SIST EN 975-2:2005

Overview

SIST EN 975-2:2005 is a European standard developed by CEN that defines appearance grading criteria for sawn hardwood timber, specifically for European poplars. This standard applies to both green and dry sawn timber with thickness ranging from 15 mm up to 34 mm, and widths between 100 mm and 250 mm (measured in the green state). It focuses solely on the visual grading of appearance and explicitly excludes strength grading for structural timber. SIST EN 975-2:2005 forms part of a wider series of standards addressing the appearance grading of various hardwood species.

The standard provides a comprehensive and consistent framework to classify poplar timber based on visual quality parameters such as knots, wane, grain abnormalities, and defects. This ensures uniformity and reliability in grading, facilitating timber trading and quality assurance in woodworking and manufacturing industries.

Key Topics

• Scope and Application

  • Applies to European poplars in sawn timber form
  • Covers timber thickness of 15-34 mm and width 100-250 mm
  • Primarily focused on appearance grading, not structural strength grading

• Grading Rules and Methodology

  • Each face of the timber is graded separately; piece grade depends on the worst face or edge
  • Grades are assigned based on limits of defects and features present on the timber surfaces
  • Four distinct appearance grades which dictate allowable size and quantity of defects

• Assessment of Features

  • Features measured according to EN 1310
  • Knots: Differentiated by size, form, condition (sound, loose, intergrown)
  • Wane: Bark presence prohibited
  • Considerations for other common timber defects such as bark pockets, reaction wood, discoloration, insect attack, and warp

• Limits for Defects

  • Detailed maximum approved limits for knots, wane, checks, shakes, and discoloration for each grade
  • Includes specific measurements such as percentage of width or thickness that knots may occupy
  • Defines peel limits such as cup, bow, spring, and twist percentages to determine acceptable warp

• Conformity and Quality Control

  • Ensures graded lots maintain an even distribution of quality
  • Conformity assessed according to ENV 12169 standards for lots of sawn timber

Practical Applications

• Wood Processing Industry
  SIST EN 975-2:2005 enables manufacturers, sawmills, and timber merchants to grade poplar boards consistently, facilitating quality control and product classification based on appearance.

• Furniture and Interior Design
  Poplar timber graded under this standard meets aesthetic expectations required for visible purposes like furniture, paneling, and decorative carvings where surface appearance is critical.

• Retail and Export
  Clear classification assists traders in marketing timber with reliable appearance grades, supporting transparency in sales and compliance with client specifications.

• Wood Product Certification
  By following this standardized grading, suppliers can certify product quality and meet customer or regulatory requirements promptly.

Related Standards

• EN 975-1: Appearance grading of hardwoods - Part 1: Oak and Beech – complements Part 2 by covering other common hardwood species.
• EN 1611-1: Appearance grading of softwoods - Part 1: European spruces, firs, pines, and Douglas firs – provides grading rules for softwood species.
• EN 1310: Method of measurement of timber features – referenced for assessment methodology within EN 975-2.
• ENV 12169: Criteria for conformity assessment of sawn timber batches – guides conformity testing to ensure grade consistency.
• EN 844 series: Glossary and terminology standards for timber, defining terms critical for standardized communication within timber grading.

By implementing SIST EN 975-2:2005, stakeholders within the European timber sector can achieve a harmonized approach to grading poplar sawn timber based on visual appearance, promoting product quality, trade consistency, and consumer confidence across markets.