ISO 1924-3:2005

Overview

ISO 1924-3:2005 specifies a laboratory method for determining the tensile properties of paper and board using a constant rate of elongation (100 mm/min). The standard covers measurement and calculation of tensile strength, strain at break, tensile energy absorption, tensile stiffness, tensile index, tensile energy absorption index, tensile stiffness index and modulus of elasticity. It is applicable to most paper and board grades (including high-extensibility papers) except low-density tissue products for which ISO 12625-4 is recommended.

Key topics and technical requirements

• Test conditions
  • Constant elongation rate: 100 mm/min ± 10 mm/min
  • Test span (distance between clamping lines): 100 mm ± 0.5 mm
  • Test piece width: 15.0 mm ± 0.1 mm
• Apparatus and accuracy
  • Tensile testing machine with load cell and elongation recorder.
  • Force accuracy: ≈ 1% of true force for strength and energy values.
  • Elongation accuracy: 0.1 mm for strain at break; 0.01 mm in 0–1 mm range for tensile stiffness.
  • Clamps must produce parallel clamping lines and hold specimens without slip or damage; geometric tolerances (clamping-line parallelism and alignment) are specified within 1° (angle change during test ≤ 0.5°).
• Specimen preparation and conditioning
  • Sampling per ISO 186; conditioning per ISO 187.
  • Grammage and thickness measured by ISO 536 and ISO 534 when indices or modulus are required.
  • Avoid contamination, moisture changes and handling that alter test-piece moisture content.
• Calculations and reporting
  • Equations in the standard specify how to compute the various indices and modulus.
  • The standard notes that results are sensitive to test span and rate of elongation; comparisons with other methods (e.g., ISO 1924-2 at 20 mm/min / 180 mm span) may show systematic differences (an increase of about 5–15% in tensile strength was observed in one study when moving to 100 mm/min/100 mm span).

Applications and users

ISO 1924-3:2005 is used for:

• Quality control and production monitoring in paper mills.
• Incoming/outgoing inspection by converters and packaging manufacturers.
• R&D and product development for material formulation and processing.
• Laboratory intercomparisons and specification testing for contracts and tendering. Typical users: laboratory technicians, QA engineers, material scientists, paper technologists and standards bodies.

Related standards

• ISO 1924-2 - Constant rate of elongation method (20 mm/min, 180 mm span)
• ISO 12625-4 - Tissue paper tensile testing (recommended for tissue)
• ISO 186, ISO 187, ISO 534, ISO 536 - sampling, conditioning, thickness and grammage referenced for specimen preparation and normalization

Keywords: ISO 1924-3:2005, paper tensile properties, constant rate of elongation, tensile strength, tensile stiffness, tensile index, tensile energy absorption.