ISO 2426-2:2020

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.

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.