Tissue paper and tissue products - Part 15: Determination of optical properties - Measurement of brightness and colour with C/2° (indoor daylight) illuminant (ISO 12625-15:2022)

This document specifies testing procedures for the instrumental determination of brightness and
colour of tissue paper and tissue products viewed in indoor daylight conditions. It also gives specific
instructions for the preparation of test pieces (single-ply, multi-ply products) and for the optical
measurements of products, where special precautions can be necessary.
NOTE The properties called D65 brightness and colour are measured with an instrument adjusted to a much
higher UV content than that specified in this document.

Tissue-Papier und Tissue-Produkte - Teil 15: Bestimmung von optischen Eigenschaften - Messung von Brightness und Farbe unter Lichtart C/2° (Tageslichtbedingungen in Innenräumen) (ISO 12625‑15:2022)

Dieses Dokument legt Prüfverfahren für die instrumentelle Bestimmung von Brightness und Farbe von Tissue-Papier und Tissue-Produkten unter Tageslichtbedingungen in Innenräumen fest. Es werden auch spezifische Anweisungen für die Vorbereitung von Proben (einlagige, mehrlagige Produkte) und für die optischen Messungen von Produkten gegeben, bei denen besondere Vorsichtsmaßnahmen notwendig sein können.
ANMERKUNG   Die als D65 Brightness und  Farbe bezeichneten Eigenschaften werden mit einem Messgerät gemessen, das auf einen viel höheren UV Anteil angepasst ist, als in diesem Dokument festgelegt wird.

Papier tissue et produits tissue - Partie 15: Détermination des propriétés optiques - Mesurage du degré de blancheur et de la couleur avec l'illuminant C/2° (lumière du jour à l'intérieur) (ISO 12625-15:2022)

Le présent document spécifie des modes opératoires d’essai pour la détermination instrumentale du degré de blancheur et de la couleur des papiers tissue et des produits tissue observés dans des conditions de lumière du jour à l’intérieur. Il donne également des instructions spécifiques pour la préparation des éprouvettes (produits à pli unique, produits multiplis) ainsi que pour les mesures optiques des produits, lorsque des précautions particulières peuvent se révéler nécessaires.
NOTE      Les propriétés appelées « degré de blancheur D65 et couleur » sont mesurées à l’aide d’un appareil réglé sur une teneur en UV beaucoup plus élevée que celle spécifiée dans le présent document.

Tissue papir in proizvodi iz tissue papirja - 15. del: Ugotavljanje optičnih lastnosti - Merjenje beline in barve s svetilom C/2° (osvetlitev v prostoru) (ISO 12625‑15:2022)

Ta dokument določa preskusne postopke za instrumentalno določevanje svetlosti in barve tissue papirja ter proizvodov iz tissue papirja, opazovanih pri dnevni svetlobi v notranjih prostorih. Določa tudi posebna navodila za pripravo preskusnih vzorcev (proizvodi z enim slojem, več sloji) in za optično merjenje proizvodov, pri čemer so morda potrebni posebni zaščitni ukrepi.
OPOMBA: Lastnosti, imenovane D65, svetlost in barva, se merijo z instrumentom, prilagojenim na veliko večjo UV-vsebnost od vsebnosti, opredeljene v tem dokumentu.

General Information

Status
Published
Public Enquiry End Date
30-Mar-2022
Publication Date
07-Dec-2022
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Dec-2022
Due Date
05-Feb-2023
Completion Date
08-Dec-2022

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SLOVENSKI STANDARD
SIST EN ISO 12625-15:2023
01-januar-2023
Nadomešča:
SIST EN ISO 12625-15:2015
Tissue papir in proizvodi iz tissue papirja - 15. del: Ugotavljanje optičnih lastnosti -
Merjenje beline in barve s svetilom C/2° (osvetlitev v prostoru) (ISO
12625‑15:2022)
Tissue paper and tissue products - Part 15: Determination of optical properties -
Measurement of brightness and colour with C/2° (indoor daylight) illuminant (ISO 12625-
15:2022)
Tissue-Papier und Tissue-Produkte - Teil 15: Bestimmung von optischen Eigenschaften -
Messung von Brightness und Farbe unter Lichtart C/2° (Tageslichtbedingungen in
Innenräumen) (ISO 12625‑15:2022)
Papier tissue et produits tissue - Partie 15: Détermination des propriétés optiques -
Mesurage du degré de blancheur et de la couleur avec l'illuminant C/2° (lumière du jour
à l'intérieur) (ISO 12625-15:2022)
Ta slovenski standard je istoveten z: EN ISO 12625-15:2022
ICS:
85.080.20 Tissue papir Tissue paper
SIST EN ISO 12625-15:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 12625-15:2023

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SIST EN ISO 12625-15:2023


EN ISO 12625-15
EUROPEAN STANDARD

NORME EUROPÉENNE

October 2022
EUROPÄISCHE NORM
ICS 85.080.20 Supersedes EN ISO 12625-15:2015
English Version

Tissue paper and tissue products - Part 15: Determination
of optical properties - Measurement of brightness and
colour with C/2° (indoor daylight) illuminant (ISO 12625-
15:2022)
Papier tissue et produits tissue - Partie 15: Tissue-Papier und Tissue-Produkte - Teil 15:
Détermination des propriétés optiques - Mesurage du Bestimmung von optischen Eigenschaften - Messung
degré de blancheur et de la couleur avec l'illuminant von Brightness und Farbe unter LichtartC/2°
C/2° (lumière du jour à l'intérieur) (ISO 12625- (Tageslichtbedingungen in Innenräumen) (ISO 12625-
15:2022) 15:2022)
This European Standard was approved by CEN on 7 October 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12625-15:2022 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
SIST EN ISO 12625-15:2023
EN ISO 12625-15:2022 (E)
Contents Page
European foreword . 3

2

---------------------- Page: 4 ----------------------
SIST EN ISO 12625-15:2023
EN ISO 12625-15:2022 (E)
European foreword
This document (EN ISO 12625-15:2022) has been prepared by Technical Committee ISO/TC 6 "Paper,
board and pulps" in collaboration with Technical Committee CEN/TC 172 “Pulp, paper and board” the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2023, and conflicting national standards shall be
withdrawn at the latest by April 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 12625-15:2015.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 12625-15:2022 has been approved by CEN as EN ISO 12625-15:2022 without any
modification.


3

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SIST EN ISO 12625-15:2023

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SIST EN ISO 12625-15:2023
INTERNATIONAL ISO
STANDARD 12625-15
Second edition
2022-10
Tissue paper and tissue products —
Part 15:
Determination of optical properties —
Measurement of brightness and colour
with C/2° (indoor daylight) illuminant
Papier tissue et produits tissue —
Partie 15: Détermination des propriétés optiques — Mesurage du
degré de blancheur et de la couleur avec l'illuminant C/2° (lumière du
jour à l'intérieur)
Reference number
ISO 12625-15:2022(E)
© ISO 2022

---------------------- Page: 7 ----------------------
SIST EN ISO 12625-15:2023
ISO 12625-15:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2022 – All rights reserved

---------------------- Page: 8 ----------------------
SIST EN ISO 12625-15:2023
ISO 12625-15:2022(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 Calibration .4
7 Sampling . 4
8 Conditioning . 5
9 Preparation of test pieces .5
10 Procedure .5
10.1 General . 5
10.2 Measurement of ISO brightness . 5
10.3 Measurement of colour (C/2°) . 5
11 Calculation . 6
11.1 ISO brightness . 6
11.2 Colour C/2° . . 6
11.2.1 Single values . 6
11.2.2 Mean value . 6
11.2.3 Dispersion of the results . 7
12 Test report . 7
Annex A (informative) Precision . 8
Bibliography .10
iii
© ISO 2022 – All rights reserved

---------------------- Page: 9 ----------------------
SIST EN ISO 12625-15:2023
ISO 12625-15:2022(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 of 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
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee
SC 2, Test methods and quality specifications for paper and board, in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 172, Pulp, paper and board, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 12625-15:2015), which has been
technically revised.
The main changes are as follows:
— removed alternative formulae in 11.2.1 because they are not relevant for tissue paper;
— updated tables in Annex A to include data to 0,01 and corrected errors in the tables;
— changed C/2° Brightness to ISO Brightness.
A list of all parts in the ISO 12625 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
  © ISO 2022 – All rights reserved

---------------------- Page: 10 ----------------------
SIST EN ISO 12625-15:2023
ISO 12625-15:2022(E)
Introduction
Brightness and colour measurement can be performed under various illumination and observation
conditions. This document deals with C/2° conditions, which refer to an indoor daylight.
D65/10° conditions (outdoor daylight) are considered in ISO 12625-7. Although both International
Standards deal with brightness and colour, results obtained are usually different and do not correlate.
Optical measurements are affected by the geometry of the instruments used and by the texture of the
material.
The optical properties are related to the visual appearance of the material in a specified illumination
condition. Although optical properties are intrinsic properties of tissue paper, they are not functional
properties.
Brightness should not be confused with the optical property called CIE-whiteness, which is based on
reflectance data obtained over the full visible spectral range (VIS). In contrast, brightness is limited to
the blue region of VIS (visible spectrum).
As preferences for the properties specified can vary by country/market, two other test methods for
the determination of optical properties were developed in addition to this document: ISO 12625-7 and
ISO 12625-16.
v
© ISO 2022 – All rights reserved

---------------------- Page: 11 ----------------------
SIST EN ISO 12625-15:2023

---------------------- Page: 12 ----------------------
SIST EN ISO 12625-15:2023
INTERNATIONAL STANDARD ISO 12625-15:2022(E)
Tissue paper and tissue products —
Part 15:
Determination of optical properties — Measurement
of brightness and colour with C/2° (indoor daylight)
illuminant
1 Scope
This document specifies testing procedures for the instrumental determination of brightness and
colour of tissue paper and tissue products viewed in indoor daylight conditions. It also gives specific
instructions for the preparation of test pieces (single-ply, multi-ply products) and for the optical
measurements of products, where special precautions can be necessary.
NOTE The properties called D65 brightness and colour are measured with an instrument adjusted to a much
higher UV content than that specified 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 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)
ISO 2470-1:2016, Paper, board and pulps — Measurement of diffuse blue reflectance factor — Part 1:
Indoor daylight conditions (ISO brightness)
ISO 2470-2, Paper, board and pulps — Measurement of diffuse blue reflectance factor — Part 2: Outdoor
daylight conditions (D65 brightness)
ISO/CIE 11664-4, Colorimetry — Part 4: CIE 1976 L*a*b* colour space
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
1
© ISO 2022 – All rights reserved

---------------------- Page: 13 ----------------------
SIST EN ISO 12625-15:2023
ISO 12625-15:2022(E)
3.1
diffuse radiance factor
R
ratio of the radiation reflected and emitted from a body to that reflected from the perfect reflecting
diffuser under the same conditions of diffuse illumination and normal detection
Note 1 to entry: The ratio is often expressed as a percentage.
[SOURCE: ISO 2469:2014, 3.2]
3.2
intrinsic diffuse radiance factor
R

diffuse radiance factor (3.1) 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 radiance factor
Note 1 to entry: The ratio is often expressed as a percentage.
Note 2 to entry: The radiance factor of a single non-opaque sheet is dependent on the background and is not a
material property.
[SOURCE: ISO 2469:2014, 3.3, modified — Note 2 to entry added.]
3.3
reflectance factor
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 illumination
Note 1 to entry: The ratio is often expressed as a percentage.
Note 2 to entry: This term shall only be used when it is known that the test material exhibits no luminescence
(fluorescence).
[SOURCE: CIE S 017 ILV: 2020, 17-24-070]
3.4
ISO brightness
intrinsic diffuse radiance factor (3.2) measured with a reflectometer having the characteristics described
in ISO 2469, equipped with a f
...

SLOVENSKI STANDARD
oSIST prEN ISO 12625-15:2022
01-marec-2022
Tissue papir in proizvodi iz tissue papirja - 15. del: Ugotavljanje optičnih lastnosti -
Merjenje beline in barve s svetilom C/2° (osvetlitev v prostoru) (ISO/DIS 12625-
15:2022)
Tissue paper and tissue products - Part 15: Determination of optical properties -
Measurement of brightness and colour with C/2° (indoor daylight) illuminant (ISO/DIS
12625-15:2022)
Tissue-Papier und Tissue-Produkte – Teil15: Bestimmung von optischen Eigenschaften
– Messung von Brightness und Farbe unter LichtartC/2° (Tageslichtbedingungen in
Innenräumen) (ISO/DIS 12625-15:2022)
Papier tissue et produits tissue - Partie 15: Détermination des propriétés optiques -
Mesurage du degré de blancheur et de la couleur avec l'illuminant C/2° (lumière du jour
à l'intérieur) (ISO/DIS 12625-15:2022)
Ta slovenski standard je istoveten z: prEN ISO 12625-15
ICS:
85.080.20 Tissue papir Tissue paper
oSIST prEN ISO 12625-15:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 12625-15:2022

---------------------- Page: 2 ----------------------
oSIST prEN ISO 12625-15:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 12625-15
ISO/TC 6/SC 2 Secretariat: SIS
Voting begins on: Voting terminates on:
2022-01-10 2022-04-04
Tissue paper and tissue products —
Part 15:
Determination of optical properties — Measurement
of brightness and colour with C/2° (indoor daylight)
illuminant
Papier tissue et produits tissue —
Partie 15: Détermination des propriétés optiques — Mesurage du degré de blancheur et de la couleur avec
l'illuminant C/2° (lumière du jour à l'intérieur)
ICS: 85.080.20
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 12625-15:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022

---------------------- Page: 3 ----------------------
oSIST prEN ISO 12625-15:2022
ISO/DIS 12625-15:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2022 – All rights reserved

---------------------- Page: 4 ----------------------
oSIST prEN ISO 12625-15:2022
ISO/DIS 12625-15:2022(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
5.1 Reflectometer or spectrophotometer . 3
5.2 Reference standard for calibration of the instrument . 3
5.3 Working standards . 4
6 Calibration .4
7 Sampling . 4
8 Conditioning . 5
9 Preparation of test pieces .5
10 Procedure .5
10.1 General . 5
10.2 Measurement of ISO brightness . 5
10.3 Measurement of (C/2°) colour . 6
11 Calculation . 6
11.1 ISO brightness . 6
11.2 C/2° Colour . . 6
11.2.1 Single values . 6
11.2.2 Mean value . 6
11.2.3 Dispersion of the results . 7
12 Test report . 7
Annex A (informative) Precision . 8
Bibliography .10
iii
© ISO 2022 – All rights reserved

---------------------- Page: 5 ----------------------
oSIST prEN ISO 12625-15:2022
ISO/DIS 12625-15:2022(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 of 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
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee
SC 2, Test methods and quality specifications for paper and board.
This second edition cancels and replaces the first edition (ISO 12625-15:2015), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— removing alternative equations in clause 11.2.1 because they are not relevant for tissue paper.
— updated tables in Annex A to include L*, a*, b* data to 0,01 and correct errors in the tables
— changing C/2° Brightness to ISO Brightness
A list of all parts in the ISO 12625 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
  © ISO 2022 – All rights reserved

---------------------- Page: 6 ----------------------
oSIST prEN ISO 12625-15:2022
ISO/DIS 12625-15:2022(E)
Introduction
Brightness and colour measurement may be performed under various illumination and observation
conditions. This part of ISO 12625 deals with C/2° conditions, which refer to an indoor daylight.
D65/10° conditions (outdoor daylight) are considered in ISO 12625-7. Although both standards deal
with brightness and colour, results obtained are usually different and do not correlate.
Optical measurements are affected by the geometry of the instruments used and by the texture of the
material. The design of the instrument to be used according to this part of ISO 12625, and the routine to
be adopted for its calibration are specified in ISO 2469 and ISO 2470-1.
The optical properties are related to the visual appearance of the material in a specified illumination
condition. Although optical properties are intrinsic properties of tissue paper, they are not functional
properties.
Brightness is not to be confused with the optical property called CIE-whiteness, which is based on
reflectance data obtained over the full visible spectral range (VIS). In contrast, brightness is limited to
the blue region of VIS (visible spectrum).
As preferences for the properties to be specified can vary by country/market, three different test
methods for the determination of optical properties were developed:
a) Part 7: Determination of optical properties — Measurement of brightness and colour with D65/10°
(outdoor daylight);
b) Part 15: Determination of optical properties — Measurement of brightness and colour with C/2°
(indoor daylight);
c) Part 16: Determination of optical properties — Measurement of opacity (paper backing) — Diffuse
reflectance method.
v
© ISO 2022 – All rights reserved

---------------------- Page: 7 ----------------------
oSIST prEN ISO 12625-15:2022

---------------------- Page: 8 ----------------------
oSIST prEN ISO 12625-15:2022
DRAFT INTERNATIONAL STANDARD ISO/DIS 12625-15:2022(E)
Tissue paper and tissue products —
Part 15:
Determination of optical properties — Measurement
of brightness and colour with C/2° (indoor daylight)
illuminant
1 Scope
This part of ISO 12625 specifies testing procedures for the instrumental determination of brightness
and colour of tissue paper and tissue products viewed in indoor daylight conditions. It also gives
specific instructions for the preparation of test pieces (single-ply, multi-ply products) and for the optical
measurements of products, where special precautions may be necessary.
NOTE The properties called D65 brightness and colour are measured with an instrument adjusted to a much
higher UV content than that specified in this part of ISO 12625. The measurements of D65 brightness and colour
are described in ISO 12625-7.
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 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)
ISO 2470-1:2016, Paper, board and pulps — Measurement of diffuse blue reflectance factor — Part 1:
Indoor daylight conditions (ISO brightness)
ISO 4094, Paper, board and pulps — General requirements for the competence of laboratories authorized
for the issue of optical reference transfer standards of level 3
ISO 5631-1:2015, Paper and board — Determination of colour by diffuse reflectance — Part 1: Indoor
daylight conditions (C/2 degrees)
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 https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
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© ISO 2022 – All rights reserved

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oSIST prEN ISO 12625-15:2022
ISO/DIS 12625-15:2022(E)
3.1
diffuse radiance factor
R
ratio of the radiation reflected and emitted from a body to that reflected from the perfect reflecting
diffuser under the same conditions of diffuse illumination and normal detection
Note 1 to entry: The reflectance factor is expressed as a percentage.
[SOURCE: ISO 2469:2014, definition 3.2]
3.2
intrinsic diffuse radiance factor
R

diffuse radiance factor 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 radiance
factor
Note 1 to entry: The ratio is often expressed as a percentage.
Note 2 to entry: The radiance factor of a single non-opaque sheet is dependent on the background and is not a
material property.
[SOURCE: ISO 2469:2014, definition 3.3]
3.3
reflectance factor
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 illumination
Note 1 to entry: The ratio is often expressed as a percentage.
Note 2 to entry: This term may be used only when it is known that the test material exhibits no luminescence
(fluorescence).
[SOURCE: ISO 2469:2014, definition 3.4]
3.4
ISO brightness
intrinsic reflectance factor measured with a reflectometer having the characteristics described in
ISO 2469, equipped with a filter or corresponding function having an effective wavelength of 457 nm
(and a half bandwidth of 44 nm, and adjusted so that the UV content of the irradiation incident upon the
test piece corresponds to that of the CIE illuminant C
Note 1 to entry: The filter function is described more fully by the weighing function factors given in ISO 2470-1.
3.5
tristimulus values
X, Y, Z
amount of the three reference colour stimuli, in a given chromatic system, required to match the
stimulus considered
Note 1 to entry: In this part of 12625 as in ISO 5631-1, the CIE illuminant C and the CIE 1931 (2°) standard
observer are used to define the trichromatic system.
Note 2 to entry: No subscript is applied to conform to the CIE convention that tristimulus values have no subscript
when the CIE 1931 (2°)
...

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