ISO 9073-8:2025

Overview

ISO 9073-8:2025 - Nonwovens - Test methods - Part 8 specifies a laboratory method to measure the liquid strike‑through time of nonwoven coverstocks using simulated urine. The test determines how long a known volume of liquid takes to pass through a nonwoven specimen into a reference absorbent pad. This method is intended for comparative testing of coverstock materials (e.g., diaper or sanitary product cover layers) and explicitly does not simulate the full in‑use performance of finished products.

Key topics and technical requirements

• Test principle: A controlled volume and flow rate of simulated urine is discharged onto a conditioned nonwoven specimen placed over a reference absorbent pad. Penetration is detected electrically and timed.
• Simulated urine: 9 g/L sodium chloride in grade 3 water (ISO 3696); target surface tension about 70 ± 2 mN/m. Any surfactant addition to alter surface tension must be reported.
• Reference absorbent pad: Five layers of specified filter paper (100 × 100 mm); mean strike‑through time without nonwoven ≈ 3 ± 0.5 s.
• Apparatus: Includes a 50 ml burette, funnel with magnetic valve (controlled discharge rate), a transparent strike‑through plate (≈500 g) with corrosion‑resistant electrodes (Ø 1.6 mm) and an electronic timer readable to 0.01 s.
• Specimens & conditioning: Cut 125 × 125 mm specimens (minimum 10 tests per sample), conditioned per ISO 139 standard atmospheres; sampling per ISO 186.
• Procedure essentials: Centre the funnel 30 mm above specimen, discharge 5.0 ml per test; timer starts when liquid completes the circuit and stops when liquid falls below electrode level.
• Results & reporting: Report individual times, mean strike‑through time, coefficient of variation, conditioning atmosphere, any surfactant used, and deviations from the procedure.

Applications and who uses this standard

• Manufacturers and R&D teams of diapers, incontinence and sanitary products for material selection and formulation of coverstocks.
• Quality control laboratories performing comparative absorbency/penetration tests on incoming or produced nonwovens.
• Suppliers and procurement teams for performance benchmarking between nonwoven batches or different suppliers.
• Test houses validating lab equipment and methods for strike‑through measurements.

Practical benefits include reproducible comparative data for product development, supplier qualification, and process control. Note: results are comparative material properties and should not be taken as direct indicators of finished‑product wearer performance.

Related standards

• ISO 139 - Standard atmospheres for conditioning and testing
• ISO 186 - Sampling to determine average quality
• ISO 3696 - Water for analytical laboratory use
• ISO 9073 series - Other nonwoven test methods

Keywords: ISO 9073-8:2025, nonwovens test methods, liquid strike-through time, simulated urine, coverstocks, diaper coverstock testing, absorbency testing, strike-through plate.