SIST EN ISO 6504-1:2019

SLOVENSKI STANDARD
01-september-2019
Nadomešča:
SIST EN ISO 6504-1:2006
Barve in laki - Ugotavljanje kritnosti - 1. del: Metoda po Kubelka-Munku za bele in
pastelne nianse (ISO 6504-1:2019)
Paints and varnishes - Determination of hiding power - Part 1: Kubelka-Munk method for
white and light-coloured paints (ISO 6504-1:2019)
Beschichtungsstoffe - Bestimmung des Deckvermögens - Teil 1: Verfahren nach
Kubelka-Munk für weiße und helle Beschichtungen (ISO 6504-1:2019)
Peintures et vernis - Détermination du pouvoir masquant - Partie 1: Méthode de
Kubelka-Munk pour les peintures blanches et les peintures claires (ISO 6504-1:2019)
Ta slovenski standard je istoveten z: EN ISO 6504-1:2019
ICS:
87.040 Barve in laki Paints and varnishes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 6504-1
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2019
EUROPÄISCHE NORM
ICS 87.040 Supersedes EN ISO 6504-1:2006
English Version
Paints and varnishes - Determination of hiding power -
Part 1: Kubelka-Munk method for white and light-coloured
paints (ISO 6504-1:2019)
Peintures et vernis - Détermination du pouvoir Beschichtungsstoffe - Bestimmung des Deckvermögens
masquant - Partie 1: Méthode de Kubelka-Munk pour - Teil 1: Verfahren nach Kubelka-Munk für weiße und
les peintures blanches et les peintures claires (ISO helle Beschichtungen (ISO 6504-1:2019)
6504-1:2019)
This European Standard was approved by CEN on 13 May 2019.

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, North
Macedonia, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey 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
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6504-1:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 6504-1:2019) has been prepared by Technical Committee ISO/TC 35 "Paints
and varnishes" in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes” 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 December 2019, and conflicting national standards
shall be withdrawn at the latest by December 2019.
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 6504-1:2006.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 6504-1:2019 has been approved by CEN as EN ISO 6504-1:2019 without any
modification.
INTERNATIONAL ISO
STANDARD 6504-1
Second edition
2019-05
Paints and varnishes — Determination
of hiding power —
Part 1:
Kubelka-Munk method for white and
light-coloured paints
Peintures et vernis — Détermination du pouvoir masquant —
Partie 1: Méthode de Kubelka-Munk pour les peintures blanches et les
peintures claires
Reference number
ISO 6504-1:2019(E)
©
ISO 2019
ISO 6504-1:2019(E)
© ISO 2019
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
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Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 6504-1:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Kubelka-Munk equations . 2
6 Apparatus and materials. 3
6.1 Substrates . 3
6.1.1 Determination of R . 3
B
6.1.2 Determination of R . 4
∞
6.2 Film applicators . 4
6.3 Reflectometer . 4
6.4 Template . 4
7 Limitations . 4
8 Sampling . 4
9 Procedure. 4
9.1 Determination of R . 4
∞
9.2 Determination of R . 5
B
9.2.1 Preparation of test films . 5
9.2.2 Measurement of reflectance R . 5
B
9.3 Determination of film thickness . 6
9.3.1 General. 6
9.3.2 Method using polyester film . 6
9.3.3 Method using black glass plates . 6
10 Expression of results . 6
10.1 Calculation of wet film thickness . 6
10.2 Calculation of hiding power . 7
11 Precision . 7
11.1 Repeatability (r) . 7
11.2 Reproducibility (R) . 7
12 Test report . 7
Annex A (informative) Graphs for determination of St from R and R for R = 0,80 .8
B ∞ g
Annex B (informative) Table of values of reflectivity R and factor α for R = 0,80 .33
∞ g
Annex C (informative) Examples of the calculation of hiding power from measurements of
R and R .34
B ∞
Bibliography .36
ISO 6504-1:2019(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 35, Paints and varnishes, Subcommittee
SC 9, General test method for paints and varnishes.
This second edition cancels and replaces the first edition (ISO 6504-1:1983), which has been technically
revised. The main changes compared to the previous edition are as follows:
a) the normative references in Clause 2 have been updated;
b) Clause 3 for terms and definitions has been added;
c) Clause 7 for limitations has been added;
d) the term "contrast ratio" has been changed to "hiding power" throughout the text;
e) it has been clarified that the reflectance R needs to be measured and that the graphs in Annex A
g
and values in Table B.1 are only examples for R = 0,80.
g
A list of all parts in the ISO 6504 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 2019 – All rights reserved

ISO 6504-1:2019(E)
Introduction
[1]
ISO 6504-3 specifies a method for determining the hiding power of paints at a fixed spreading rate,
by applying paint films to black and white charts and to polyester film respectively. It depends on the
observation that there is a linear relationship between hiding power and reciprocal film thickness, at
least over a limited range of film thickness.
Hiding power of paints is generally defined as the spreading rate required to give a hiding power of
[1]
98 %. To determine this by the method specified in ISO 6504-3 would be time-consuming and require
considerable extrapolation which often exceeds the limit of linearity of the relationship between hiding
power and spreading rate. Therefore, this method for the determination of hiding power, involving
the Kubelka-Munk (K-M) equations which relate scattering and absorption coefficients to optical
properties, has also been standardized.
INTERNATIONAL STANDARD ISO 6504-1:2019(E)
Paints and varnishes — Determination of hiding power —
Part 1:
Kubelka-Munk method for white and light-coloured paints
1 Scope
This document specifies a method for determining the hiding power (spreading rate necessary to give
a hiding power of 98 %) of white or light-coloured paints. It is applicable to paint films having the tri-
stimulus value of Y ≥ 70 and hiding power > 80 %. It is not applicable to fluorescent or metallic paints.
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 1513, Paints and varnishes — Examination and preparation of test samples
ISO 2808, Paints and varnishes — Determination of film thickness
ISO 2811-1, Paints and varnishes — Determination of density — Part 1: Pycnometer method
ISO 3251, Paints, varnishes and plastics — Determination of non-volatile-matter content
ISO 4618, Paints and varnishes — Terms and definitions
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
light-coloured paint
coating with tristimulus values Y and Y greater than 25, measured with a spectrophotometer on a
black and white substrate
4 Principle
The method is based on the Kubelka and Munk equations relating the scattering and absorption
coefficients of pigmented films to their colour and opacity.
For the determination of hiding power, both the reflectance (R ) of a paint film of thickness t on a black
B
background and the reflectivity (R ) are required for introduction into the Kubelka-Munk equations
∞
(Clause 5).
ISO 6504-1:2019(E)
5 Kubelka-Munk equations
The Kubelka-Munk (K-M) equations required are
 
1 1
aR=+ (1)
 
∞
2 R
 ∞ 
ba=−R (2)
∞
R = (3)
B
ab+ cothbSt
1−−Ra bbcoth St
()
g
R= (4)
ab+−cothbStR
g
where
R is the reflectivity, i.e. the reflectance of a paint film of such thickness that further increase in
∞
thickness gives no further change in reflectance;
R is the reflectance of a paint film of thickness t applied over a black background;
B
R is the reflectance of a paint film of thickness t applied over a white background of determined
reflectance R ;
g
−1
S is the scattering coefficient per micrometre (µm );
t is the thickness, in micrometres, of the paint film.
When using Formulae (1) to (4) with this method, the measured CIE tristimulus values Y divided by 100
are inserted for R, R and R , respectively.
B ∞
The hiding power V is the spreading rate necessary to give a hiding power (R /R) of 0,98, and is
0,98 B
determined via the equivalent film thickness t according to the formula
0,98
V =
t
where
V is the hiding power, in square metres per litre;
t is the thickness, in micrometres, of the wet paint film.

2 © ISO 2019 – All rights reserved

ISO 6504-1:2019(E)
From Formulae (3) and (4), when the hiding power (R /R) is equal to 0,98
B
ab−+08, cothbSt
09, 8
=09, 8
   
ab+ cothbSta10−−,c8 bboth St
{}
09,,80 98
   
or after, rearrangement
 
1 0,02+ D
t = arcoth (5)
 
09, 8
 
bS 1,568 b
 
where
D = 3,136 a [1 − 0,98(1 − 0,8a)] − 2,508 4
and
1000 1000bS
V == =∝S (6)
t  
00, 2+ D
arcoth
 
 
1,568b
 
NOTE 1 If y = coth x, x = arcoth y.
NOTE 2 It can be seen that for constant values of R and hiding power (V ), factor α is a function of R .
g 0,98 ∞
The scattering coefficient S is determined from a rearrangement of Formula (3), the values of a and b
being known by calculation from Formulae (1) and (2) respectively, as follows:
1−aR 
B
St = arcoth (7)
 
b bR
B
 
To simplify the calculations, graphs are available for the determination of the product St from measured
value
...