ISO 34256:2024

Overview

ISO 34256:2024 specifies a laboratory test method for resistance to static load of joints bonded with a thermoplastic adhesive for non‑structural wood applications. The standard determines the ability of a bonded test piece to support a constant shear load for a specified time without fracture or excessive distortion and sets a performance requirement for mean survival time. ISO 34256 is intended to be used alongside ISO 19209 and ISO 19210, which describe durability classes and tensile shear test methods for non‑structural wood adhesives.

Key topics and requirements

• Scope: Test of thin glue‑line lap joints made with thermoplastic adhesives for non‑structural wood uses.
• Test specimen: Symmetrical single lap joint with an overlap of (20.0 ± 0.2) mm (thin glue line as per ISO 19210).
• Loading and environment:
  • Constant shear load applied by hanging (30.0 ± 0.5) kg weights from a jig.
  • Climatically controlled environment at (23 ± 2) °C and (50 ± 5) % RH (standard 23/50).
  • Test duration up to 21 days or until a mean endurance of 14 days is achieved.
• Failure criteria: Joint fracture or excessive deflection such that the jigs contact each other. Daily inspections record time to failure (in days).
• Acceptance: Mean survival time must not be less than 14 days for the sample of 10 test pieces. Report individual survival times, mean and standard deviation.
• Test report requirements: Adhesive identification, batch, application and pressing parameters, wood species and moisture content (EN 13183‑1/2), number of specimens, deviations, and test dates.

Applications and who uses this standard

ISO 34256 is relevant for:

• Adhesive manufacturers validating product performance for non‑structural wood applications.
• Test laboratories performing conformity and comparative static‑load testing.
• Wood product manufacturers (furniture, cabinetry, interior joinery) specifying adhesives for applications where long‑term static loads may occur.
• Purchasers and specifiers who require an additional static‑load performance assurance beyond standard durability classes.
• Quality and compliance engineers documenting adhesive performance for procurement or product claims.

Practical value: ISO 34256 helps stakeholders assess the long‑term static load resistance of thermoplastic adhesives in controlled conditions, supporting product selection and procurement decisions for non‑structural wood assemblies.

Related standards

• ISO 19209 - Classification of thermoplastic wood adhesives for non‑structural applications (durability classes D1–D4).
• ISO 19210:2017 - Tensile shear strength of lap joints; thin glue‑line preparation.
• EN 923, EN 13183‑1/2 - Terms/definitions and moisture content determination referenced in the test method.