SIST EN ISO 535:2023

Paper and board - Determination of water absorptiveness - Cobb method (ISO 535:2023)

This document specifies a method for determining the water absorptiveness of paper and board, including corrugated fibreboard, under standard conditions.
This document is not applicable for paper of grammage less than 50 g/m2 or embossed paper. It is not applicable for porous papers such as newsprint or papers such as blotting paper or other papers having a relatively high-water absorptiveness for which ISO 8787 is more suitable.

Papier und Pappe - Bestimmung des Wasserabsorptionsvermögens - Cobb-Verfahren (ISO 535:2023)

Dieses Dokument legt ein Verfahren zur Bestimmung des Wasserabsorptionsvermögens von Papier und Pappe, einschließlich Wellpappe, unter Standardbedingungen fest.
Dieses Dokument ist nicht anwendbar auf Papier mit einer flächenbezogenen Masse von weniger als 50 g/m2 oder für geprägtes Papier. Es ist nicht anwendbar für poröses Papier wie Zeitungsdruckpapier oder Papiere wie Löschpapier oder andere Papiere mit einem relativ hohen Wasserabsorptionsvermögen. Hierfür ist ISO 8787 besser geeignet.

Papier et carton - Détermination de la capacité d'absorption d'eau - Méthode de Cobb (ISO 535:2023)

Le présent document spécifie une méthode de détermination de la capacité d’absorption d’eau du papier et du carton, y compris du carton ondulé, dans des conditions normalisées.
Le présent document ne s’applique pas aux types de papiers suivants: papier de grammage inférieur à 50 g/m2, papier gaufré, papiers poreux tels que le papier journal, papiers tels que le papier buvard ou d’autres papiers ayant une capacité d’absorption d’eau relativement élevée, l’ISO 8787 étant mieux adaptée dans ces cas.

Papir, karton in lepenka - Določevanje absorpcije vode - Cobbova metoda (ISO 535:2023)

Ta dokument navaja metodo za določevanje absorpcije vode pri papirju, kartonu in lepenki, vključno z valovitim kartonom, v standardnih pogojih.
Ta dokument se ne uporablja za papir z gramaturo, ki je nižja od 50 g/m2, ali za reliefno pretisnjen papir. Ne uporablja se za porozni papir, kot je časopisni papir ali papir, npr. pivnik ali drugi papirji z relativno visoko absorpcijo vode, za katere je bolj primeren standard ISO 8787.

General Information

• Status: Published
• Public Enquiry End Date: 24-Mar-2022
• Publication Date: 12-Sep-2023
• ICS: 85.060 - Paper and board
• Technical Committee: VPK - Pulp, paper, board and products
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 20-Jun-2023
• Due Date: 25-Aug-2023
• Completion Date: 13-Sep-2023
• Ref Project: EN ISO 535:2023 - Paper and board - Determination of water absorptiveness - Cobb method (ISO 535:2023)

Relations

• Replaces: SIST EN ISO 535:2014 - Paper and board - Determination of water absorptiveness - Cobb method (ISO 535:2014)
• Effective Date: 01-Sep-2023

Overview

EN ISO 535:2023 (ISO 535:2023) specifies the Cobb method for determining the water absorptiveness of paper and board - including corrugated fibreboard - under standard laboratory conditions. The method measures the mass of water absorbed by a defined test area and expresses the result as a Cobb value (grams per square metre, g/m²). This edition, adopted by CEN in 2023, supersedes EN ISO 535:2014.

Key topics and technical requirements

• Scope and exclusions
  • Applicable to paper and board (not for papers with grammage < 50 g/m² or embossed paper).
  • Not suitable for highly porous papers (e.g., newsprint, blotting paper); for these ISO 8787 is recommended.
• Principle
  • Weigh test piece before and after exposing one surface to water for a specified time, blot, and calculate absorbed mass per unit area.
  • Typical test area is 100 cm² (cylinder internal diameter 112.8 mm).
• Reagents and conditioning
  • Use distilled/deionized water complying with ISO 14487 at laboratory conditioning temperatures (23 °C ±1 °C or 27 °C ±1 °C in tropical climates).
  • Condition samples per ISO 187; sampling per ISO 186.
• Apparatus and materials
  • Absorptiveness tester with rigid base and metal cylinder (to ensure uniform contact and containment of 10 mm water depth).
  • Metal roller (≈200 mm wide, mass ~10 kg) for blotting; balance readable to 1 mg; timer; blotting paper ~250 g/m² ±25 g/m² (see ISO 5269‑1).
• Procedure and reporting
  • Prepare multiple test pieces per face, avoid contamination of test area, mount securely, expose, blot, reweigh.
  • Results expressed in g/m²; Clause 12 (precision) and Clause 13 (test report) set requirements for reproducibility and documentation.

Applications and who uses it

• Quality control: routine checks in paper mills and converting plants to monitor water absorptiveness and batch consistency.
• Product development: evaluating coatings, sizing treatments, and surface finishes that affect water uptake.
• Packaging industry: assessing corrugated fibreboard and board performance for moisture resistance and handling.
• Printing and converting: predicting runnability, drying behavior and adhesive performance where surface water interaction is critical.
• Typical users: papermakers, packaging engineers, laboratory technicians, quality managers, suppliers specifying material performance.

Related standards

• ISO 186 - Sampling for average quality
• ISO 187 - Standard atmosphere for conditioning and testing
• ISO 14487 - Standard water for physical testing
• ISO 8787 - Water absorptiveness for highly absorbent/porous papers
• ISO 5269‑1 - Blotting papers (suitable types referenced)

Keywords: EN ISO 535:2023, ISO 535:2023, Cobb method, water absorptiveness, paper and board testing, Cobb value, CEN, laboratory conditioning, corrugated fibreboard.

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2023
Nadomešča:
SIST EN ISO 535:2014
Papir, karton in lepenka - Določevanje absorpcije vode - Cobbova metoda (ISO
535:2023)
Paper and board - Determination of water absorptiveness - Cobb method (ISO 535:2023)
Papier und Pappe - Bestimmung des Wasserabsorptionsvermögens - Cobb-Verfahren
(ISO 535:2023)
Papier et carton - Détermination de la capacité d'absorption d'eau - Méthode de Cobb
(ISO 535:2023)
Ta slovenski standard je istoveten z: EN ISO 535:2023
ICS:
85.060 Papir, karton in lepenka Paper and board
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 535
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2023
EUROPÄISCHE NORM
ICS 85.060 Supersedes EN ISO 535:2014
English Version
Paper and board - Determination of water absorptiveness -
Cobb method (ISO 535:2023)
Papier et carton - Détermination de la capacité Papier und Pappe - Bestimmung des
d'absorption d'eau - Méthode de Cobb (ISO 535:2023) Wasserabsorptionsvermögens - Cobb-Verfahren (ISO
535:2023)
This European Standard was approved by CEN on 13 February 2023.

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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 535:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 535:2023) 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 October 2023, and conflicting national standards shall
be withdrawn at the latest by October 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 535:2014.
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 535:2023 has been approved by CEN as EN ISO 535:2023 without any modification.

INTERNATIONAL ISO
STANDARD 535
Fourth edition
2023-03
Paper and board — Determination of
water absorptiveness — Cobb method
Papier et carton — Détermination de la capacité d'absorption d'eau
— Méthode de Cobb
Reference number
ISO 535:2023(E)
ISO 535:2023(E)
© ISO 2023
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 535:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 2
6 Apparatus . 2
7 Sampling . 3
8 Conditioning . 3
9 Preparation of test pieces .3
10 Procedure .3
10.1 General . 3
10.2 Mounting of the test pieces . . 3
10.3 Exposure to water and blotting . 3
10.4 Times of test . 5
10.5 Rejection of test pieces . 5
11 Expression of results . 5
12 Precision . 6
13 Test report . 6
Annex A (informative) Precision . 7
Annex B (informative) Suitable blotting paper . 9
Bibliography .10
iii
ISO 535:2023(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 fourth edition cancels and replaces the third edition (ISO 535:2014), which has been technically
revised.
The main changes are as follows:
— requirements in 5.1 and 5.2 added;
— Clause 6 and 6.2 revised;
— preparation of test pieces added in Clause 9;
— Subclauses 10.3 and 10.4 revised and requirements added;
— several additional explanations added in 10.5.
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
INTERNATIONAL STANDARD ISO 535:2023(E)
Paper and board — Determination of water absorptiveness
— Cobb method
1 Scope
This document specifies a method for determining the water absorptiveness of paper and board,
including corrugated fibreboard, under standard conditions.
This document is not applicable for paper of grammage less than 50 g/m or embossed paper. It is not
applicable for porous papers such as newsprint or papers such as blotting paper or other papers having
a relatively high-water absorptiveness for which ISO 8787 is more suitable.
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 14487, Pulps — Standard water for physical testing
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/
3.1
water absorptiveness
Cobb value
calculated mass of water absorbed in a specified time by 1 m of paper or board under specified
conditions
Note 1 to entry: The test area is normally 100 cm .
4 Principle
A test piece is weighed immediately before and after exposure for a specified time of one surface to
water, followed by blotting. The result of the increase in mass is expressed in grams per square
metre (g/m ).
The test piece shall not show any sign of penetration through or leakage outside the test ring (see 10.5).
ISO 535:2023(E)
5 Reagents and materials
5.1 Water, distilled or deionized, at the laboratory conditioning temperature, i.e. 23 °C ± 1 °C or
27 °C ± 1 °C in tropical countries. The water shall fulfil the requirements of ISO 14487.
2 2
5.2 Blotting paper, having a grammage of 250 g/m ± 25 g/m .
The blotting paper shall have dimensions of at least 140 mm × 140 mm either circular or rectangular.
Blotting papers in accordance with ISO 5269-1 are suitable, see Annex B.
6 Apparatus
6.1 Absorptiveness tester for the determination of water absorptiveness.
Any type of apparatus may be used which permits
— an immediate and uniform contact of the water with the part of the test piece submitted to the test,
— controlled rapid removal of the unabsorbed water from the test piece at the end of the contact
period, and
— the rapid removal of the test piece without the risk of water contacting the test piece outside the test
area.
In its simplest form, the apparatus consists of a rigid base with a smooth, planar surface, and a rigid
metal cylinder of 112,8 mm ± 0,2 mm internal diameter (corresponding to a test area of 100 cm ) and
with a means of clamping it firmly to the base plate. The edge o
...