ISO 12625-12:2023

Overview

ISO 12625-12:2023 - "Tissue paper and tissue products - Part 12" specifies a laboratory test method for measuring the tensile strength of perforated lines in tissue products and for calculating perforation efficiency. The method uses a tensile-testing apparatus operating at a constant rate of elongation and is intended specifically for measuring machine-direction tensile strength (i.e., cross-direction perforations). The standard defines sampling, conditioning, test-piece preparation, test procedure, calculations and reporting requirements.

Key topics and technical requirements

• Test principle: Stretch perforated and non‑perforated test pieces to break at a constant rate of elongation and record tensile force vs. elongation to determine tensile strength.
• Rate of elongation: Expressed as a percentage of the initial test span - nominally 50 %/min (e.g., 50 mm/min for 100 mm span, 25 mm/min for 50 mm span) with specified tolerances.
• Test span and clamps: Test span typically 100 ±1 mm or 50 ±1 mm when product geometry requires. Clamping lines must be parallel within 1°; clamps at least 50 mm wide and designed to avoid damage or slippage.
• Force measurement: Load cell accuracy must meet ±1 % of reading or ±0.025 N, complying with ISO 7500-1.
• Specimen dimensions: Standard width 50 ±0.5 mm; specimen length requirements vary by distance between perforations (≥150 mm, <150 mm, <75 mm) - the standard specifies minimum lengths and placement of perforations.
• Sample size: Cut enough pieces to obtain 10 valid results for both perforated and non‑perforated specimens per sample.
• Calculations: Tensile strength is derived from maximum force per unit width. Perforation efficiency (Ep) = (difference between non‑perforated and perforated tensile strengths) ÷ non‑perforated tensile strength, expressed as a percentage.
• Annexes: Informative annexes cover the influence of pre‑cuts, paper ageing and method precision.

Practical applications

• Quality control of toilet tissue, kitchen towels and other perforated tissue products to ensure reliable sheet separation and product cohesion.
• Process optimization for converting and perforation die design: balance between enough strength for handling vs. ease of separation.
• R&D testing for new tissue grades, embossing or perforation patterns.
• Contract and supplier testing to verify product performance and compliance.

Who uses this standard

• Tissue manufacturers and converting lines
• Independent testing laboratories and QC teams
• R&D engineers and product developers
• Procurement/specification writers and regulatory bodies

Related standards

• ISO 12625-1 (vocabulary)
• ISO 12625-4 (tensile test methods & cutting device)
• ISO 1924-2 (constant rate of elongation tensile testing)
• ISO 187 (conditioning) and ISO 186 (sampling)
• ISO 7500-1 (force-measuring system calibration)

Keywords: ISO 12625-12:2023, tissue paper, perforation efficiency, tensile strength, tensile-testing, perforated lines, machine-direction testing.