Overview
EN ISO 9073-14:2023 - Nonwovens: Coverstock wetback (simulated urine) defines a laboratory test method to measure the tendency of diaper coverstock (nonwoven topsheets) to transport liquid back onto the skin after the liquid has penetrated the coverstock. Published in 2023 and approved by CEN/ISO, this method is intended for quality control and comparative evaluation of nonwoven coverstocks and surface treatments. It does not simulate in-use conditions for finished products.
Key topics and technical requirements
- Test objective: Quantify wetback - the mass of liquid that migrates back onto a pickup paper after repeated liquid dosing.
- Test liquid (simulated urine): 9 g/L sodium chloride in demineralized water with surface tension (70 ± 2) mN/m (checked before tests).
- Strike-through principle: The procedure corresponds with repeated liquid strike-through time (NWSP 070.7). A specimen is loaded three times; after the final dose a simulated baby weight ensures even liquid distribution.
- Blotter and pickup paper: Absorbent pad = 7 layers of blotter paper (100 × 100 mm) meeting defined mass per unit area and absorption capacity (e.g., mass ~139 ± 11 g/m2; liquid capacity ≥480%; first STT ≤2 s without sample). Pickup paper is 125 × 125 mm with the same specifications.
- Apparatus: Burette or pipette, controlled discharge funnel, strike-through plate with electrodes (transparent acrylic plate), electronic timer, and a simulated baby weight (SBW).
- Measurement: After dosing and application of SBW, a pre-weighed pickup paper is applied. The mass of liquid absorbed by pickup paper is reported as wetback.
- Scope of use: Designed for comparative testing and production lot inspection; includes conditioning, sampling, procedure, expression of results, precision data and reporting requirements.
Practical applications and users
- Nonwovens manufacturers assessing coverstock formulations and surface treatments
- Diaper and incontinence product R&D teams optimizing comfort and skin safety
- Quality control and third-party testing laboratories performing batch comparison
- Procurement/specification engineers requiring objective wetback data for supplier selection
- Regulatory and standards bodies referencing harmonized test methods
Related standards
- ISO 9073 series (nonwovens test methods)
- ISO 9073-13 / NWSP 070.7 (repeated liquid strike-through time)
- ISO 9092 (nonwovens vocabulary)
- ISO 139 (conditioning and testing atmospheres)
- NWSP 005.0, NWSP 010.1 (nonwoven sampling and absorption methods)
EN ISO 9073-14:2023 provides a reproducible, industry-accepted wetback test for nonwoven coverstocks - essential for product comparison, process control and material specification in diaper and hygiene product manufacturing.
