SIST ISO 18903:2011
Imaging materials - Films and paper - Determination of dimensional change
Imaging materials - Films and paper - Determination of dimensional change
This International Standard specifies a method for determining the dimensional change of photographic films and papers caused by: . variations in equilibrium moisture content due to change in the relative humidity (RH) of the atmosphere (humidity coefficient of expansion); - change in temperature (thermal coefficient of expansion); - processing; - ageing. This International Standard deals with the moisture content and thermal history of the specimens before measurement, the atmospheric conditions during measurement, and the treatment of the data. It does not describe the various experimental techniques used to make the measurements.
Matériaux pour l'image - Films et papiers - Détermination des variations dimensionnelles
Upodobitveni materiali - Filmi in papir - Določanje dimenzijskih sprememb
Ta mednarodni standard določa metodo za določevanje dimenzijskih sprememb fotografskih filmov in papirja, ki jih povzročajo: spremembe v ravnotežju vsebnosti vlage zaradi spremembe relativne vlage ozračja (vlažnostni razteznostni koeficient); - sprememba temperature (koeficient toplotnega raztezanja); - procesiranje; - staranje. Ta mednarodni standard obravnava vsebnost vlage in toplotno zgodovino vzorcev pred merjenjem, pogoje ozračja med merjenjem in obdelavo podatkov. Ne opisuje različnih eksperimentalnih tehnik, ki se uporabljajo za izvedbo meritev.
General Information
Buy Standard
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 18903
First edition
2002-07-01
Imaging materials — Films and paper —
Determination of dimensional change
Matériaux pour l'image — Films et papiers — Détermination des variations
dimensionnelles
Reference number
ISO 18903:2002(E)
©
ISO 2002
---------------------- Page: 1 ----------------------
ISO 18903:2002(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 18903:2002(E)
Contents Page
Foreword.v
Introduction.vi
1 Scope .1
2 Normative reference.1
3 Terms and definitions .1
4 Measurement technique.3
5 Sampling.3
5.1 Selection of specimens.3
5.2 Handling of specimens .3
5.3 Conditioning of specimens.3
5.4 Processing of specimens .4
6 Conditioning.4
6.1 Constant humidity chamber .4
6.2 Standard temperature and humidity.4
7 Test for humidity coefficient of expansion .5
7.1 Procedure .5
7.2 Calculations .5
7.3 Test report .5
8 Test for thermal coefficient of expansion .5
8.1 General.5
8.2 Procedure .6
8.3 Calculations .6
8.4 Test report .6
9 Test for dimensional change due to processing.7
9.1 General.7
9.2 Coding system .7
9.3 Procedure .7
9.4 Calculations .8
9.5 Test report .8
10 Test for dimensional change due to processing plus ageing.8
10.1 Ageing conditions .8
10.2 Ageing time .9
10.3 Procedure .9
10.4 Calculations .9
10.5 Test report .9
© ISO 2002 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 18903:2002(E)
Annex A (informative) Numbering system for related International Standards .10
Annex B (informative) Methods of measuring dimensional change.12
Annex C (informative) Dimensional hysteresis in photographic materials.13
Bibliography .17
iv © ISO 2002 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 18903:2002(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 18903 was prepared by Technical Committee ISO/TC 42, Photography.
This first edition of ISO 18903 cancels and replaces ISO 6221:1996, which has been technically revised.
Annexes A to C of this International Standard are for information only.
© ISO 2002 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 18903:2002(E)
Introduction
Photographic films and papers exhibit temporary or reversible dimensional changes as well as permanent
dimensional changes. This International Standard is designed to provide uniform methods for treating the
specimens and for expressing the dimensional changes which occur with changes in atmospheric conditions and
those which occur in processing and ageing.
Temporary or reversible dimensional changes are the result of changes in the equilibrium moisture content (which
is determined by the relative humidity of the surrounding atmosphere) or changes in temperature. Permanent
dimensional changes occur as the result of processing and ageing. The rate of permanent shrinkage of film
generally increases with temperature, but decreases with time. The rate of shrinkage may also be greatest at either
high or low relative humidity, depending on the type of film. Some materials, particularly photographic film on
polyester base, can show a swelling after a high humidity exposure.
The increasing use of photographic films in recent years, in applications where dimensional stability is critical, has
emphasized the importance of an accurate measure of dimensional properties. For example, in photomechanical
reproductions a dimensional change of as little as 0,01 % may be of practical importance. In the case of aerial
mapping, uniform shrinkage is not serious since it can be easily corrected by a change in magnification, but any
difference in shrinkage in the two principal directions is a source of error. Any localized or non-uniform changes in
dimension are of practical concern.
The dimensional change properties of any film or paper depend not only on their composition and method of
manufacture, but also on their thermal and moisture content history. Accurate evaluation of such properties
requires some control over the specimen history as well as very precise control over the conditioning and
measuring procedures. Film and paper dimensions are also subject to hysteresis effects. These are relatively more
important with the more stable materials such as polyester photographic base films.
Additional information on the dimensional characteristics of photographic films and papers and on methods of
measurement may be found in the bibliography.
vi © ISO 2002 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 18903:2002(E)
Imaging materials — Films and paper — Determination of
dimensional change
1 Scope
This International Standard specifies a method for determining the dimensional change of photographic films and
papers caused by:
variations in equilibrium moisture content due to change in the relative humidity (RH) of the atmosphere
(humidity coefficient of expansion);
change in temperature (thermal coefficient of expansion);
processing;
ageing.
This International Standard deals with the moisture content and thermal history of the specimens before
measurement, the atmospheric conditions during measurement, and the treatment of the data. It does not describe
the various experimental techniques used to make the measurements.
This International Standard is not suitable for determining the dimensional change of instant photographic film.
2 Normative reference
The following normative document contains 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 edition of the normative document 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/TR 18931:2001, Imaging materials — Recommendations for humidity measurement and control
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
conditioning
exposure of a specimen to air at a given relative humidity and temperature until equilibrium is reached
3.2
differential dimensional change
difference between the dimensional changes of the material in the two principal directions (length and width)
NOTE Polyester-based films frequently have maximum and minimum dimensional changes in directions other than the
length or width. These can be determined by rotating and viewing the uncoated base between a pair of crossed polarizers.
© ISO 2002 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 18903:2002(E)
When the direction corresponding to either the maximum or minimum dimensional change is coincident with the optical axis of
one polarizer, there is minimum light transmission through the base.
3.3
dimensional change due to processing
permanent dimensional change caused by photographic processing
NOTE This may be the conventional wet chemical processing, vapour processing or heat processing. It is measured after
conditioning at the same relative humidity and temperature as used for the original measurement and is expressed as a
percentage.
3.4
dimensional change due to processing plus ageing
permanent dimensional change that occurs as a result of processing plus ageing of the processed material
NOTE It is measured after conditioning of the processed, aged film or paper at the same relative humidity and temperature
as used for the original measurement and is expressed as a percentage.
3.5
dimensional hysteresis
difference in the absolute dimensions of a specimen in equilibrium with air at a given relative humidity, when
conditioned from a higher relative humidity and when conditioned from a lower relative humidity
NOTE See annex C.
3.6
humidity coefficient of expansion
change in dimension per unit length per 1 % change in relative humidity at constant temperature
3.7
humidity expansion [contraction]
dimensional change caused by the gain (or loss) of moisture following changes in the relative humidity of the
ambient air at constant temperature
3.8
length direction
direction of the film or paper parallel to its forward movement in the film- or paper-making machine
NOTE This is also termed “grain” or “machine direction” in the case of papers.
3.9
preconditioning
establishment of a moisture content history by conditioning the specimen at a relative humidity above or below the
conditioning relative humidity used for measurement
NOTE The purpose of preconditioning is to control the effects of hysteresis (see 3.5).
3.10
thermal coefficient of expansion
change in dimension per unit length per 1 °C change in temperature at constant relative humidity
3.11
thermal expansion [contraction]
dimensional change caused by a rise (or fall) of temperature at constant relative humidity
NOTE This is an apparent thermal expansion, since the moisture content of film varies slightly with temperature at constant
relative humidity. However, the primary effect is thermal expansion. Thermal expansion is less important for paper because of
the small changes involved, particularly compared to humidity effects.
2 © ISO 2002 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 18903:2002(E)
3.12
width direction
direction of the film or paper at right angles to the length direction
NOTE This is also termed “cross direction”.
4 Measurement technique
There are a number of different techniques used for measuring the dimensional change of sensitized materials.
Specifications of measuring equipment are beyond the scope of this International Standard, but several
approaches are described in annex B.
5 Sampling
5.1 Selection of specimens
Specimens intended for dimensional stability tests shall exhibit no obvious physical defects, be representative of
the whole of the material being tested, be handled in the same manner as in actual use, and be treated uniformly.
When different materials are to be compared, they shall have been subjected to the same conditioning history. The
length direction should be indicated if known.
5.2 Handling of specimens
Specimens shall be prepared under controlled conditions and then separated into groups which are subjected to
different atmospheric conditions. The operator shall take care not to breathe on the specimens and shall wear
moisture-resistant gloves while handling them, since moisture from the skin may reduce the accuracy of the results.
5.3 Conditioning of specimens
5.3.1 General
Specimens shall be suspended in the conditioning atmosphere by means of a hook or a rod through a hole in the
middle of one end near the edge of the specimen. The specimens shall be separated to prevent contact with each
other. An alternative method of conditioning is to place specimens in racks spaced so that there is free circulation
of the air on both sides of the material.
Specimens shall not be removed from the conditioning atmosphere for measuring. Condition specimens until
practical moisture equilibrium has been reached. The time required to achieve this condition shall be established by
actual measurements on representative specimens or based on prior experience.
5.3.2 Film
The conditioning time for film will be about 4 h, but will vary according to access of the conditioning air, the film
type, base thickness, etc. Conditioning time shall not exceed 24 h.
At relative humidities of 60 % and above, films and papers sometimes undergo an irreversible change in size with
time. For this reason, the conditioning time shall be standardized for comparison purposes.
5.3.3 Paper
Double-weight fibre-base papers will require about 1 d of conditioning; resin-coated papers require at least 7 d.
© ISO 2002 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO 18903:2002(E)
5.4 Processing of specimens
Specimens shall be exposed and processed by methods and equipment normal for the product. When the effects
of processing machines, tensions or drying conditions are being investigated, the film or paper shall be processed
in the sizes of practical interest.
Specimens may be developed as negatives or as positives, but this can affect the dimensional change properties
of some materials. Silver-gelatin films generally show less dimensional change when they have low density rather
than high density.
6 Conditioning
6.1 Constant humidity chamber
6.1.1 General
Either a walk-in constant humidity room or a cabinet may be used.
6.1.2 Constant humidity room
The relative humidity (RH) shall be held constant to ± 1 % or better in areas of the room where specimens are
measured. The room shall be vapour sealed, insulated on all six sides, and shall be mechanically air-conditioned.
Air shall be circulated at a linear velocity of at least 15 cm/s. The number of personnel permitted in the room at any
one time during testing shall be limited.
The relative humidity of the room shall be checked regularly, preferably by means of an electric hygrometer
calibrated by a dew-point method.
Humidity measurements to within ± 1 % RH are difficult and are to be carried out in accordance with
ISO/TR 18931.
6.1.3 Constant humidity cabinet
A convenient size for a humidity cabinet is approximately 1 m in height and 0,5 m in width and depth. It shall be
constructed of materials that will ensure good insulation. Suitable provision shall be made for thermostatically
controlling the temperature within the cabinet. Air shall be circulated throughout the cabinet at a linear velocity of at
least 30 cm/s.
The cabinet shall be equipped with ports filled with moisture-impermeable (e.g. rubber or plastic) gloves for
entrance of the operator’s hands. The relative humidity of the cabinet shall be checked regularly, preferably by
means of an electric hygrometer calibrated by a dew-point method.
The relative humidity within the cabinet shall be controlled as closely as possible. Where the cabinet is
mechanically air-conditioned, the relative humidity shall be maintained to ± 1 % or better. Where a saturated salt
solution is used for control, provision shall be made at the bottom of the cabinet for inserting suitable trays, which
2
shall hold about 1 l of salt solution. A solution tray with a large surface area is needed and about 100 cm is
suitable.
6.2 Standard temperature and humidity
The standard temperature shall be 23 °C ± 0,5 °C except for the test specified in clause 8. The relative humidity is
specified in the respective test procedure and depends upon the property being measured.
4 © ISO 2002 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 18903:2002(E)
7 Test for humidity coefficient of expansion
7.1 Procedure
Five specimens shall be preconditioned at 10 % RH to 15 % RH, then conditioned at 15 % RH to 25 % RH (but at
least 5 % RH above the preconditioning relative humidity) and measured. Preconditioning times of 1 h to 2 h are
recommended for photographic film, 4 h for fibre-base paper and 7 d for resin-coated paper. The specimens shall
then be conditioned again at 50 % RH to 60 % RH and remeasured. This range of relative humidity is selected
because the dimensions with respect to the relative humidity curve for some materials is abnormal, i.e. above
60 % RH (see annex C). The conditioning temperature shall be maintained as specified in 6.2. The two
conditioning humidities shall be measured to an accuracy of ± 1 % RH in accordance with 6.1.2.
The test may be made on both unprocessed and processed specimens depending on the measuring method used
(see annex B). The humidity coefficients of expansion of unprocessed and processed film are generally not the
same.
7.2 Calculations
Since the dimensional change curve versus relative humidity is not always linear (see annex C), this test method
gives only an average coefficient over the range measured. The dimensional change between the two
measurements of five specimens shall be averaged and the humidity coefficients of expansion shall be calculated
in accordance with the following equation:
ll−
21
H =
l ×DRH
1
where
H is the humidity coefficient of expansion;
l is the gauge distance or the dimension measured at the initial conditioning temperature and relative
1
humidity;
l is the gauge distance or the dimension measured at the final conditioning temperature and relative
2
humidity;
∆RH is the difference between the two conditioning relative humidities used, as a percentage.
7.3 Test report
The test report shall contain the following:
humidity coefficients of expansion for both the length and width directions;
two conditioning relative humidities and temperature;
a statement as to whether the specimens were unprocessed, processed to high density, or processed clear.
8 Test for thermal coefficient of expansion
8.1 General
This method is of importance for photographic film.
© ISO 2002 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO 18903:2002(E)
NOTE Dimensional changes of photographic paper with reasonable changes in temperature (but at the same moisture
content) are so small that measurement is very difficult and has little practical significance.
8.2 Procedure
Five specimens shall be conditioned, first at 45 °C to 50 °C and measured, and then conditioned at 10 °C to 25 °C
and measured again. A conditioning time of 4 h at each temperature is recommended.
NOTE 1 The high-temperature measurement is made first so that any permanent shrinkage which may occur during
conditioning will not affect the result.
Both the specimens and the measuring equipment shall be at thermal equilibrium. The relative humidity shall be
the same at both temperatures and controlled as specified in 6.1. A low humidity is more practical for laboratory
work, but other relative humidities may be used.
NOTE 2 The thermal coefficient of expansion varies slightly with relative humidity for some materials.
The test can be made on either unprocessed or processed material, depending on the measuring method used
(see annex B). The measuring equipment shall not be affected by the thermal changes or else the measurements
shall be corrected for thermal effects.
8.3 Calculations
The dimensional change between the two measurements of five specimens shall be averaged and the thermal
coefficients of expansion shall be calculated in accordance with the following equation:
ll−
43
α =
lT×D
3
where
α is the thermal coefficient of expansion;
l is the gauge distance or the dimension measured at the initial conditioning temperature and relative
3
humidity;
l is the gauge distance or the dimension measured at the final conditioning temperature and relative
4
humidity;
∆T is the difference between the two conditioning temperatures used, in degrees Celsius.
Depending on the type and composition of the measuring equipment, it may be necessary to correct for the thermal
expansion of the gauge or of the reference standard.
8.4 Test report
The test report shall contain the following:
thermal coefficients of expansion for both the length and width directions;
conditioning temperatures and relative humidity;
a statement as to whether the specimens were unprocessed, processed to high density, or processed clear.
6 © ISO 2002 – All rights reserved
---------------------- Page: 12 ----------------------
ISO 18903:2002(E)
9 Test for dimensional change due to processing
9.1 Relative humidity
9.1.1 General
The dimensional change due to processing of photographic films and papers can be markedly affected by the
following three variables in the test procedure.
9.1.2 Relative humidity for preconditioning of a raw specimen
The dimensions of the unprocessed specimen at a given relative humidity can be dependent to a large extent upon
the earlier humidity used for preconditioning (preconditioning humidity history). This is due to the hysteresis and
relaxation effects described in annex C.
It is necessary to specify whether the specimen had been preconditioned from a lower humidity or from a higher
humidity prior to the original measurement on the unprocessed material. This is indicated by the letter “L” for the
former and “H” for the latter. When a specimen is measured from the original box (or packaging) without
preconditioning, the letter “B” is used.
9.1.3 Relative humidity for preconditioning of a processed specimen
The preconditioning humidity history is as important for the dimensions of the processed specimen as for the raw
specimen described in 9.1.2. The letters “L” and “H” are also used to indicate the humidity history of the processed
material. The letter “H” is also used when the specimen is dried after processing at the measuring humidity.
Although the drying conditions after processing affect the dimensional change due to processing, the effect is
eliminated when the processed specimen is preconditioned. If measurements are made on a processed specimen
that is not preconditioned after processing, the letter “M” is used.
9.1.4 Relative humidity condition
Specimens shall be conditioned to moisture equilibrium using the same relative humidity for both the raw and
processed measurements. Otherwise, a reversible humidity change will be included in the measured dimensional
change. However, the dimensional change due to processing can be very dependent upon the relative humidity at
which those measurements are made and this shall be indicated when reporting the results.
9.2 Coding system
A wide variety of test procedures can be used for the measurement of dimensional change due to processing by
varying the preconditioning history of the raw and processed specimens and
...
SLOVENSKI STANDARD
SIST ISO 18903:2011
01-julij-2011
8SRGRELWYHQLPDWHULDOL)LOPLLQSDSLU'RORþDQMHGLPHQ]LMVNLKVSUHPHPE
Imaging materials - Films and paper - Determination of dimensional change
Matériaux pour l'image - Films et papiers - Détermination des variations dimensionnelles
Ta slovenski standard je istoveten z: ISO 18903:2002
ICS:
37.040.20 )RWRJUDIVNLSDSLUILOPLLQ Photographic paper, films
IRWRJUDIVNHSORãþH)LOPVNL and cartridges
]YLWNL
SIST ISO 18903:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 18903:2011
---------------------- Page: 2 ----------------------
SIST ISO 18903:2011
INTERNATIONAL ISO
STANDARD 18903
First edition
2002-07-01
Imaging materials — Films and paper —
Determination of dimensional change
Matériaux pour l'image — Films et papiers — Détermination des variations
dimensionnelles
Reference number
ISO 18903:2002(E)
©
ISO 2002
---------------------- Page: 3 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(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 18903:2011
ISO 18903:2002(E)
Contents Page
Foreword.v
Introduction.vi
1 Scope .1
2 Normative reference.1
3 Terms and definitions .1
4 Measurement technique.3
5 Sampling.3
5.1 Selection of specimens.3
5.2 Handling of specimens .3
5.3 Conditioning of specimens.3
5.4 Processing of specimens .4
6 Conditioning.4
6.1 Constant humidity chamber .4
6.2 Standard temperature and humidity.4
7 Test for humidity coefficient of expansion .5
7.1 Procedure .5
7.2 Calculations .5
7.3 Test report .5
8 Test for thermal coefficient of expansion .5
8.1 General.5
8.2 Procedure .6
8.3 Calculations .6
8.4 Test report .6
9 Test for dimensional change due to processing.7
9.1 General.7
9.2 Coding system .7
9.3 Procedure .7
9.4 Calculations .8
9.5 Test report .8
10 Test for dimensional change due to processing plus ageing.8
10.1 Ageing conditions .8
10.2 Ageing time .9
10.3 Procedure .9
10.4 Calculations .9
10.5 Test report .9
© ISO 2002 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(E)
Annex A (informative) Numbering system for related International Standards .10
Annex B (informative) Methods of measuring dimensional change.12
Annex C (informative) Dimensional hysteresis in photographic materials.13
Bibliography .17
iv © ISO 2002 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(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 18903 was prepared by Technical Committee ISO/TC 42, Photography.
This first edition of ISO 18903 cancels and replaces ISO 6221:1996, which has been technically revised.
Annexes A to C of this International Standard are for information only.
© ISO 2002 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(E)
Introduction
Photographic films and papers exhibit temporary or reversible dimensional changes as well as permanent
dimensional changes. This International Standard is designed to provide uniform methods for treating the
specimens and for expressing the dimensional changes which occur with changes in atmospheric conditions and
those which occur in processing and ageing.
Temporary or reversible dimensional changes are the result of changes in the equilibrium moisture content (which
is determined by the relative humidity of the surrounding atmosphere) or changes in temperature. Permanent
dimensional changes occur as the result of processing and ageing. The rate of permanent shrinkage of film
generally increases with temperature, but decreases with time. The rate of shrinkage may also be greatest at either
high or low relative humidity, depending on the type of film. Some materials, particularly photographic film on
polyester base, can show a swelling after a high humidity exposure.
The increasing use of photographic films in recent years, in applications where dimensional stability is critical, has
emphasized the importance of an accurate measure of dimensional properties. For example, in photomechanical
reproductions a dimensional change of as little as 0,01 % may be of practical importance. In the case of aerial
mapping, uniform shrinkage is not serious since it can be easily corrected by a change in magnification, but any
difference in shrinkage in the two principal directions is a source of error. Any localized or non-uniform changes in
dimension are of practical concern.
The dimensional change properties of any film or paper depend not only on their composition and method of
manufacture, but also on their thermal and moisture content history. Accurate evaluation of such properties
requires some control over the specimen history as well as very precise control over the conditioning and
measuring procedures. Film and paper dimensions are also subject to hysteresis effects. These are relatively more
important with the more stable materials such as polyester photographic base films.
Additional information on the dimensional characteristics of photographic films and papers and on methods of
measurement may be found in the bibliography.
vi © ISO 2002 – All rights reserved
---------------------- Page: 8 ----------------------
SIST ISO 18903:2011
INTERNATIONAL STANDARD ISO 18903:2002(E)
Imaging materials — Films and paper — Determination of
dimensional change
1 Scope
This International Standard specifies a method for determining the dimensional change of photographic films and
papers caused by:
variations in equilibrium moisture content due to change in the relative humidity (RH) of the atmosphere
(humidity coefficient of expansion);
change in temperature (thermal coefficient of expansion);
processing;
ageing.
This International Standard deals with the moisture content and thermal history of the specimens before
measurement, the atmospheric conditions during measurement, and the treatment of the data. It does not describe
the various experimental techniques used to make the measurements.
This International Standard is not suitable for determining the dimensional change of instant photographic film.
2 Normative reference
The following normative document contains 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 edition of the normative document 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/TR 18931:2001, Imaging materials — Recommendations for humidity measurement and control
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
conditioning
exposure of a specimen to air at a given relative humidity and temperature until equilibrium is reached
3.2
differential dimensional change
difference between the dimensional changes of the material in the two principal directions (length and width)
NOTE Polyester-based films frequently have maximum and minimum dimensional changes in directions other than the
length or width. These can be determined by rotating and viewing the uncoated base between a pair of crossed polarizers.
© ISO 2002 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(E)
When the direction corresponding to either the maximum or minimum dimensional change is coincident with the optical axis of
one polarizer, there is minimum light transmission through the base.
3.3
dimensional change due to processing
permanent dimensional change caused by photographic processing
NOTE This may be the conventional wet chemical processing, vapour processing or heat processing. It is measured after
conditioning at the same relative humidity and temperature as used for the original measurement and is expressed as a
percentage.
3.4
dimensional change due to processing plus ageing
permanent dimensional change that occurs as a result of processing plus ageing of the processed material
NOTE It is measured after conditioning of the processed, aged film or paper at the same relative humidity and temperature
as used for the original measurement and is expressed as a percentage.
3.5
dimensional hysteresis
difference in the absolute dimensions of a specimen in equilibrium with air at a given relative humidity, when
conditioned from a higher relative humidity and when conditioned from a lower relative humidity
NOTE See annex C.
3.6
humidity coefficient of expansion
change in dimension per unit length per 1 % change in relative humidity at constant temperature
3.7
humidity expansion [contraction]
dimensional change caused by the gain (or loss) of moisture following changes in the relative humidity of the
ambient air at constant temperature
3.8
length direction
direction of the film or paper parallel to its forward movement in the film- or paper-making machine
NOTE This is also termed “grain” or “machine direction” in the case of papers.
3.9
preconditioning
establishment of a moisture content history by conditioning the specimen at a relative humidity above or below the
conditioning relative humidity used for measurement
NOTE The purpose of preconditioning is to control the effects of hysteresis (see 3.5).
3.10
thermal coefficient of expansion
change in dimension per unit length per 1 °C change in temperature at constant relative humidity
3.11
thermal expansion [contraction]
dimensional change caused by a rise (or fall) of temperature at constant relative humidity
NOTE This is an apparent thermal expansion, since the moisture content of film varies slightly with temperature at constant
relative humidity. However, the primary effect is thermal expansion. Thermal expansion is less important for paper because of
the small changes involved, particularly compared to humidity effects.
2 © ISO 2002 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(E)
3.12
width direction
direction of the film or paper at right angles to the length direction
NOTE This is also termed “cross direction”.
4 Measurement technique
There are a number of different techniques used for measuring the dimensional change of sensitized materials.
Specifications of measuring equipment are beyond the scope of this International Standard, but several
approaches are described in annex B.
5 Sampling
5.1 Selection of specimens
Specimens intended for dimensional stability tests shall exhibit no obvious physical defects, be representative of
the whole of the material being tested, be handled in the same manner as in actual use, and be treated uniformly.
When different materials are to be compared, they shall have been subjected to the same conditioning history. The
length direction should be indicated if known.
5.2 Handling of specimens
Specimens shall be prepared under controlled conditions and then separated into groups which are subjected to
different atmospheric conditions. The operator shall take care not to breathe on the specimens and shall wear
moisture-resistant gloves while handling them, since moisture from the skin may reduce the accuracy of the results.
5.3 Conditioning of specimens
5.3.1 General
Specimens shall be suspended in the conditioning atmosphere by means of a hook or a rod through a hole in the
middle of one end near the edge of the specimen. The specimens shall be separated to prevent contact with each
other. An alternative method of conditioning is to place specimens in racks spaced so that there is free circulation
of the air on both sides of the material.
Specimens shall not be removed from the conditioning atmosphere for measuring. Condition specimens until
practical moisture equilibrium has been reached. The time required to achieve this condition shall be established by
actual measurements on representative specimens or based on prior experience.
5.3.2 Film
The conditioning time for film will be about 4 h, but will vary according to access of the conditioning air, the film
type, base thickness, etc. Conditioning time shall not exceed 24 h.
At relative humidities of 60 % and above, films and papers sometimes undergo an irreversible change in size with
time. For this reason, the conditioning time shall be standardized for comparison purposes.
5.3.3 Paper
Double-weight fibre-base papers will require about 1 d of conditioning; resin-coated papers require at least 7 d.
© ISO 2002 – All rights reserved 3
---------------------- Page: 11 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(E)
5.4 Processing of specimens
Specimens shall be exposed and processed by methods and equipment normal for the product. When the effects
of processing machines, tensions or drying conditions are being investigated, the film or paper shall be processed
in the sizes of practical interest.
Specimens may be developed as negatives or as positives, but this can affect the dimensional change properties
of some materials. Silver-gelatin films generally show less dimensional change when they have low density rather
than high density.
6 Conditioning
6.1 Constant humidity chamber
6.1.1 General
Either a walk-in constant humidity room or a cabinet may be used.
6.1.2 Constant humidity room
The relative humidity (RH) shall be held constant to ± 1 % or better in areas of the room where specimens are
measured. The room shall be vapour sealed, insulated on all six sides, and shall be mechanically air-conditioned.
Air shall be circulated at a linear velocity of at least 15 cm/s. The number of personnel permitted in the room at any
one time during testing shall be limited.
The relative humidity of the room shall be checked regularly, preferably by means of an electric hygrometer
calibrated by a dew-point method.
Humidity measurements to within ± 1 % RH are difficult and are to be carried out in accordance with
ISO/TR 18931.
6.1.3 Constant humidity cabinet
A convenient size for a humidity cabinet is approximately 1 m in height and 0,5 m in width and depth. It shall be
constructed of materials that will ensure good insulation. Suitable provision shall be made for thermostatically
controlling the temperature within the cabinet. Air shall be circulated throughout the cabinet at a linear velocity of at
least 30 cm/s.
The cabinet shall be equipped with ports filled with moisture-impermeable (e.g. rubber or plastic) gloves for
entrance of the operator’s hands. The relative humidity of the cabinet shall be checked regularly, preferably by
means of an electric hygrometer calibrated by a dew-point method.
The relative humidity within the cabinet shall be controlled as closely as possible. Where the cabinet is
mechanically air-conditioned, the relative humidity shall be maintained to ± 1 % or better. Where a saturated salt
solution is used for control, provision shall be made at the bottom of the cabinet for inserting suitable trays, which
2
shall hold about 1 l of salt solution. A solution tray with a large surface area is needed and about 100 cm is
suitable.
6.2 Standard temperature and humidity
The standard temperature shall be 23 °C ± 0,5 °C except for the test specified in clause 8. The relative humidity is
specified in the respective test procedure and depends upon the property being measured.
4 © ISO 2002 – All rights reserved
---------------------- Page: 12 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(E)
7 Test for humidity coefficient of expansion
7.1 Procedure
Five specimens shall be preconditioned at 10 % RH to 15 % RH, then conditioned at 15 % RH to 25 % RH (but at
least 5 % RH above the preconditioning relative humidity) and measured. Preconditioning times of 1 h to 2 h are
recommended for photographic film, 4 h for fibre-base paper and 7 d for resin-coated paper. The specimens shall
then be conditioned again at 50 % RH to 60 % RH and remeasured. This range of relative humidity is selected
because the dimensions with respect to the relative humidity curve for some materials is abnormal, i.e. above
60 % RH (see annex C). The conditioning temperature shall be maintained as specified in 6.2. The two
conditioning humidities shall be measured to an accuracy of ± 1 % RH in accordance with 6.1.2.
The test may be made on both unprocessed and processed specimens depending on the measuring method used
(see annex B). The humidity coefficients of expansion of unprocessed and processed film are generally not the
same.
7.2 Calculations
Since the dimensional change curve versus relative humidity is not always linear (see annex C), this test method
gives only an average coefficient over the range measured. The dimensional change between the two
measurements of five specimens shall be averaged and the humidity coefficients of expansion shall be calculated
in accordance with the following equation:
ll−
21
H =
l ×DRH
1
where
H is the humidity coefficient of expansion;
l is the gauge distance or the dimension measured at the initial conditioning temperature and relative
1
humidity;
l is the gauge distance or the dimension measured at the final conditioning temperature and relative
2
humidity;
∆RH is the difference between the two conditioning relative humidities used, as a percentage.
7.3 Test report
The test report shall contain the following:
humidity coefficients of expansion for both the length and width directions;
two conditioning relative humidities and temperature;
a statement as to whether the specimens were unprocessed, processed to high density, or processed clear.
8 Test for thermal coefficient of expansion
8.1 General
This method is of importance for photographic film.
© ISO 2002 – All rights reserved 5
---------------------- Page: 13 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(E)
NOTE Dimensional changes of photographic paper with reasonable changes in temperature (but at the same moisture
content) are so small that measurement is very difficult and has little practical significance.
8.2 Procedure
Five specimens shall be conditioned, first at 45 °C to 50 °C and measured, and then conditioned at 10 °C to 25 °C
and measured again. A conditioning time of 4 h at each temperature is recommended.
NOTE 1 The high-temperature measurement is made first so that any permanent shrinkage which may occur during
conditioning will not affect the result.
Both the specimens and the measuring equipment shall be at thermal equilibrium. The relative humidity shall be
the same at both temperatures and controlled as specified in 6.1. A low humidity is more practical for laboratory
work, but other relative humidities may be used.
NOTE 2 The thermal coefficient of expansion varies slightly with relative humidity for some materials.
The test can be made on either unprocessed or processed material, depending on the measuring method used
(see annex B). The measuring equipment shall not be affected by the thermal changes or else the measurements
shall be corrected for thermal effects.
8.3 Calculations
The dimensional change between the two measurements of five specimens shall be averaged and the thermal
coefficients of expansion shall be calculated in accordance with the following equation:
ll−
43
α =
lT×D
3
where
α is the thermal coefficient of expansion;
l is the gauge distance or the dimension measured at the initial conditioning temperature and relative
3
humidity;
l is the gauge distance or the dimension measured at the final conditioning temperature and relative
4
humidity;
∆T is the difference between the two conditioning temperatures used, in degrees Celsius.
Depending on the type and composition of the measuring equipment, it may be necessary to correct for the thermal
expansion of the gauge or of the reference standard.
8.4 Test report
The test report shall contain the following:
thermal coefficients of expansion for both the length and width directions;
conditioning temperatures and relative humidity;
a statement as to whether the specimens were unprocessed, processed to high density, or processed clear.
6 © ISO 2002 – All rights reserved
---------------------- Page: 14 ----------------------
SIST ISO 18903:2011
ISO 18903:2002(E)
9 Test for dimensional change due to processing
9.1 Relative humidity
9.1.1 General
The dimensional change due to processing of photographic films and papers can be markedly affected by the
following three variables in the test procedure.
9.1.2 Relative humidity for preconditioning of a raw specimen
The dimensions of the unprocessed specimen at a given relative humidity can be dependent to a large extent upon
the earlier humidity used for preconditioning (preconditioning humidity history). This is due to the hysteresis and
relaxation effects described in annex C.
It is necessary to specify whether the specimen had been preconditioned from a lower humidity or from a higher
humidity prior to the original measurement on the unprocessed material. This is indicated by the letter “L” for the
former and “H” for the latter. When a specimen is measured from the original box (or packaging) without
preconditioning, the letter “B” is used.
9.1.3 Relative humidity for preconditioning of a processed specimen
The preconditioning humidity history is as important for the dimensions of the processed specimen as for the raw
specimen described in 9.1.2. The letters “L” and “H” are also used to indicate the humidity history of the processed
material. The letter “H” is also used w
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.