ISO 9416:2017
(Main)Paper — Determination of light scattering and absorption coefficients (using Kubelka-Munk theory)
Paper — Determination of light scattering and absorption coefficients (using Kubelka-Munk theory)
ISO 9416:2017 specifies a method for the calculation of light-scattering and light-absorption coefficients based upon diffuse reflectance measurements made under the conditions specified in ISO 2469 using the colour matching function ȳ(λ) and CIE illuminant C. It is emphasized that the strict evaluation of the light-scattering and light-absorption coefficients requires conditions which cannot be achieved with the instrumentation specified here. The values obtained by application of this document are dependent on the application of the Kubelka-Munk equations, not to full reflectance data but to reflectance factor data obtained using the specified d/0° geometry and a gloss trap. The use of the method is restricted to white and near-white uncoated papers with an opacity less than about 95 %. Paper that has been treated with a fluorescent dyestuff or that exhibits significant fluorescence can only be dealt with if a filter with a cut-off wavelength of 420 nm is used to eliminate all the fluorescence effect in the UVex(420) mode.
Papier — Détermination des coefficients de diffusion et d'absorption de la lumière (utilisation de la théorie de Kubelka-Munk)
Papir - Določanje koeficienta sipanja in koeficienta absorpcije svetlobe (uporaba teorije po Kubelka-Munku)
Ta dokument določa metodo za izračun koeficienta sipanja svetlobe in koeficienta absorpcije svetlobe na podlagi meritev razpršene odsevnosti pod pogoji, ki so določeni v standardu ISO 2469, z uporabo barvne funkcije ȳ(λ) in svetila C po standardu CIE.
Poudariti je treba, da so za strogo oceno koeficientov sipanja svetlobe in absorpcije svetlobe nujni pogoji, ki jih ni mogoče doseči z instrumenti, opredeljenimi v tem dokumentu. Vrednosti, pridobljene z uporabo tega dokumenta, so odvisne od uporabe enačb Kubelka-Munk, ne za polne podatke o odsevnosti, ampak za podatke o faktorju refleksije, ki so pridobljeni z uporabo določene geometrije d/0° in z zadrževanjem sijaja.
Uporaba te metode je omejena na bele in skoraj bele neprevlečene papirje z motnostjo, manjšo od približno 95 %. Papir, ki je bil obdelan s fluorescenčnimi barvili ali ki kaže bistveno fluorescenco, je mogoče obravnavati samo, če se uporabi filter z mejno valovno dolžino 420 nm, ki v celoti odstrani fluorescenčni učinek v načinu UVex(420).
OPOMBA 1: Preostalo UV-sevanje v instrumentu je lahko odvisno od tega, ali je instrument prilagojen na pogoje UV(C) ali UV(D65), preden je preklopljen v način UVex(420), vendar velja, da je mogoče to negotovost glede preostalega sevanja prezreti pri uporabi tega dokumenta.
OPOMBA 2: Čeprav je ta metoda omejena na papir, jo je mogoče uporabiti za liste iz pulpe, čeprav to ni v skladu s tem dokumentom. Na splošno sta pri preskušanju pulp veliko bolj kot ovrednotena vrednost, standardizirana v tem dokumentu, zanimiva koeficient absorpcije svetlobe pri 457 nm, ki ustreza vrednostjo svetlosti ISO, ali koeficient spektralne absorpcije.
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INTERNATIONAL ISO
STANDARD 9416
Third edition
2017-05
Paper — Determination of light
scattering and absorption coefficients
(using Kubelka-Munk theory)
Papier — Détermination des coefficients de diffusion et d’absorption
de la lumière (utilisation de la théorie de Kubelka-Munk)
Reference number
ISO 9416:2017(E)
©
ISO 2017
---------------------- Page: 1 ----------------------
ISO 9416:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 9416:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus . 3
6 Sampling and conditioning . 4
7 Preparation of test pieces . 4
8 Procedure. 4
9 Calculation of results . 5
10 Test report . 5
Annex A (informative) Spectral characteristics of reflectometers for measuring luminance factor 6
Annex B (informative) Precision .10
Bibliography .11
© ISO 2017 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 9416:2017(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps.
This third edition cancels and replaces the second edition (ISO 9416:2009), which has been technically
revised, to allow for calculations to use ASTM E308 for instruments that have bandpass correction and
still maintain the procedure for instruments without bandpass correction.
iv © ISO 2017 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 9416:2017(E)
Introduction
The opacity of a paper is dependent on its grammage, but it is also intrinsically dependent on the light-
absorption and light-scattering coefficients of the material. These coefficients are calculated from the
values of the reflectance factor over a black backing, the intrinsic reflectance factor and the grammage
of the sheet.
The calculation of these coefficients requires luminance factor data obtained by measurement under
specified conditions. Apart from the optical properties of the sample, the luminance factor depends on
the conditions of measurement and particularly on the spectral and geometric characteristics of the
instrument used for its determination. This document is therefore intended to be read in conjunction
with ISO 2469 and ISO 2471.
NOTE This method is based on a theory developed by Kubelka and Munk. This theory describes scattering
and absorption processes with certain approximations and simplifications and can therefore yield questionable
results in extreme cases. However, the Kubelka-Munk theory offers a simple method for determining these
coefficients with the instrument used for the determination of optical properties of paper and pulps. Moreover,
the method based on this theory has been successfully used in practical applications.
© ISO 2017 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 9416:2017(E)
Paper — Determination of light scattering and absorption
coefficients (using Kubelka-Munk theory)
1 Scope
This document specifies a method for the calculation of light-scattering and light-absorption coefficients
based upon diffuse reflectance measurements made under the conditions specified in ISO 2469 using
the colour matching function ȳ(λ) and CIE illuminant C.
It is emphasized that the strict evaluation of the light-scattering and light-absorption coefficients
requires conditions which cannot be achieved with the instrumentation specified here. The values
obtained by application of this document are dependent on the application of the Kubelka-Munk
equations, not to full reflectance data but to reflectance factor data obtained using the specified d/0°
geometry and a gloss trap.
The use of the method is restricted to white and near-white uncoated papers with an opacity less
than about 95 %. Paper that has been treated with a fluorescent dyestuff or that exhibits significant
fluorescence can only be dealt with if a filter with a cut-off wavelength of 420 nm is used to eliminate all
the fluorescence effect in the UVex(420) mode.
NOTE 1 The residual UV-level in the instrument may depend on whether the instrument is adjusted to UV(C)
or UV(D65) conditions prior to switching to the UVex(420) mode, but it is considered that this uncertainty in the
residual level can be ignored in the application of this document.
NOTE 2 Although this method is restricted to paper, it can be applied to pulp sheets, although this is not in
accordance with this document. In general, when pulps are tested, the light-absorption coefficient at 457 nm
corresponding to the ISO brightness value or the spectral absorption coefficients are of greater interest than the
weighted value standardized in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 186, Paper and board — Sampling to determine average quality
ISO 187, Paper, board and pulps — Standard atmosphere for conditioning and testing and procedure for
monitoring the atmosphere and conditioning of samples
ISO 536, Paper and board — Determination of grammage
ISO 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
© ISO 2017 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 9416:2017(E)
3.1
reflectance factor
R
ratio of the radiation reflected by a surface element of a body, in the direction delimited by a given cone
with its apex at the surface element, to that reflected by the perfect reflecting diffuser under the same
conditions of irradiation
Note 1 to entry: The ratio is often expressed as a percentage.
3.2
luminance factor (C)
R
y
reflectance factor (3.1) defined with reference to the visual efficiency function V()λ and the CIE
illuminant C
Note 1 to entry: The visual efficiency function describes the sensitivity of the eye to light, so that the luminance
factor corresponds to the attribute of visual perception of the reflecting surface.
Note 2 to entry: For computational purposes, the V()λ function is identical to the CIE 1931 colour matching
function y()λ .
3.3
single-sheet luminance factor (C)
R
y,0
luminance factor (C) (3.2) of a single sheet of paper with a black cavity as backing
3.4
intrinsic luminance factor (C)
R
y,∞
luminance factor (C) (3.2) of a layer or pad of material thick enough to be opaque, i.e. such that increasing
the thickness of the pad by doubling the number of sheets results in no change in the measured
reflectance factor
[SOURCE: ISO 2471:2008, 3.4]
3.5
opacity (paper backing)
ratio of the single-sheet luminance factor (C), R , (3.3) to the intrinsic luminance factor (C), R , (3.4) of
y,0 y,∞
the same sample
Note 1 to entry: The opacity is expressed as a percentage.
3.6
light-absorption coefficient
k
fraction of the spectral radiant flux diffusely incident on a differential layer within a material that is
absorbed when the flux passes through the layer, divided by the thickness of the layer
Note 1 to entry: The flux referred to is a radiant flux across the differential layer.
3.7
light-scattering coefficient
s
fraction of the spectral radiant flux diffusely incident on a differential layer within a material that is
reflected when the flux passes through the layer, divided by the thickness of the layer
Note 1 to entry: The flux referred to is a radiant flux across the differential layer.
Note 2 to entry: It is assumed that no reflection occurs at the boundaries of the material.
2 © ISO 2017 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 9416:2017(E)
Note 3 to entry: In a two-flux system, the scattering coefficient is equal to the net transfer of flux from the
stronger flux to the weaker flux in a differential layer within a material divided by the product of the thickness of
the layer and the difference between the fluxes (see ISO 186).
3.8
light-scattering coefficient by reflectance factor measurements
s
y
coefficient calculated by application of the Kubelka-Munk equations to
luminance factor data weighted with respect to the CIE illuminant C, obtained in an instrument having
a specified geometry and calibrated in a specified manner, on the basis of grammage
2
Note 1 to entry: s is expressed in square metres per kilogram (m /kg).
y
3.9
light-absorption coefficient by reflectance factor measurements
k
y
coefficient calculated by application of the Kubelka-Munk equations to
luminance factor data weighted with respect to the CIE illuminant C, obtained in an instrument having
a specified geometry and calibrated in a specified
...
SLOVENSKI STANDARD
oSIST ISO 9416:2018
01-julij-2018
3DSLU'RORþDQMHNRHILFLHQWDVLSDQMDLQNRHILFLHQWDDEVRUSFLMHVYHWOREH XSRUDED
WHRULMHSR.XEHOND0XQNX
Paper -- Determination of light scattering and absorption coefficients (using Kubelka-
Munk theory)
Papier -- Détermination des coefficients de diffusion et d'absorption de la lumière
(utilisation de la théorie de Kubelka-Munk)
Ta slovenski standard je istoveten z: ISO 9416:2017
ICS:
85.060 Papir, karton in lepenka Paper and board
oSIST ISO 9416:2018 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST ISO 9416:2018
---------------------- Page: 2 ----------------------
oSIST ISO 9416:2018
INTERNATIONAL ISO
STANDARD 9416
Third edition
2017-05
Paper — Determination of light
scattering and absorption coefficients
(using Kubelka-Munk theory)
Papier — Détermination des coefficients de diffusion et d’absorption
de la lumière (utilisation de la théorie de Kubelka-Munk)
Reference number
ISO 9416:2017(E)
©
ISO 2017
---------------------- Page: 3 ----------------------
oSIST ISO 9416:2018
ISO 9416:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST ISO 9416:2018
ISO 9416:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus . 3
6 Sampling and conditioning . 4
7 Preparation of test pieces . 4
8 Procedure. 4
9 Calculation of results . 5
10 Test report . 5
Annex A (informative) Spectral characteristics of reflectometers for measuring luminance factor 6
Annex B (informative) Precision .10
Bibliography .11
© ISO 2017 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST ISO 9416:2018
ISO 9416:2017(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps.
This third edition cancels and replaces the second edition (ISO 9416:2009), which has been technically
revised, to allow for calculations to use ASTM E308 for instruments that have bandpass correction and
still maintain the procedure for instruments without bandpass correction.
iv © ISO 2017 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST ISO 9416:2018
ISO 9416:2017(E)
Introduction
The opacity of a paper is dependent on its grammage, but it is also intrinsically dependent on the light-
absorption and light-scattering coefficients of the material. These coefficients are calculated from the
values of the reflectance factor over a black backing, the intrinsic reflectance factor and the grammage
of the sheet.
The calculation of these coefficients requires luminance factor data obtained by measurement under
specified conditions. Apart from the optical properties of the sample, the luminance factor depends on
the conditions of measurement and particularly on the spectral and geometric characteristics of the
instrument used for its determination. This document is therefore intended to be read in conjunction
with ISO 2469 and ISO 2471.
NOTE This method is based on a theory developed by Kubelka and Munk. This theory describes scattering
and absorption processes with certain approximations and simplifications and can therefore yield questionable
results in extreme cases. However, the Kubelka-Munk theory offers a simple method for determining these
coefficients with the instrument used for the determination of optical properties of paper and pulps. Moreover,
the method based on this theory has been successfully used in practical applications.
© ISO 2017 – All rights reserved v
---------------------- Page: 7 ----------------------
oSIST ISO 9416:2018
---------------------- Page: 8 ----------------------
oSIST ISO 9416:2018
INTERNATIONAL STANDARD ISO 9416:2017(E)
Paper — Determination of light scattering and absorption
coefficients (using Kubelka-Munk theory)
1 Scope
This document specifies a method for the calculation of light-scattering and light-absorption coefficients
based upon diffuse reflectance measurements made under the conditions specified in ISO 2469 using
the colour matching function ȳ(λ) and CIE illuminant C.
It is emphasized that the strict evaluation of the light-scattering and light-absorption coefficients
requires conditions which cannot be achieved with the instrumentation specified here. The values
obtained by application of this document are dependent on the application of the Kubelka-Munk
equations, not to full reflectance data but to reflectance factor data obtained using the specified d/0°
geometry and a gloss trap.
The use of the method is restricted to white and near-white uncoated papers with an opacity less
than about 95 %. Paper that has been treated with a fluorescent dyestuff or that exhibits significant
fluorescence can only be dealt with if a filter with a cut-off wavelength of 420 nm is used to eliminate all
the fluorescence effect in the UVex(420) mode.
NOTE 1 The residual UV-level in the instrument may depend on whether the instrument is adjusted to UV(C)
or UV(D65) conditions prior to switching to the UVex(420) mode, but it is considered that this uncertainty in the
residual level can be ignored in the application of this document.
NOTE 2 Although this method is restricted to paper, it can be applied to pulp sheets, although this is not in
accordance with this document. In general, when pulps are tested, the light-absorption coefficient at 457 nm
corresponding to the ISO brightness value or the spectral absorption coefficients are of greater interest than the
weighted value standardized in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 186, Paper and board — Sampling to determine average quality
ISO 187, Paper, board and pulps — Standard atmosphere for conditioning and testing and procedure for
monitoring the atmosphere and conditioning of samples
ISO 536, Paper and board — Determination of grammage
ISO 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso. org/o bp
— IEC Electropedia: available at http:// www.e lectropedia. org/
© ISO 2017 – All rights reserved 1
---------------------- Page: 9 ----------------------
oSIST ISO 9416:2018
ISO 9416:2017(E)
3.1
reflectance factor
R
ratio of the radiation reflected by a surface element of a body, in the direction delimited by a given cone
with its apex at the surface element, to that reflected by the perfect reflecting diffuser under the same
conditions of irradiation
Note 1 to entry: The ratio is often expressed as a percentage.
3.2
luminance factor (C)
R
y
reflectance factor (3.1) defined with reference to the visual efficiency function V()λ and the CIE
illuminant C
Note 1 to entry: The visual efficiency function describes the sensitivity of the eye to light, so that the luminance
factor corresponds to the attribute of visual perception of the reflecting surface.
Note 2 to entry: For computational purposes, the V()λ function is identical to the CIE 1931 colour matching
function y()λ .
3.3
single-sheet luminance factor (C)
R
y,0
luminance factor (C) (3.2) of a single sheet of paper with a black cavity as backing
3.4
intrinsic luminance factor (C)
R
y,∞
luminance factor (C) (3.2) of a layer or pad of material thick enough to be opaque, i.e. such that increasing
the thickness of the pad by doubling the number of sheets results in no change in the measured
reflectance factor
[SOURCE: ISO 2471:2008, 3.4]
3.5
opacity (paper backing)
ratio of the single-sheet luminance factor (C), R , (3.3) to the intrinsic luminance factor (C), R , (3.4) of
y,0 y,∞
the same sample
Note 1 to entry: The opacity is expressed as a percentage.
3.6
light-absorption coefficient
k
fraction of the spectral radiant flux diffusely incident on a differential layer within a material that is
absorbed when the flux passes through the layer, divided by the thickness of the layer
Note 1 to entry: The flux referred to is a radiant flux across the differential layer.
3.7
light-scattering coefficient
s
fraction of the spectral radiant flux diffusely incident on a differential layer within a material that is
reflected when the flux passes through the layer, divided by the thickness of the layer
Note 1 to entry: The flux referred to is a radiant flux across the differential layer.
Note 2 to entry: It is assumed that no reflection occurs at the boundaries of the material.
2 © ISO 2017 – All rights reserved
---------------------- Page: 10 ----------------------
oSIST ISO 9416:2018
ISO 9416:2017(E)
Note 3 to entry: In a two-flux system, the scattering coefficient is equal to the net transfer of flux from the
stronger flux to the weaker flux in a differential layer within a material divided by the product of the thickness of
the layer and the difference between the fluxes (see ISO 186).
3.8
light-scattering coefficient by reflectance factor measurements
s
y
coefficient calculated by application of the Kubelka-Munk equations to
luminance factor data weighted with respect to the CIE illuminant C, obtained in an instru
...
SLOVENSKI STANDARD
SIST ISO 9416:2018
01-september-2018
1DGRPHãþD
SIST ISO 9416:2011
3DSLU'RORþDQMHNRHILFLHQWDVLSDQMDLQNRHILFLHQWDDEVRUSFLMHVYHWOREH XSRUDED
WHRULMHSR.XEHOND0XQNX
Paper -- Determination of light scattering and absorption coefficients (using Kubelka-
Munk theory)
Papier -- Détermination des coefficients de diffusion et d'absorption de la lumière
(utilisation de la théorie de Kubelka-Munk)
Ta slovenski standard je istoveten z: ISO 9416:2017
ICS:
85.060 Papir, karton in lepenka Paper and board
SIST ISO 9416:2018 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 9416:2018
---------------------- Page: 2 ----------------------
SIST ISO 9416:2018
INTERNATIONAL ISO
STANDARD 9416
Third edition
2017-05
Paper — Determination of light
scattering and absorption coefficients
(using Kubelka-Munk theory)
Papier — Détermination des coefficients de diffusion et d’absorption
de la lumière (utilisation de la théorie de Kubelka-Munk)
Reference number
ISO 9416:2017(E)
©
ISO 2017
---------------------- Page: 3 ----------------------
SIST ISO 9416:2018
ISO 9416:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 9416:2018
ISO 9416:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus . 3
6 Sampling and conditioning . 4
7 Preparation of test pieces . 4
8 Procedure. 4
9 Calculation of results . 5
10 Test report . 5
Annex A (informative) Spectral characteristics of reflectometers for measuring luminance factor 6
Annex B (informative) Precision .10
Bibliography .11
© ISO 2017 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 9416:2018
ISO 9416:2017(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps.
This third edition cancels and replaces the second edition (ISO 9416:2009), which has been technically
revised, to allow for calculations to use ASTM E308 for instruments that have bandpass correction and
still maintain the procedure for instruments without bandpass correction.
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Introduction
The opacity of a paper is dependent on its grammage, but it is also intrinsically dependent on the light-
absorption and light-scattering coefficients of the material. These coefficients are calculated from the
values of the reflectance factor over a black backing, the intrinsic reflectance factor and the grammage
of the sheet.
The calculation of these coefficients requires luminance factor data obtained by measurement under
specified conditions. Apart from the optical properties of the sample, the luminance factor depends on
the conditions of measurement and particularly on the spectral and geometric characteristics of the
instrument used for its determination. This document is therefore intended to be read in conjunction
with ISO 2469 and ISO 2471.
NOTE This method is based on a theory developed by Kubelka and Munk. This theory describes scattering
and absorption processes with certain approximations and simplifications and can therefore yield questionable
results in extreme cases. However, the Kubelka-Munk theory offers a simple method for determining these
coefficients with the instrument used for the determination of optical properties of paper and pulps. Moreover,
the method based on this theory has been successfully used in practical applications.
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INTERNATIONAL STANDARD ISO 9416:2017(E)
Paper — Determination of light scattering and absorption
coefficients (using Kubelka-Munk theory)
1 Scope
This document specifies a method for the calculation of light-scattering and light-absorption coefficients
based upon diffuse reflectance measurements made under the conditions specified in ISO 2469 using
the colour matching function ȳ(λ) and CIE illuminant C.
It is emphasized that the strict evaluation of the light-scattering and light-absorption coefficients
requires conditions which cannot be achieved with the instrumentation specified here. The values
obtained by application of this document are dependent on the application of the Kubelka-Munk
equations, not to full reflectance data but to reflectance factor data obtained using the specified d/0°
geometry and a gloss trap.
The use of the method is restricted to white and near-white uncoated papers with an opacity less
than about 95 %. Paper that has been treated with a fluorescent dyestuff or that exhibits significant
fluorescence can only be dealt with if a filter with a cut-off wavelength of 420 nm is used to eliminate all
the fluorescence effect in the UVex(420) mode.
NOTE 1 The residual UV-level in the instrument may depend on whether the instrument is adjusted to UV(C)
or UV(D65) conditions prior to switching to the UVex(420) mode, but it is considered that this uncertainty in the
residual level can be ignored in the application of this document.
NOTE 2 Although this method is restricted to paper, it can be applied to pulp sheets, although this is not in
accordance with this document. In general, when pulps are tested, the light-absorption coefficient at 457 nm
corresponding to the ISO brightness value or the spectral absorption coefficients are of greater interest than the
weighted value standardized in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 186, Paper and board — Sampling to determine average quality
ISO 187, Paper, board and pulps — Standard atmosphere for conditioning and testing and procedure for
monitoring the atmosphere and conditioning of samples
ISO 536, Paper and board — Determination of grammage
ISO 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
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3.1
reflectance factor
R
ratio of the radiation reflected by a surface element of a body, in the direction delimited by a given cone
with its apex at the surface element, to that reflected by the perfect reflecting diffuser under the same
conditions of irradiation
Note 1 to entry: The ratio is often expressed as a percentage.
3.2
luminance factor (C)
R
y
reflectance factor (3.1) defined with reference to the visual efficiency function V()λ and the CIE
illuminant C
Note 1 to entry: The visual efficiency function describes the sensitivity of the eye to light, so that the luminance
factor corresponds to the attribute of visual perception of the reflecting surface.
Note 2 to entry: For computational purposes, the V()λ function is identical to the CIE 1931 colour matching
function y()λ .
3.3
single-sheet luminance factor (C)
R
y,0
luminance factor (C) (3.2) of a single sheet of paper with a black cavity as backing
3.4
intrinsic luminance factor (C)
R
y,∞
luminance factor (C) (3.2) of a layer or pad of material thick enough to be opaque, i.e. such that increasing
the thickness of the pad by doubling the number of sheets results in no change in the measured
reflectance factor
[SOURCE: ISO 2471:2008, 3.4]
3.5
opacity (paper backing)
ratio of the single-sheet luminance factor (C), R , (3.3) to the intrinsic luminance factor (C), R , (3.4) of
y,0 y,∞
the same sample
Note 1 to entry: The opacity is expressed as a percentage.
3.6
light-absorption coefficient
k
fraction of the spectral radiant flux diffusely incident on a differential layer within a material that is
absorbed when the flux passes through the layer, divided by the thickness of the layer
Note 1 to entry: The flux referred to is a radiant flux across the differential layer.
3.7
light-scattering coefficient
s
fraction of the spectral radiant flux diffusely incident on a differential layer within a material that is
reflected when the flux passes through the layer, divided by the thickness of the layer
Note 1 to entry: The flux referred to is a radiant flux across the differential layer.
Note 2 to entry: It is assumed that no reflection occurs at the boundaries of the material.
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Note 3 to entry: In a two-flux system, the scattering coefficient is equal to the net transfer of flux from the
stronger flux to the weaker flux in a differential layer within a material divided by the product of the thickness of
the layer and the difference between the fluxes (see ISO 186).
3.8
light-scattering coefficient by reflectance factor measurements
s
y
coefficient calculated by application of the Kubelka-Munk equations to
luminance factor data weighted with respect to the CIE illuminant C, ob
...
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