided into two parts. The first covers the methods and procedures for
predicting the long-term, dark storage stability of colour photographic images; the second covers the methods
and procedures for measuring the colour stability of such images when exposed to light of specified intensities
and spectral distribution, at specified temperatures and relative humidities.
Today, the majority of continuous-tone photographs are made with colour photographic materials. The length
of time that such photographs are to be kept can vary from a few days to many hundreds of years and the
importance of image stability can be correspondingly small or great. Often the ultimate use of a particular
photograph may not be known at the outset. Knowledge of the useful life of colour photographs is important to
many users, especially since stability requirements often vary depending upon the application. For museums,
archives, and others responsible for the care of colour photographic materials, an understanding of the
behaviour of these materials under various storage and display conditions is essential if they are to be
preserved in good condition for long periods of time.
Organic cyan, magenta and yellow dyes that are dispersed in transparent binder layers coated on to
transparent or white opaque supports form the images of most modern colour photographs. Colour
photographic dye images typically fade during storage and display; they will usually also change in colour
balance because the three image dyes seldom fade at the same rate. In addition, a yellowish (or occasionally
other colour) stain may form and physical degradation may occur, such as embrittlement and cracking of the
support and image layers. The rate of fading and staining can vary appreciably and is governed principally by
the intrinsic stability of the colour photographic material and by the conditions under which the photograph is
stored and displayed. The quality of chemical processing is another important factor. Post-processing
treatments, such as application of lacquers, plastic laminates and retouching colours, may also affect the
stability of colour materials.
The two main factors that influence storage behaviour, or dark stability, are the temperature and relative
humidity of the air that has access to the photograph. High temperature, particularly in combination with high
relative humidity, will accelerate the chemical reactions that can lead to degradation of one or more of the
image dyes. Low-temperature, low-humidity storage, on the other hand, can greatly prolong the life of
photographic colour images. Other potential causes of image degradation are atmospheric pollutants (such as
oxidizing and reducing gases), micro-organisms and insects.
Primarily the intensity of the illumination, the duration of exposure to light, the spectral distribution of the
illumination, and the ambient environmental conditions influence the stability of colour photographs when
displayed indoors or outdoors. (However, the normally slower dark fading and staining reactions also proceed
during display periods and will contribute to the total change in image quality). Ultraviolet (UV) radiation is
particularly harmful to some types of colour photographs and can cause rapid fading as well as degradation of
plastic layers such as the pigmented polyethylene layer of resin-coated (RC) paper supports.
In practice, colour photographs are stored and displayed under varying combinations of temperature, relative
humidity and illumination, and for different lengths of time. For this reason, it is not possible to precisely
predict the useful life of a given type of photographic material unless the specific conditions of storage and
display are known in advance. Furthermore, the amount of change that is acceptable differs greatly from
viewer to viewer and is influenced by the type of scene and the tonal and colour qualities of the image.
After extensive examination of amateur and professional colour photographs that have suffered varying
degrees of fading or staining, no consensus has been achieved on how much change is acceptable for
various image quality criteria. For this reason, this International Standard does not specify acceptable end-
points for fading and changes in colour balance. Generally, however, the acceptable limits are twice as wide
vi © ISO 2006 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 18909:2006(E)
for changes in overall image density as for changes in colour balance. For this reason, different criteria have
been used as examples in this International Standard for predicting changes in image density and colour
balance.
Pictorial tests can be helpful in assessing the visual changes that occur in light and dark stability tests, but are
not included in this International Standard because no single scene is representative of the wide variety of
scenes actually encountered in photography.
In dark storage at normal room temperatures, most modern colour films and papers have images that fade
and stain too slowly to allow evaluation of the dark storage stability simply by measuring changes in the
specimens over time. In such cases, too many years would be required to obtain meaningful stability data. It is
possible, however, to assess in a relatively short time the probable long-term fading and staining behaviour at
moderate or low temperatures by means of accelerated ageing tests carried out at high temperatures. The
influence of relative humidity also can be evaluated by conducting the high-temperature tests at two or more
humidity levels.
Similarly, information about the light stability of colour photographs can be obtained from accelerated light-
stability tests. These require special test units equipped with high-intensity light sources in which test strips
can be exposed for days, weeks, months or even years, to produce the desired amount of image fading (or
staining). The temperature of the specimens and their moisture content must be controlled throughout the test
period, and the types of light sources must be chosen to yield data that can be correlated satisfactorily with
those obtained under conditions of normal use.
Accelerated light stability tests for predicting the behaviour of photographic colour images under normal
display conditions may be complicated by reciprocity failure. When applied to light-induced fading and staining
of colour images, reciprocity failure refers to the failure of many dyes to fade, or to form stain. This even
applies when dyes are irradiated with high-intensity versus low-intensity light, even though the total light
exposure (intensity × time) is kept constant through appropriate adjustments in exposure duration (see [1] in
the Bibliography). The extent of dye fading and stain formation can be greater or smaller under accelerated
conditions, depending on the photochemical reactions involved in the dye degradation, the kind of dye
dispersion, the nature of the binder material, and other variables. For example, the supply of oxygen that can
diffuse from the surrounding atmosphere into a photograph's image-containing emulsion layers may be
restricted in an accelerated test (dry gelatin is an excellent oxygen barrier). This may change the rate of dye-
fading relative to that which would occur under normal display conditions. The temperature and moisture
content of the test specimen also influence the magnitude of reciprocity failure. Furthermore, light fading is
influenced by the pattern of irradiation (continuous versus intermittent) as well as by light/dark cycling rates.
For all these reasons, long-term changes in image density, colour balance and stain level can be reasonably
estimated only for conditions similar to those employed in the accelerated tests, or when good correlation has
been confirmed between accelerated tests and actual conditions of use.
In order to establish the validity of the test methods for evaluating the dark and light stability of different types
of photographic colour films and papers, the following product types were selected for the tests:
a) colour negative film with incorporated oil-soluble couplers;
b) colour negative motion picture pre-print and negative films with incorporated oil-soluble couplers;
c) colour reversal film with incorporated oil-soluble couplers;
d) colour reversal film with incorporated Fischer-type couplers;
e) colour reversal film with couplers in the developers;
f) silver dye-bleach film and prints;
g) colour prints with incorporated oil-soluble couplers;
h) colour motion picture print films with incorporated oil-soluble couplers;
© ISO 2006 – All rights reserved vii
---------------------- Page: 7 ----------------------
ISO 18909:2006(E)
i) colour dye imbibition (dye transfer) prints;
j) integral colour instant print film with dye developers;
k) peel-apart colour instant print film with dye developers;
l) integral colour instant print film with dye releasers.
The results of extensive tests with these materials showed that the methods and procedures of this
International Standard can be used to obtain meaningful information about the long-term dark stability and the
light stability of colour photographs made with a specific product. They also can be used to compare the
stability of colour photographs made with different products and to access the effects of processing variations
or post-processing treatments. The accuracy of predictions made on the basis of such accelerated ageing
tests will depend greatly upon the actual storage or display conditions.
It must also be remembered that density changes induced by the test conditions and measured during and
after the tests include those in the film or paper support and in the various auxiliary layers that may be
included in a particular product. With most materials, however, the major changes occur in the dye image
layers.
Stability when stored in the dark
The tests for predicting the stability of colour photographic images in dark storage are based on an adaptation
of the Arrhenius method described by Bard et al. (see [2] and [3] in the Bibliography) and earlier references by
Arrhenius, Steiger and others (see [4], [5], and [6] in the Bibliography). Although this method is derived from
well-understood and proven theoretical precepts of chemistry, the validity of its application for predicting
changes of photographic images rests on empirical confirmation. Although many chromogenic-type colour
products yield image-fading and staining data in both accelerated and non-accelerated dark ageing tests that
are in good agreement with the Arrhenius relationship, some other types of products do not.
NOTE For example, integral-type instant colour print materials often exhibit atypical staining at elevated
temperatures; treatment of some chromogenic materials at temperatures above 80 °C and 60 % RH may cause loss of
incorporated high-boiling solvents and abnormal image degradation; and the dyes of silver dye-bleach images
deaggregate at combinations of very high temperature and high relative humidity, causing abnormal changes in colour
balance and saturation (see [7] in the Bibliography). In general, photographic materials tend to undergo dramatic changes
at relative humidities above 60 % (especially at the high temperatures employed in accelerated tests) owing to changes in
the physical properties of gelatine.
Stability when exposed to light
The methods of testing light stability in this International Standard are based on the concept that increasing
the light intensity without changing the spectral distribution of the illuminant or the ambient temperature and
relative humidity should produce a proportional increase in the photochemical reactions that occur at typical
viewing or display conditions, without introducing any undesirable side effects.
However, because of reciprocity failures that are discussed in this Introduction, this assumption does not
always apply. Thus, the accelerated light stability test methods described in this International Standard are
valid at the specified accelerated test conditions, but may not reliably predict the behaviours of a given product
in long-term display under normal conditions.
Translucent print materials, designed for viewing by either reflected or transmitted light (or a combination of
reflected and transmitted light), shall be evaluated as transparencies or as reflection prints, depending on how
they will be used. Data shall be reported for each condition of intended use.
This International Standard does not specify which of the several light stability tests is the most important for
any particular product.
viii © ISO 2006 – All rights reserved
---------------------- Page: 8 ----------------------
INTERNATIONAL STANDARD ISO 18909:2006(E)
Photography — Processed photographic colour films and paper
prints — Methods for measuring image stability
1 Scope
This International Standard describes test methods for determining the long-term dark storage stability of
colour photographic images and the colour stability of such images when subjected to certain illuminants at
specified temperatures and relative humidities.
This International Standard is applicable to colour photographic images made with traditional, continuous-tone
photographic materials with images formed with dyes. These images are generated with chromogenic, silver
dye-bleach, dye transfer, and dye-diffusion-transfer instant systems. The tests have not been verified for
evaluating the stability of colour images produced with dry- and liquid-toner electrophotography, thermal dye
transfer (sometimes called dye sublimation), ink jet, pigment-gelatine systems, offset lithography, gravure and
related colour imaging systems.
This International Standard does not include test procedures for the physical stability of images, supports or
binder materials. However, it is recognized that in some instances, physical degradation such as support
embrittlement, emulsion cracking or delamination of an image layer from its support, rather than image
stability, will determine the useful life of a colour film or print material.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
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 5-4:1995, Photography — Density measurements — Part 4: Geometric conditions for reflection density
ISO 18911-2000, Imaging materials — Processed safety photographic films — Storage practices
3 Test methods — General
3.1 Sensitometric exposure
The photographic material shall be exposed and processed in accordance with the manufacturer’s
recommendations to obtain areas (patches) of uniform density at least 5 mm × 5 mm. This International
Standard requires measuring the changes in colour densities in minimum density areas (d ) and at a density
min
of 1,0 ± 0,05 above d . These changes are to be monitored in neutral areas, i.e. where the initial red, green
min
and blue densities are approximately equal (above their respective d ), as well as in areas selectively
min
© ISO 2006 – All rights reserved 1
---------------------- Page: 9 ----------------------
ISO 18909:2006(E)
1)
exposed to produce the purest possible cyan, magenta and yellow dye scales . These shall be made with the
aid of appropriate filters (see Table 1).
The desired density may be obtained from a single precise exposure or from a continuous wedge exposure.
Alternatively, if it is more convenient (e.g. with automated densitometry), the starting densities of 1,0 above
d may be interpolated from other densities (one way to do this is described in Annex B).
min
Table 1 — Suitable filters for exposing test specimens
Filters to generate
b c
a (e.g. Kodak Wratten filters or Fuji filters )
Type of material
Cyan dye Magenta dye Yellow dye
Minus red Minus green Minus blue
Wratten 32
Reversal and direct positive
Wratten 44 Wratten 12
Fuji SP-4
Fuji SP-5 Fuji SC-50 or SC-52
or SP-12
Red Green Blue
Negative working
Wratten 29 Wratten 99 Wratten 47B
Fuji SC-62 Fuji BPN-55 Fuji BPB-42
a
If materials to be tested have unusual spectral sensitivity characteristics, consult the manufacturer for filter recommendations.
b
Kodak Filters for Scientific and Technical Uses, Kodak Publication No. B-3, Eastman Kodak Company, Rochester, New York,
USA; 1985. This information is given for the convenience of users of this International Standard and does not constitute an
endorsement by ISO of the product named. Equivalent products may be used if they can be shown to lead to the same results.
c
Fujifilm Filter “Optical," Fuji Photo Film Co., Ltd., Tokyo, Japan; 1993. This information is given for the convenience of users of
this International Standard and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if
they can be shown to lead to the same results.
3.2 Processing
The sensitometrically exposed specimens shall be processed using the processing system of primary interest.
The processing chemicals and processing procedure can have a significant effect on the dark-keeping and/or
light-keeping stability of a colour photographic material. For example, a chromogenic colour negative print
paper processed in a washless or non-plumbed system with a stabilizer rinse bath instead of a water wash
probably has stability characteristics that are different from the same colour paper processed in a conventional
chemistry and a final water wash. Therefore, the specific processing chemicals and procedure shall be listed
along with the name of the colour product in any reference to the test results.
Stability data obtained from a colour material processed in certain processing chemicals shall not be applied
to the colour material processed in different chemicals, or using a different processing procedure. Likewise,
data obtained from test specimens shall not be applied to colour materials that have been subjected to post-
processing treatments (e.g. application of lacquers, plastic laminates or retouching colours) that differ from the
treatments given to the test specimens.
1) Because of optical or chemical interactions, a neutral patch or a patch with a colour composed of a mixture of two
dyes, e.g. red, green or blue, often exhibit stability effects that are different from pure cyan, magenta or yellow dy
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.