SIST EN ISO 7783:2012

SLOVENSKI STANDARD
SIST EN ISO 7783:2012
01-januar-2012
1DGRPHãþD
SIST EN ISO 7783-1:1999
SIST EN ISO 7783-2:1999
%DUYHLQODNL8JRWDYOMDQMHSUHSXVWQRVWLYRGQHSDUH0HWRGDVþDãR,62

Paints and varnishes - Determination of water-vapour transmission properties - Cup
method (ISO 7783:2011)
Beschichtungsstoffe - Bestimmung der Wasserdampfdurchlässigkeit - Schalenverfahren
(ISO 7783:2011)
Peintures et vernis - Détermination du coefficient de transmission de la vapeur d'eau -
Méthode au cylindre (ISO 7783:2011)
Ta slovenski standard je istoveten z: EN ISO 7783:2011
ICS:
87.040 Barve in laki Paints and varnishes
SIST EN ISO 7783:2012 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 7783:2012

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SIST EN ISO 7783:2012


EUROPEAN STANDARD
EN ISO 7783

NORME EUROPÉENNE

EUROPÄISCHE NORM
November 2011
ICS 87.040 Supersedes EN ISO 7783-1:1999, EN ISO 7783-2:1999
English Version
Paints and varnishes - Determination of water-vapour
transmission properties - Cup method (ISO 7783:2011)
Peintures et vernis - Détermination des propriétés de Beschichtungsstoffe - Bestimmung der
transmission de la vapeur d'eau - Méthode de la coupelle Wasserdampfdurchlässigkeit - Schalenverfahren (ISO
(ISO 7783:2011) 7783:2011)
This European Standard was approved by CEN on 21 November 2011.

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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7783:2011: E
worldwide for CEN national Members.

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SIST EN ISO 7783:2012
EN ISO 7783:2011 (E)
Contents Page
Foreword .3

2

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SIST EN ISO 7783:2012
EN ISO 7783:2011 (E)
Foreword
This document (EN ISO 7783:2011) 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 May 2012, and conflicting national standards shall be withdrawn at the
latest by May 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 7783-1:1999, EN ISO 7783-2:1999.
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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 7783:2011 has been approved by CEN as a EN ISO 7783:2011 without any modification.

3

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SIST EN ISO 7783:2012

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SIST EN ISO 7783:2012
INTERNATIONAL ISO
STANDARD 7783
First edition
2011-11-01
Paints and varnishes — Determination of
water-vapour transmission properties —
Cup method
Peintures et vernis — Détermination des propriétés de transmission de
la vapeur d’eau — Méthode de la coupelle
Reference number
ISO 7783:2011(E)
©
ISO 2011

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SIST EN ISO 7783:2012
ISO 7783:2011(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved

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SIST EN ISO 7783:2012
ISO 7783:2011(E)
Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus and materials . 3
5.1 Substrate for non-self-supporting coatings . 3
5.2 Test cup . 3
5.3 Ammonium dihydrogen phosphate (NH H PO ) solution for wet-cup method . 3
4 2 4
5.4 Desiccant for dry-cup method . 3
5.5 Sealing material . 4
5.6 Test enclosure . 4
5.7 Balance . 4
6 Preparation for the test . 4
6.1 Sampling of coating material . 4
6.2 Preparation of test pieces . 4
6.3 Determination of the thickness of the coating . 5
6.4 Preparation of the test assemblies . 6
7 Procedure . 6
8 Expression of results . 7
8.1 Water-vapour transmission rate, �, of self-supporting coatings . 7
8.2 Water-vapour transmission rate, �, of non-self-supporting coatings . 7
8.3 Water-vapour diffusion-equivalent air layer thickness, � . 9
d
8.4 Water-vapour resistance factor, � . 9
9 Precision .10
9.1 Repeatability, (� .) .10
9.2 Reproducibility, (� ).10
10 Test report .10
Annex A (informative) Derivation of Equation (8) in Subclause 8.3 for the calculation of the water-
vapour diffusion-equivalent air layer thickness, � .12
d
Annex B (normative) Use of molten wax for sealing the test assembly .14
Bibliography .18
© ISO 2011 – All rights reserved iii

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SIST EN ISO 7783:2012
ISO 7783:2011(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7783 was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 9,
General test methods for paints and varnishes.
This first edition of ISO 7783 cancels and replaces ISO 7783-1:1996 and ISO 7783-2:1999, which have been
merged and technically revised. It also incorporates the Technical Corrigendum ISO 7783-1:1996/Cor.1:1998.
iv © ISO 2011 – All rights reserved

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SIST EN ISO 7783:2012
ISO 7783:2011(E)
Introduction
ISO 7783 is one of a series of standards dealing with the sampling and testing of paints, varnishes and related
products. It describes a method for determining the water-vapour transmission rate of self-supporting and non-
self-supporting coatings.
The water-vapour transmission rate is not necessarily a linear function of film thickness, temperature or relative-
humidity difference. A determination carried out under one set of conditions will not necessarily be comparable
with one carried out under other conditions. Therefore, it is essential that the conditions of test are chosen to
be as close as possible to the conditions of use.
Water-vapour transmission is of greatest interest under conditions of high humidity. For this reason, the wet-
cup method has been adopted as the reference method. By agreement, other procedures and conditions, like
the dry-cup method, may be used.
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SIST EN ISO 7783:2012

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SIST EN ISO 7783:2012
INTERNATIONAL STANDARD ISO 7783:2011(E)
Paints and varnishes — Determination of water-vapour
transmission properties — Cup method
1 Scope
This International Standard specifies a method for determining the water-vapour transmission properties of
coatings of paints, varnishes and related products.
It supplements ISO 12572. As far as possible, the procedure, the definitions and the calculations have been
taken over from ISO 12572. It is recommended that ISO 12572 be consulted, if necessary, to obtain a better
understanding of the procedure specified in this International Standard.
2
Water-vapour transmission rates of more than 680 g/(m�d) (i.e. water-vapour diffusion-equivalent air layer
thicknesses, �, of less than 0,03 m) will not be accurately quantified by the test method described in this
d
International Standard.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 1513, Paints and varnishes — Examination and preparation of test samples
ISO 2808, Paints and varnishes — Determination of film thickness
ISO 3233, Paints and varnishes — Determination of percentage volume of non-volatile matter by measuring
the density of a dried coating
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
water-vapour transmission rate
�
mass of water vapour that is transmitted over a given period through a given surface area of a test piece under
specified constant conditions of relative humidity at each face of the test piece
2
NOTE 1 It is measured in grams per square metre per day [g/(m�d)].
NOTE 2 A water-vapour transmission rate measured at atmospheric pressure, �, can be converted to the equivalent
value at standard atmospheric pressure, �, by multiplying by �/�. This allows a linear correlation with the water-vapour
0 0
diffusion-equivalent air layer thickness (�) value (see 3.3) by the factor 20,4.
d
NOTE 3 The term “water-vapour transmission” is often incorrectly used for water-vapour transmission rate.
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SIST EN ISO 7783:2012
ISO 7783:2011(E)
3.2
rate of flow of water vapour through the test piece
�
mass of water vapour that is transmitted over a given period through a test piece under specified constant
conditions of relative humidity at each face of the test piece
NOTE It is measured in grams per hour.
3.3
water-vapour diffusion-equivalent air layer thickness
�
d
thickness of a static air layer that has, under the same conditions of measurement, the same water-vapour
transmission rate as the coating tested
NOTE It is measured in metres.
3.4
water-vapour resistance factor
�
factor that indicates how many times greater the water-vapour resistance of a material is compared with a layer
of static air of the same thickness at the same temperature and pressure
NOTE 1 It is dimensionless.
NOTE 2 The calculation and use of a water-vapour resistance factor is meaningful only if the water-vapour transmission
rate of a particular material is a constant, i.e. independent of the thickness, which, however, is normally not the case for
coatings.
3.5
test piece
�non-self-supporting coatings� supporting substrate with the coating applied to it or �self-supporting coatings�
the coating alone
3.6
wet-cup method
method of measuring water-vapour permeability in which the test piece is sealed to the rim of a cup containing
a saturated aqueous solution of ammonium dihydrogen phosphate
NOTE This is the most convenient manner of carrying out determinations of water-vapour permeability under
conditions of high relative humidity (between 93 % and 50 %).
3.7
dry-cup method
method of measuring water-vapour permeability in which the test piece is sealed to the rim of a cup containing
a desiccant
NOTE This is the most convenient manner of carrying out determinations of water-vapour permeability under
conditions of low relative humidity (between 50 % and 3 %).
3.8
test assembly
assembly consisting of a test piece sealed to the rim of a test cup containing saturated ammonium dihydrogen
phosphate solution in contact with undissolved ammonium dihydrogen phosphate crystals (wet-cup method) or
containing desiccant (dry-cup method)
3.9
test area
area of the face of the test piece through which the water vapour flows during the test
NOTE It is measured in square metres.
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SIST EN ISO 7783:2012
ISO 7783:2011(E)
4 Principle
A test assembly consisting of a self-supporting coating, or a non-self-supporting coating on porous substrate,
sealed to the rim of a cup is placed in a test enclosure kept at a specified temperature (e.g. 23 °C) and relative
humidity (e.g. 50 %). The relative humidity in the cup is maintained at a constant level — either at 93 % by
means of a saturated salt solution (wet-cup method) or at 3 % by means of a desiccant (dry-cup method).
Because of the difference between the partial pressure of the water vapour inside the test cup and the partial
pressure of the water vapour in the test enclosure, water vapour diffuses through the coating under test. By
weighing the test assembly at suitable time intervals, the change in mass of the test assembly is followed.
From the change in mass and the test area, the water-vapour transmission rate and the water-vapour diffusion-
equivalent air layer thickness are calculated.
5 Apparatus and materials
5.1 Substrate for non-self-supporting coatings
2
Any homogenous, porous material which has a water-vapour transmission rate above 240 g/(m�d) is suitable
for use as the substrate for non-self-supporting coatings, for instance polyethylene frits, cellular-concrete discs,
glass frits, unglazed ceramic tiles.
When using cellular-concrete substrates, the coating shall be applied on the smooth side.
If the coating system under test does not include a primer and it is necessary to use one before applying the
coating system under test, do so, but the transmission rate of the primed substrate will have to be determined
separately.
5.2 Test cup
Test cups are made of glass, plastic or metal. The test cup used shall be resistant to corrosion under the
conditions of the test.
NOTE For aluminium test cups, a wall thickness of 1 mm has been found to be satisfactory.
The exact surface area of the test piece exposed is defined by the design of the cup. The area of the exposed
2 2
surface shall be at least 50 cm for non-self-supporting coatings and at least 10 cm for self-supporting coatings.
The cup shall be so designed that an efficient seal is made between it and the test piece, using sealing material
(see 5.5), if necessary.
When the saturated solution (5.3) or desiccant (5.4) has been placed in the cup, the area of the surface of the
saturated solution or desiccant shall be similar to that of the exposed surface of the test piece. The air gap
between the test piece and the surface of the solution or desiccant shall be between 10 mm and 30 mm.
5.3 Ammonium dihydrogen phosphate (NH H PO ) solution for wet-cup method
4 2 4
Prepare a saturated solution of ammonium dihydrogen phosphate (analytical grade) in contact with undissolved
crystals, using water of at least grade 3 purity as defined in ISO 3696.
In the wet-cup method, which is the reference method, the relative humidity in a cup containing this saturated
solution will be 93 %. The resulting water vapour pressure difference relative to the test enclosure, in which the
relative humidity is maintained at 50 %, is 1 207 Pa at standard temperature (23 °C) and pressure (101 325 Pa).
5.4 Desiccant for dry-cup method
The desiccant shall be either dried silica gel in the form of granules passing a 4 mm sieve but retained on a
1,6 mm sieve, or anhydrous calcium chloride which has been dried at 200 °C.
It shall be possible to complete the test before the efficiency of the desiccant is reduced appreciably.
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SIST EN ISO 7783:2012
ISO 7783:2011(E)
In the dry-cup method, the relative humidity in the cup shall be 3 %. The resulting water-vapour pressure
difference relative to the test enclosure, in which the relative humidity is maintained at 50 %, is 1 400 Pa at
standard temperature (23 °C) and pressure (101 325 Pa).
5.5 Sealing material
It shall be ensured that the test assembly is fully sealed, with the exception of the test area. The sealing
material shall be impermeable and free from cracks. For sealing, mechanical clamps, wax or two-component
sealing materials have been found suitable. The use of molten wax for sealing the test assembly is described
in Annex B.
The sealing material shall not contain solvents or other volatile constituents which could cause any change in
the coating or lead to weighing errors caused by the evaporation of solvent.
NOTE The most usual way of sealing the cup is to fit the cup with a mechanical clamp or screw device which can
incorporate a sealing ring made of a suitable polymeric material. Mechanical sealing might not be suitable if the test piece
has a rough surface or if it is very fragile. In such cases, the use of molten wax is more satisfactory.
5.6 Test enclosure
The test enclosure shall be of a design such that both the temperature and the relative humidity in the enclosure
can be controlled at the levels required for the test. Thus, for the reference method, the enclosure shall be
capable of maintaining the temperature at (23 � 2) °C and the relative humidity at (50 � 5) % (standard conditions
as defined in ISO 3270). To ensure uniform conditions during the test, the air shall be caused to flow over the
outer surface of the test piece at a speed between 0,02 m/s and 0,3 m/s. The ambient air pressure shall be
corrected to standard pressure (1 013,25 hPa) as described in 8.1.
NOTE Maintaining the air speed at the correct level is the second most important source of error after preparation of
the test pieces.
When cups have to be removed from the test enclosure for weighing, the specified conditions shall be re-
established not more than 15 min after the door of the enclosure has been closed. The door shall remain open
for the shortest possible time. This is especially important with materials having a high permeability.
5.7 Balance
The balance used shall be suitable for determining the change in mass of the test assembly with an accuracy
2
of 1 mg or better for cups giving a test area of 50 cm or less, or 10 mg for cups giving a test area greater than
2
50 cm .
The most suitable arrangement is to have the balance located in the test enclosure. If this is not possible, care
shall be taken that no loss in mass occurs during the transport of the test assembly to the balance.
6 Preparation for the test
6.1 Sampling of coating material
Take a representative sample of the product to be tested (or of each product in the case of a multi-coat system),
as described in ISO 15528.
Examine and prepare each sample for testing, as described in ISO 1513.
6.2 Preparation of test pieces
6.2.1 Preparation of non-self-supporting coatings on a porous substrate
The substrate shall be clean and dry.
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SIST EN ISO 7783:2012
ISO 7783:2011(E)
Apply the coating material to be tested to the substrate in accordance with the manufacturer’s application
instructions. Do not apply less than the amount indicated by the manufacturer and not more than 50 % more,
e.g. by applying a larger number of coats or by applying the first coat as a primer coat after dilution. It is
essential that the coating be complete, continuous, homogeneous and free from visible imperfections. If the
amount necessary to produce such a coating is more than 50 % greater than the amount indicated by the
manufacturer, use another substrate or another test method.
Dry the test pieces for 7 days in freely circulating air at (23 � 2) °C and (50 � 5) % relative humidity.
6.2.2 Preparation of self-supporting coatings
Use a substrate from which the coating can be easily detached when dry/hard. The most suitable substrates
are glass plates coated with high-density polyethylene or polytetrafluoroethylene which is free from surface
defects. Other techniques may be used, for example precoating a substrate with a soluble material such as
poly(vinyl alcohol) which will permit the coating to be removed easily by soaking in water. This method should
be used with caution, however, since water-soluble material can affect the water-vapour permeability of the
coating.
Coat the substrate by the method specified by the manufacturer and dry it for 7 days in freely circulating air
at (23 � 2) °C and (50 � 5) % relative humidity (if stoving is required, care shall be taken to ensure that the
substrate chosen is not affected at the relevant temperature).
Remove the coating carefully from the substrate.
Use a cutting template (see Figure B.1) to cut out specimens of a size suitable for the cup. Examine the test
pieces visually and discard any which appear to have pinholes.
6.2.3 Conditioning
Method A
For coatings which, in use, will not be exposed to rain, e.g. coatings for interior use or for arid places, condition
the test pieces at (23 � 2) °C and (50 � 5) % relative humidity for 28 days or until the difference in mass between
two consecutive weighings, carried out at 24 h intervals, is less than 1 %.
Method B
Since, in use, the volatile and/or water-soluble constituents of a coating can be removed by the influence of the
weather (in particular, water-soluble constituents can be leached out by rainwater), coatings which are affected
by rain shall be conditioned prior to the determination of the water-vapour transmission rate by subjecting the
test pieces to 3 cycles under the following conditions:
— 24 h in water (tap water) at (23 � 2) °C;
— 24 h drying at (50 � 2) °C.
During the weekend or any interruption of the conditioning for other reasons, store the test pieces at (23 � 2) °C
and (50 � 5) % relative humidity.
After the last cycle, continue to dry the test pieces at (50 � 2) °C for at least another 24 h. Then condition the
test pieces at (23 � 2) °C and (50 � 5) % relative humidity for at least 24 h before carrying out the test.
6.3 Determination of the thickness of the coating
6.3.1 General
The thickness, �, of the coating is required for the calculation of the water-vapour resistance factor, �. It may
be determined by calculation or by optical, mechanical or other suitable methods.
NOTE Optical determination of the thickness of the coating can also be used to check the test piece for pores, holes,
etc., and to determine the depth of penetration of the coating material into the substrate.
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SIST EN ISO 7783:2012
ISO 7783:2011(E)
6.3.2 Determination of the thickness of the coating by calculation
Calculate the dry-film thickness, �, in micrometres, from the application rate (the amount of coating material
applied), using the following equation:
C×NV
V
d = (1)
100
where
� is the application rate, in millilitres per square metre;
NV is the non-volatile-matter content, expressed as a percentage by volume, determined in
V
accordance with ISO 3233.
6.3.3 Determination of the thickness of the coating by optical, mechanica
...