ISO 9073-13:2023

Overview

ISO 9073-13:2023 - "Nonwovens - Test methods - Part 13: Repeated liquid strike-through time (simulated urine)" defines a laboratory test method to measure the strike-through time (STT) of nonwoven coverstocks. The procedure records the time for each of three successive doses of a simulated urine solution to pass through a nonwoven specimen into a standard absorbent pad. The method is intended for quality control and comparative testing between coverstock materials; it explicitly does not simulate in-use conditions of finished hygiene products.

Key topics and technical requirements

• Test principle: Three successive doses of simulated urine are discharged at a prescribed rate onto a specimen resting on a reference absorbent pad; penetration time is detected conductometrically and timed electronically.
• Simulated urine: 9 g/L sodium chloride solution in demineralized water with surface tension (70 ± 2) mN/m at 23 °C (check prior to testing).
• Absorbent pad (blotter paper): 7 layers (100 × 100 mm), mass per unit area (139 ± 11) g/m², minimum liquid absorption capacity ≥ 480 %, and first STT ≤ 2 s when tested without a specimen.
• Apparatus: Strike-through tester with a funnel/magnetic valve capable of discharging 25 mL in (3.5 ± 0.25) s; electrode plate and baseplate (transparent acrylic); conductivity detector with ~0.05 s response; threshold voltage typically ~0.150 V; timing accuracy to 0.01 s.
• Calibration & verification: Includes a calibration orifice for passage-time verification (e.g., 10 mL in ~2 s) and equipment checks per Clause 9.
• Sampling & conditioning: Samples conditioned per ISO 139; sampling guidance references ISO 186, ISO 2859-1, ISO 3951-1 and NWSP sampling documents.
• Reporting and precision: Detailed requirements for test report content and precision data are provided; Annex A and B supply precision guidance and apparatus figures.

Practical applications - who uses this standard

• Nonwovens manufacturers: routine quality control and lot-to-lot comparison of coverstock penetration performance.
• Product developers / R&D: comparing alternative coverstock formulations or surface treatments for liquid handling.
• Third‑party test laboratories: standardized method for contract testing of coverstock STT.
• Procurement & quality assurance teams**: verifying supplier claims and acceptance testing of incoming materials. Note: Because ISO 9073-13:2023 measures laboratory strike-through under controlled conditions, results should be interpreted for material comparison rather than as a direct predictor of finished-product in-use performance.

Related standards (select)

• ISO 139 - standard atmospheres for conditioning
• ISO 186 - sampling to determine average quality
• ISO 9092, ISO 11224 - nonwoven vocabulary / web formation terms
• ISO 3696 - water for analytical use
• NWSP 010.1, NWSP 005.0, NWSP 070.7 - industry guidance for nonwoven absorption and sampling

Keywords: ISO 9073-13:2023, nonwovens, strike-through time, STT, simulated urine, test method, conductometric detection, absorbent pad, quality control.