Overview
EN ISO 9073-13:2023 - "Nonwovens - Test methods - Part 13: Repeated liquid strike-through time (simulated urine)" is a CEN-endorsed ISO test method for measuring the strike-through time (STT) of nonwoven coverstocks. The method quantifies the time required for each of three successive aliquots of simulated urine to pass through a test specimen into a defined absorbent pad, using conductometric detection and electronic timing. It is intended for quality control and comparative testing of coverstock materials and does not simulate final in-use conditions of finished products.
Key topics and technical requirements
- Test principle: Three sequential doses of simulated urine are released on a nonwoven specimen placed over a reference absorbent pad; the time for each dose to penetrate (STT) is recorded.
- Simulated urine: 9 g/l sodium chloride solution with surface tension (70 ± 2) mN/m at (23 ± 2) °C; surface tension must be checked before test series.
- Absorbent pad (blotter): 7 layers of 100 mm × 100 mm blotter paper (smooth side up). Required properties include mass per unit area (139 ± 11 g/m²), liquid absorption capacity ≥ 480% (per NWSP 010.1), and mean first strike-through ≤ 2 s without a test specimen.
- Apparatus: Strike-through tester with conductometric electrodes and electronic timer; delivery by 50 ml burette or 5 ml pipette. Annex B provides detailed apparatus figures.
- Procedure controls: Conditioning, sampling, reagent quality (grade 3 water), instrument calibration/verification, and specific reporting items (including blotter paper identification and manufacturer) are mandated.
- Scope limitation: Designed for comparison and QC of nonwoven coverstocks only - it does not replicate product usage.
Applications and users
- Manufacturers of nonwoven coverstocks for hygiene products (diapers, adult incontinence pads) using STT to screen materials.
- R&D and product development teams comparing coverstock formulations and surface treatments.
- Quality control and laboratory testing services performing batch acceptance and supplier comparisons.
- Standards bodies and testing equipment manufacturers developing or validating strike-through testers and test protocols.
Related standards
- ISO 9092 (Nonwovens - Vocabulary)
- ISO 11224 (Textiles - Web formation and bonding in nonwovens - Vocabulary)
- ISO 139 (Conditioning and testing atmospheres)
- ISO 3696 (Water for analytical use)
- NWSP 010.1 and NWSP 070.7 (industry procedures referenced for absorbency and STT)
EN ISO 9073-13:2023 is the second edition (June 2023) prepared by ISO/TC 38 in collaboration with CEN/TC 248 and supersedes the 2007 version. This standard is essential for reproducible, comparable STT data in material selection and quality control of nonwoven coverstocks.
