Overview
ISO 4475:1989 specifies standardized methods for measuring visible defects in coniferous and broadleaved tree sawlogs. It defines how to quantify defects such as knots, shakes, curvature, root swellings, ovality, sapwood/heartwood anomalies, fungal damage, char and mechanical damage. The standard cross‑references ISO 4473 (classification) and ISO 4474 (terms and definitions) and includes illustrated examples (13 figures). Where linear measurement is specified, values are in whole centimetres rounded down to the nearest centimetre.
Key topics and requirements
- Scope and linkage: Applies to coniferous and broadleaved sawlogs and uses definitions/classification in ISO 4473 and ISO 4474.
- Measurement units and rounding: Linear measurements in whole centimetres, rounded off to the nearest centimetre below.
- General rule: It is permitted to measure only one of the indicated parameters where multiple options are shown.
- Defect measurement methods (examples):
- Knots: Measured by the minimum diameter; knot callus excluded.
- Shakes (heart, ring, side): Measured by minimum thickness of the affected out‑cut or by length/width; some varieties (e.g., ring shake in broadleaved logs) are noted but not measured.
- Curvature (simple/compound): Expressed as deviation from straightness over the piece length, as a percentage of curvature length or as fraction of end diameter; compound curves require counting curves and summing deviations.
- Root swelling and inbark: Measured by differences between butt-end diameters and diameters measured 1 m from the butt.
- Ovality and tapering: Measured as differences between greater and lesser diameters or as cm per meter.
- Fungal and sap defects, rot, char: Measured as area percentages of the end or as minimum thickness of the affected out‑cut.
- Mechanical damage and insect holes: Measurement rules vary by type - many small surface holes are noted; larger or mass damage is quantified by dimensions or length per metre.
Practical applications
- Standardizes log grading, scaling and quality control for sawmills, log traders and wood processors.
- Supports timber procurement, contract specifications and pricing based on measurable defect metrics.
- Used by forest managers, log inspectors, certification bodies and researchers to ensure consistent reporting of sawlog defects.
- Useful for operational decisions: sawline optimization, yield estimation and sorting of logs by end‑use suitability.
Related standards
- ISO 4473 - Classification of visible defects in sawlogs (referenced)
- ISO 4474 - Terms and definitions for visible defects in sawlogs (referenced)
Keywords: ISO 4475:1989, sawlogs, visible defects measurement, coniferous, broadleaved, log grading, knots, shakes, curvature, timber quality.
