Overview
ISO 13061-13:2024 specifies a standard test method for determining linear radial and tangential shrinkage of wood using small clear specimens. Part of the ISO 13061 series on the physical and mechanical properties of wood, this second edition updates dimensions and measurement requirements for test pieces and establishes a reproducible procedure for comparing dimensional stability across species, batches and treatments.
Key Topics and Requirements
- Scope: Measurement of linear shrinkage in the radial and tangential directions from green (or fully saturated) to oven-dry condition.
- Test pieces: Rectangular prisms cut from green wood, at least 20 mm square in the radial and tangential directions and ≥5 mm along the grain. Annual-ring inclination to tangential faces shall not exceed 10°.
- Measurement points: Marked at the centre of tangential and radial faces; dimensions measured to 0.02 mm accuracy.
- Apparatus:
- Measuring instrument with parallel flat ends (5–8 mm diameter) and 0.02 mm precision.
- Forced-convection oven maintained at 103 ± 2 °C.
- Desiccator, vessel of distilled water and a balance accurate to 0.001 g.
- Procedure:
- Ensure specimens are at or above the fibre saturation point (FSP); if below, soak in distilled water at 20 ± 2 °C and monitor until dimensional changes ≤ 0.02 mm (checks every 3 days).
- Dry to constant mass at 103 ± 2 °C, checking mass every 8 h until mass change ≤ 0.2% or dimensional changes ≤ 0.02 mm.
- Cool in a desiccator and re-measure radial and tangential dimensions.
- Calculation and reporting: Linear shrinkage expressed as percentage change from green to oven-dry dimensions, results rounded to 0.1%, with mean and standard deviation reported. Test report includes sampling details, measurement methods, results, date and testing organization.
Applications and Users
ISO 13061-13 is used by:
- Timber testing laboratories and wood science researchers for dimensional stability characterization.
- Quality control teams in lumber, furniture, flooring and engineered wood manufacturing to assess shrinkage-related performance.
- Engineers and designers requiring shrinkage data for structural design, joinery, drying schedules and moisture-related deformation analysis.
- Standards bodies and certification schemes that need reproducible, comparable shrinkage data across species and treatments.
Practical benefits include improved drying protocols, reduced warping/checking in production, and reliable input data for structural calculations and moisture-control strategies.
Related Standards
- ISO 3129 - Sampling and general requirements for small clear wood specimens
- ISO 24294 - Timber vocabulary
- Other parts of the ISO 13061 series covering mechanical and physical test methods for wood
Keywords: ISO 13061-13, radial shrinkage, tangential shrinkage, wood testing, physical and mechanical properties of wood, test methods for small clear wood specimens.
Open preview (PDF)Physical and mechanical properties of wood — Test methods for small clear wood specimens — Part 13: Determination of radial and tangential shrinkage
