ISO 9073-14:2023

Overview - ISO 9073-14:2023 (Coverstock wetback, simulated urine)

ISO 9073-14:2023 is an international test method for nonwovens that specifies how to measure coverstock wetback - the transport of liquid back through a diaper coverstock onto the skin - using a simulated urine solution. Intended primarily for quality control and comparative evaluation of different nonwoven coverstocks and surface treatments, this method corresponds with repeated liquid strike-through time (NWSP 070.7). It is explicit that the test is for material comparison and does not simulate in-use conditions of finished products.

Key topics and technical requirements

• Test principle: Repeated dosing of a coverstock placed over a standard absorbent pad (blotter paper) and measurement of liquid transferred onto a pre‑weighed pick‑up paper after application of a simulated baby weight (SBW).
• Simulated urine: 9 g/l sodium chloride solution in demineralized water, surface tension (70 ± 2) mN/m at (23 ± 2) °C.
• Absorbent pad / pick‑up paper: 7 layers (100 × 100 mm) for the pad; pick‑up paper 125 × 125 mm. Blotter specifications include mass per unit area (139 ± 11 g/m²) and minimum liquid absorption capacity (≥ 480%).
• Apparatus essentials: burette or pipette; funnel with magnetic valve (25 ml delivered in 3.5 ± 0.25 s); strike‑through plate (25 mm acrylic, ~500 ± 5 g) with corrosion‑resistant electrodes; electronic timer; simulated baby weight (4 000 ± 20 g) with specified foam and polyethylene film.
• Sampling & conditioning: Conditioning to ISO 139 standard atmosphere; sampling guidance references NWSP 005.0 and ISO sampling standards (ISO 2859‑1, ISO 3951‑1). Typical sample size recommendations and lot/sample considerations are included.
• Calculation and reporting: Wetback expressed as the mass of liquid absorbed by pick‑up paper; the method references loading factor calculations and links to ISO 9073‑13 for repeated strike‑through procedures.

Practical applications

• Quality control and batch comparison of diaper coverstock materials and hydrophobic/hydrophilic surface treatments.
• R&D screening of new nonwoven formulations to assess resistance to liquid re‑wettability.
• Supplier and purchaser material specifications where objective comparison of wetback performance is required.

Who should use this standard

• Nonwovens manufacturers and converters producing diaper coverstock.
• Product development and quality assurance teams in hygiene product companies.
• Laboratory technicians performing comparative absorbency and wetback tests.
• Procurement specialists specifying material acceptance criteria.

Related standards

• ISO 9073‑13 (Repeated liquid strike‑through time)
• ISO 139 (Conditioning)
• ISO 9092, ISO 11224 (Vocabulary)
• NWSP 070.7, NWSP 005.0, NWSP 010.1
• ISO 2859‑1, ISO 3951‑1 (Sampling)
• ASTM D3574 (foam specifications)

Keywords: ISO 9073-14:2023, nonwovens, coverstock wetback, simulated urine, diaper coverstock, wetback test, strike-through, quality control, blotter paper, simulated baby weight.