ISO 13821:2020

Corrugated fibreboard - Determination of edgewise crush resistance - Waxed edge method

This document specifies a method for the determination of the edgewise crush resistance of corrugated fibreboard. The force is applied in the direction of the flute axis. This method is applicable to single-wall (double-faced), double-wall, and triple-wall corrugated fibreboard. It may also be used to test samples taken from corrugated cases and other converted products. While the method is applicable to waxed corrugated fibreboard, care must be taken that the heat used in the waxing step does not affect the corrugated structure. This is controlled by observing that failure during the test still occurs away from the loaded edges.

Carton ondulé — Détermination de la résistance à la compression sur chant — Méthode du bord paraffiné

General Information

• Status: Published
• Publication Date: 24-Jun-2020
• ICS: 85.060 - Paper and board
• Technical Committee: ISO/TC 6/SC 2 - Test methods and quality specifications for paper and board
• Drafting Committee: ISO/TC 6/SC 2 - Test methods and quality specifications for paper and board
• Current Stage: 9093 - International Standard confirmed
• Start Date: 04-Sep-2025
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 13821:2002 - Corrugated fibreboard - Determination of edgewise crush resistance - Waxed edge method
• Effective Date: 23-Apr-2020

Overview

ISO 13821:2020 specifies a standardized test method for determining the edgewise crush resistance (ECT) of corrugated fibreboard using the waxed edge technique. This method measures the compressive strength of corrugated boards by applying force along the flute axis until structural failure occurs. It applies to single-wall, double-wall, and triple-wall corrugated fibreboard, as well as samples taken from converted packaging products such as corrugated shipping cases. The waxed edge method helps eliminate edge effects that can influence test results, providing reliable ECT values that correlate well with the compression strength of finished transport packages.

Key Topics

• Test Scope: The method is valid for various corrugated fibreboard types including single-wall (double-faced), double-wall, and triple-wall configurations. Applicable to both raw boards and finished packaging products.

• Test Principle: A rectangular specimen with flutes oriented perpendicularly to the compression platens is subjected to a compressive force until failure. The loading edges are reinforced with paraffin wax to prevent premature edge failure.

• Sample Preparation: Test pieces are cut with precision cutting equipment ensuring clean, straight, and parallel edges. The samples must be free from machine marks, damage, or distortions and sized according to flute type specifications.

• Waxing Procedure: The loading edges of each test piece are dipped in molten paraffin to a depth of 6 mm and then blotted on heated paper towels. This treatment mitigates edge crushing effects and ensures failure occurs away from edges, improving test consistency.

• Testing Apparatus: Motor-driven compression testing machines following ISO 13820 specifications, along with guide blocks to align and support samples during testing.

• Conditioning and Sampling: Samples must be conditioned in a standard atmosphere prior to testing as per ISO 187. Sampling procedures per ISO 186 are recommended to ensure representative test data from corrugated materials, avoiding damaged or unrepresentative areas.

• Test Execution: The specimen is positioned on waxed edges, compression is applied at a controlled rate, and maximum force sustained is recorded.

• Precision and Reporting: Test precision is supported by comparative data; detailed test reports including specimen size, conditioning, maximum load, and failure observations are required.

Applications

• Quality Control in Packaging: Ensures that corrugated fibreboard and finished shipping cases meet performance requirements during manufacturing and conversion processes.

• Material Specification: Provides manufacturers and end-users with reliable ECT values to specify corrugated grades suitable for intended load-bearing applications.

• Design Validation: Supports structural testing and validation for packaging engineers to optimize board design and strength for transport resilience.

• Standard Compliance: Facilitates compliance with international standards and harmonizes ECT testing methods to improve data comparability globally.

• Durability Assessments: Assists in evaluating the resistance of corrugated boards to compressive forces encountered during handling, storage, and shipping.

Related Standards

• ISO 186: Paper and board - Sampling to determine average quality. Defines how to select representative samples for accurate testing.

• ISO 187: Paper, board and pulps - Standard atmosphere for conditioning and testing. Specifies atmospheric conditions to standardize moisture content and other environmental factors affecting test results.

• ISO 13820: Paper, board and corrugated fibreboard - Description and calibration of compression-testing equipment. Details apparatus requirements for compression strength testing.

By adhering to ISO 13821:2020, manufacturers and testing laboratories ensure consistent, accurate measurement of edgewise crush resistance in corrugated fibreboard, enabling better quality control, reliable packaging design, and improved supply chain performance. The waxed edge method minimizes edge effects seen in alternative test methods, making it a preferred approach for assessing compression strength relevant to end-use packaging applications.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13821
Second edition
2020-06
Corrugated fibreboard —
Determination of edgewise crush
resistance — Waxed edge method
Carton ondulé — Détermination de la résistance à la compression sur
chant — Méthode du bord paraffiné
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus and test liquid . 1
6 Sampling . 2
7 Conditioning . 3
8 Preparation of test pieces . 3
8.1 General . 3
8.2 Cutting the test pieces . 3
8.3 Waxing . 3
9 Procedure. 4
10 Calculation . 4
11 Precision . 4
11.1 General . 4
11.2 Precision data from TAPPI-CTS . 5
12 Test report . 5
Bibliography . 6
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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electrotechnical standardization.
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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
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www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 6/SC 2, Test methods and quality
specifications for paper and board.
This second edition cancels and replaces the first edition (ISO 13821:2002), of which it constitutes a
minor revision.
The main changes compared to the previous edition are as follows:
— Introduction of an additional group in the Introduction clause;
— Information on sampling of corrugated shipping containers are added in Clause 6;
— Information in 8.2 on the height of the test pieces;
— Introduction of precision data based on TAPPI comparative testing service.
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 2020 – All rights reserved

Introduction
A variety of methods for the determination of edgewise crush resistance are in use in different parts of
the world. These can be classified into four groups as follows:
a) Those in which a carefully cut rectangular test piece is tested without any special treatment or
modification.
b) Those in which the edges of the test piece to which the force is applied are waxed to prevent the
test result from being influenced by “edge effects”.
c) Those in which the test piece edges are not waxed but the shape of the test piece is such that the
length is substantially reduced at a point midway between the loading edges in order to induce the
failure to occur away from those edges.
d) Those in which carefully cut rectangular pieces are tested with edges clamped to prevent the test
result from being influenced by "edge effects".
The dimensions of the test piece vary from one group to the other and, in group c), the methods vary
according to the shape and method of reducing the length.
The methods may not give the same numerical results, but it can be shown that most of them can be
used to predict the top-to-bottom compression strength which will be achieved when the board is
properly converted into a transport package.
This document describes a method from group b) intended to be used for quality measurement and
quality specification purposes. This particular method is selected because it correlates well with the
top-to-bottom compression strength of the final transport package and provides significantly higher
results than unwaxed methods (a) because edge effects are avoided.
INTERNATIONAL STANDARD ISO 13821:2020(E)
Corrugated fibreboard — Determination of edgewise crush
resistance — Waxed edge method
1 Scope
This document specifies a method for the determination of the edgewise crush resistance of corrugated
fibreboard. The force is applied in the direction of the flute axis.
This method is applicable to single-wall (double-faced), double-wall, and triple-wall corrugated
fibreboard. It may also be used to test samples taken from corrugated cases and other converted
products.
While the method is applicable to waxed corrugated fibreboard, care must be taken that the heat used
in the waxing step does not affect the corrugated structure. This is controlled by observing that failure
during the test still occurs away from the loaded edges.
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 13820, Paper, board and corrugated fibreboard — Description and calibration of compression-testing
equipment
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
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