Paints and varnishes - Determination of water-vapour transmission properties - Cup method (ISO 7783:2018)

This document 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. ISO 12572 can be consulted, if necessary, to obtain a better understanding of the procedure specified in this document.
Water-vapour transmission rates of more than 680 g/(m2⋅d) (i.e. water-vapour diffusion-equivalent air layer thicknesses, sd, of less than 0,03 m) are not accurately quantified by the test method described in this document.

Beschichtungsstoffe - Bestimmung der Wasserdampfdurchlässigkeit - Schalenverfahren (ISO 7783:2018)

Dieses Dokument legt ein Verfahren zum Bestimmen der Wasserdampfdurchlässigkeit von Beschichtungs-stoffen und ähnlichen Produkten fest.
Die Norm ergänzt ISO 12572. Soweit möglich, wurden das Verfahren, die Definitionen und die Berechnungen aus ISO 12572 übernommen. ISO 12572 kann bei Bedarf herangezogen werden, um das in dieser Norm spezifizierte Verfahren besser zu verstehen.
Eine Wasserdampf-Diffusionsstromdichte V von mehr als 680 g/(m2 ⋅ d) (d. h. eine wasserdampfdiffusions-äquivalente Luftschichtdicke sd unter 0,03 m) wird nach dem in diesem Dokument beschriebenen Prüf-verfahren nicht genau bestimmt

Peintures et vernis - Détermination des propriétés de transmission de la vapeur d'eau - Méthode de la coupelle (ISO 7783:2018)

Le présent document spécifie une méthode permettant de déterminer les propriétés de transmission de la vapeur d'eau des revêtements de peinture, vernis et produits assimilés.
Il complète l'ISO 12572. Le mode opératoire, les définitions et les calculs ont, dans la mesure du possible, été repris de l'ISO 12572. L'ISO 12572 peut être consultée, si nécessaire, pour mieux appréhender le mode opératoire spécifié dans le présent document.
Des coefficients de transmission de la vapeur d'eau supérieurs à 680 g/(m2⋅j) (c'est-à-dire des épaisseurs d'air équivalentes pour la diffusion de vapeur d'eau, sd, inférieures à 0,03 m) ne sont pas déterminés quantitativement avec exactitude par la méthode d'essai décrite dans le présent document.

Barve in laki - Ugotavljanje prepustnosti vodne pare - Metoda s čašo (ISO 7783:2018)

Ta dokument določa metodo za ugotavljanje prepustnosti vodne pare barvnih in lakirnih prevlek ter sorodnih premazov.
Dopolnjuje standard ISO 12572. Postopek, opredelitve in izračuni so bili v kar največji možni meri vzeti iz standarda ISO 12572. Če je potrebno, je standard ISO 12572 mogoče uporabiti za boljše razumevanje postopka iz tega dokumenta.
Hitrosti prepustnosti vodne pare, večje od 680 g/(m2⋅d) (tj. debeline zračnega sloja z ekvivalentno difuzijo vodne pare, sd, manjše od 0,03 m), niso natančno kvantificirane s preskusno metodo, ki je opisana v tem dokumentu.

General Information

Status
Published
Publication Date
06-Nov-2018
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
07-Nov-2018
Completion Date
07-Nov-2018

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Paints and varnishes - Determination of water-vapour transmission properties - Cup

method (ISO 7783:2018)

Beschichtungsstoffe - Bestimmung der Wasserdampfdurchlässigkeit - Schalenverfahren

(ISO 7783:2018)

Peintures et vernis - Détermination des propriétés de transmission de la vapeur d'eau -

Méthode de la coupelle (ISO 7783:2018)
Ta slovenski standard je istoveten z: EN ISO 7783:2018
ICS:
87.040 Barve in laki Paints and varnishes
SIST EN ISO 7783:2018 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 7783:2018
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SIST EN ISO 7783:2018
EN ISO 7783
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2018
EUROPÄISCHE NORM
ICS 87.040 Supersedes EN ISO 7783:2011
English Version
Paints and varnishes - Determination of water-vapour
transmission properties - Cup method (ISO 7783:2018)

Peintures et vernis - Détermination des propriétés de Beschichtungsstoffe - Bestimmung der

transmission de la vapeur d'eau - Méthode de la Wasserdampfdurchlässigkeit - Schalenverfahren (ISO

coupelle (ISO 7783:2018) 7783:2018)
This European Standard was approved by CEN on 22 September 2018.

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, 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 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

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7783:2018 E

worldwide for CEN national Members.
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SIST EN ISO 7783:2018
EN ISO 7783:2018 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 7783:2018
EN ISO 7783:2018 (E)
European foreword

This document (EN ISO 7783:2018) 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 2019, and conflicting national standards shall be

withdrawn at the latest by May 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 7783:2011.

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 7783:2018 has been approved by CEN as EN ISO 7783:2018 without any modification.

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SIST EN ISO 7783:2018
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SIST EN ISO 7783:2018
INTERNATIONAL ISO
STANDARD 7783
Second edition
2018-10
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 7783:2018(E)
ISO 2018
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SIST EN ISO 7783:2018
ISO 7783:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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SIST EN ISO 7783:2018
ISO 7783:2018(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 ........................... 4

4 2 4

5.4 Desiccant for dry-cup method ................................................................................................................................................... 4

5.5 Sealing material ...................................................................................................................................................................................... 4

5.6 Test enclosure .......................................................................................................................................................................................... 4

5.7 Balance ........................................................................................................................................................................................................... 4

6 Preparation for the test ................................................................................................................................................................................. 5

6.1 Sampling of coating material ...................................................................................................................................................... 5

6.2 Preparation of test pieces .............................................................................................................................................................. 5

6.2.1 Preparation of non-self-supporting coatings on a porous substrate .................................. 5

6.2.2 Preparation of self-supporting coatings ...................................................................................................... 5

6.2.3 Conditioning ........................................................................................................................................................................ 5

6.3 Determination of the thickness of the coating............................................................................................................. 6

6.3.1 General...................................................................................................................................................................................... 6

6.3.2 Determination of the thickness of the coating by calculation .................................................. 6

6.3.3 Determination of the thickness of the coating by optical, mechanical or

other suitable methods .............................................................................................................................................. 6

6.4 Preparation of the test assemblies ......................................................................................................................................... 6

7 Procedure..................................................................................................................................................................................................................... 7

8 Expression of results ........................................................................................................................................................................................ 7

8.1 Water-vapour transmission rate, V, of self-supporting coatings ................................................................. 7

8.1.1 Rate of flow of water vapour, G, through the test piece .................................................................. 7

8.1.2 Water-vapour transmission rate, V, of the coating ............................................................................. 7

8.2 Water-vapour transmission rate, V, of non-self-supporting coatings ..................................................... 8

8.2.1 General...................................................................................................................................................................................... 8

8.2.2 Rate of flow of water vapour through the substrate, G , and through the

substrate plus coating, G ...................................................................................................................................... 8

8.2.3 Water-vapour transmission rate, V , of the substrate ...................................................................... 8

8.2.4 Water-vapour transmission rate, V , of the substrate plus coating.................................... 9

8.2.5 Water-vapour transmission rate, V, of the coating ............................................................................. 9

8.3 Water-vapour diffusion-equivalent air layer thickness, s .............................................................................. 9

8.4 Water-vapour resistance factor, μ ......................................................................................................................................10

9 Precision ....................................................................................................................................................................................................................10

9.1 Repeatability, (r) .................................................................................................................................................................................10

9.2 Reproducibility, (R) .........................................................................................................................................................................10

10 Test report ................................................................................................................................................................................................................11

Annex A (informative) Derivation of Formula (8) for the calculation of the water-vapour

diffusion-equivalent air layer thickness, s ...........................................................................................................................12

Annex B (normative) Use of molten wax for sealing the test assembly ........................................................................14

Bibliography .............................................................................................................................................................................................................................18

© ISO 2018 – All rights reserved iii
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SIST EN ISO 7783:2018
ISO 7783:2018(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 methods for paints and varnishes.

This second edition cancels and replaces the first edition (ISO 7783:2011), of which it constitutes a

minor revision to correct the conversion factor in Formula (3) and to add a reference to ISO 4618 on

paints and varnishes terminology in Clause 3.

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 2018 – All rights reserved
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SIST EN ISO 7783:2018
ISO 7783:2018(E)
Introduction

This document 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.
© ISO 2018 – All rights reserved v
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SIST EN ISO 7783:2018
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SIST EN ISO 7783:2018
INTERNATIONAL STANDARD ISO 7783:2018(E)
Paints and varnishes — Determination of water-vapour
transmission properties — Cup method
1 Scope

This document 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. ISO 12572 can be consulted, if necessary, to obtain a better

understanding of the procedure specified in this document.

Water-vapour transmission rates of more than 680 g/(m ⋅d) (i.e. water-vapour diffusion-equivalent air

layer thicknesses, s , of less than 0,03 m) are not accurately quantified by the test method described 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 1513, Paints and varnishes — Examination and preparation of test samples
ISO 2808, Paints and varnishes — Determination of film thickness

ISO 3233-1, Paints and varnishes — Determination of the percentage volume of non-volatile matter —

Part 1: Method using a coated test panel to determine non-volatile matter and to determine dry film density

by the Archimedes principle
ISO 3696, Water for analytical laboratory use — Specification and test methods
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:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
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

Note 1 to entry: It is measured in grams per square metre per day [g/(m ⋅d)].
© ISO 2018 – All rights reserved 1
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SIST EN ISO 7783:2018
ISO 7783:2018(E)

Note 2 to entry: A water-vapour transmission rate measured at atmospheric pressure, p, can be converted to the

equivalent value at standard atmospheric pressure, p , by multiplying by p/p . This allows a linear correlation

0 0

with the water-vapour diffusion-equivalent air layer thickness (s ) value (see 3.3) by the factor 20,4.

Note 3 to entry: The term “water-vapour transmission” is often incorrectly used for water-vapour

transmission rate.
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 1 to entry: It is measured in grams per hour.
3.3
water-vapour diffusion-equivalent air layer thickness

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 1 to entry: 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 to entry: It is dimensionless.

Note 2 to entry: 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

supporting substrate with the coating applied to it

3.6
test piece
coating alone
3.7
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 1 to entry: This is the most convenient manner of carrying out determinations of water-vapour permeability

under conditions of high relative humidity (between 93 % and 50 %).
3.8
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 1 to entry: This is the most convenient manner of carrying out determinations of water-vapour permeability

under conditions of low relative humidity (between 50 % and 3 %).
2 © ISO 2018 – All rights reserved
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SIST EN ISO 7783:2018
ISO 7783:2018(E)
3.9
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)
3.10
test area

area of the face of the test piece through which the water vapour flows during the test

Note 1 to entry: It is measured in square metres.
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

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

2 2

exposed 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.
© ISO 2018 – All rights reserved 3
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SIST EN ISO 7783:2018
ISO 7783:2018(E)
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.

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 (101 325 Pa) 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 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 50 cm .

The most suitable arrangement is to have the balance located in the test enclosure. If thi

...

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