ISO 2426-2:2020

Plywood - Classification by surface appearance - Part 2: Hardwood

This document specifies the nature and limits of characteristics inherent in wood and manufacturing defects enabling the visual assessment of the plywood for allocation to an appearance class. This document applies to plywood, the surface veneers of which are made from hardwood species[1] including tropical and temperate hardwood. It does not apply to overlaid panels. [1] Conventionally, broadleaved species.

Contreplaqué — Classification selon l'aspect des faces — Partie 2: Bois feuillus

General Information

• Status: Published
• Publication Date: 06-Apr-2020
• ICS: 79.060.10 - Plywood
• Technical Committee: ISO/TC 89/SC 3 - Plywood
• Drafting Committee: ISO/TC 89/SC 3 - Plywood
• Current Stage: 9060 - Close of review
• Completion Date: 02-Dec-2030

Relations

• Consolidated By: ISO 17225-8:2023 - Solid biofuels - Fuel specifications and classes - Part 8: Graded thermally treated and densified biomass fuels for commercial and industrial use
• Effective Date: 06-Jun-2022
• Revises: ISO 2426-2:2000 - Plywood - Classification by surface appearance - Part 2: Hardwood
• Effective Date: 15-Dec-2017

Overview

ISO 2426-2:2020 is an international standard providing a systematic classification for plywood made from hardwood species, based on surface appearance. This standard focuses on visual assessment criteria that define quality classes for hardwood plywood veneers, including both tropical and temperate broadleaved hardwood species. It serves as a key reference for manufacturers, suppliers, and users in evaluating the appearance of hardwood plywood and determining its suitability for various applications.

This document is part two of the ISO 2426 series and specifically excludes plywood panels that are overlaid or coated. The visual classification addresses inherent wood characteristics and manufacturing defects, providing clear guidelines for permissible surface features within specified appearance classes.

Key Topics

• Scope and Application
  ISO 2426-2:2020 applies exclusively to plywood surfaced with hardwood veneers. It defines the acceptable nature and limits of defects and characteristics found naturally in wood or resulting from manufacturing processes to allocate each plywood panel to one of five appearance classes: E, I, II, III, or IV.

• Appearance Classes and Criteria
  The standard categorizes hardwood plywood surface quality into classes based on:

  • Presence and size of knots (pin knots, sound intergrown knots, unsound knots)
  • Splits and checks, both open and closed
  • Discoloration and irregularities in the wood structure
  • Defects caused by insects, parasitic plants, marine borers, and fungal decay
  • Manufacturing defects such as open joints, overlaps, blisters, roughness, glue penetration, and particles

• Permissible Defects and Characteristics
  Detailed tables in the standard specify limits for each defect type in terms of size, frequency, and condition (filled or unfilled). For example, pin knots up to 3 mm in diameter are generally permitted in all classes, whereas unsound knots and knot holes have stricter size and filling requirements depending on the class. Manufacturing defects like open joints and overlaps have defined permissible widths and quantities depending on the class.

• Visual Assessment Process
  The evaluation follows procedures outlined in ISO 2426-1, ensuring consistency in the classification of hardwood plywood based on surface appearance.

Applications

ISO 2426-2:2020 is essential for stakeholders involved in the production, quality control, specification, and procurement of hardwood plywood. Practical applications include:

• Quality Control in Manufacturing
  Producers use this standard to classify plywood batches, ensure conformity with customer requirements, and reduce variability in product aesthetics.

• Specification and Procurement
  Architects, designers, and builders reference the standard to select plywood that meets visual and aesthetic expectations for furniture, interior paneling, cabinetry, and decorative applications.

• Compliance and Certification
  Certification bodies and inspection agencies employ the classification system to verify product quality claims and adherence to international norms.

• Market Standardization
  Trade and commerce benefit from a unified terminology and classification system, enhancing communication across suppliers and customers worldwide.

Related Standards

• ISO 2426-1: General Classification by Surface Appearance
  Provides overarching principles and methods for evaluating plywood surface quality, forming the basis for part 2’s hardwood-specific criteria.

• ISO 2426-3: Softwood Plywood Classification
  Complements part 2 by detailing classification requirements for plywood made with softwood veneers.

• ISO 1096: Plywood Classification
  Covers general classification principles relevant to plywood quality.

• ISO 2074: Plywood Vocabulary
  Offers standardized terminology for plywood products and defects.

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Keywords: ISO 2426-2, plywood classification, hardwood plywood, surface appearance, plywood defects, hardwood veneer, plywood standards, plywood quality, visual assessment, manufacturing defects, hardwood species, plywood surface grading.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 2426-2
Second edition
2020-04
Plywood — Classification by surface
appearance —
Part 2:
Hardwood
Contreplaqué — Classification selon l'aspect des faces —
Partie 2: Bois feuillus
Reference number
©
ISO 2020
© ISO 2020
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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below or ISO’s member body in the country of the requester.
ISO copyright office
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Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents  Page
Foreword .iv
1  Scope . 1
2  Normative reference . 1
3  Terms and definitions . 1
4  Classification by surface appearance . 1
4.1 Appearance classes . 1
4.2 Permissible characteristics and defects . 1
4.2.1 General. 1
4.2.2 Characteristics inherent in wood . 2
4.2.3 Manufacturing defects . 3
Bibliography . 5
Foreword
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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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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 89, Wood-based panels, Subcommittee
SC 3, Plywood.
This second edition cancels and replaces the first edition (ISO 2426-2:2000), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— It is precised that hardwood species includes tropical and temperate hardwood.
A list of all parts in the ISO 2426 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 2020 – All rights reserved

INTERNATIONAL STANDARD ISO 2426-2:2020(E)
Plywood — Classification by surface appearance —
Part 2:
Hardwood
1  Scope
This document specifies the nature and limits of characteristics inherent in wood and manufacturing
defects enabling the visual assessment of the plywood for allocation to an appearance class.
1)
This document applies to plywood, the surface veneers of which are made from hardwood
...