Breathability testing measures the ability of leather used in sporting goods—such as gloves, footwear uppers, and sports balls—to transmit water vapor and air, a property that directly governs athlete comfort, hygiene, and in-use performance. This technical article explains the testing principle, applicable ISO, ASTM, EN, and GB standards, sample requirements, test methods, and typical evaluation criteria for leather permeability assessment performed by accredited third-party laboratories.
Technical Overview
Leather breathability refers to the capacity of the material to allow water vapor (perspiration) and air to pass through its porous, three-dimensional collagen fiber network. In sporting goods applications, this property is critical: it determines how effectively a boxing glove, golf glove, athletic shoe upper, or ball cover dissipates body heat and moisture during intense physical activity. Poor breathability leads to sweat accumulation, loss of grip, microbial growth, odor formation, premature stiffening, and accelerated material degradation.
Breathability is quantified through two principal parameters: water vapor permeability (also expressed as water vapor transmission rate, WVTR) and air permeability. Both values are strongly influenced by the leather's origin, thickness, tanning system, fatliquoring level, and the thickness and type of finishing coatings applied to the grain surface. Accredited third-party laboratories evaluate these parameters using internationally recognized methods to support product development, quality control, and compliance verification.
- ISO 14268:2012 – Leather – Physical and mechanical tests – Determination of water vapour permeability
- ISO 17229:2016 – Leather – Determination of water vapour absorption and desorption
- ASTM E96/E96M – Standard Test Methods for Water Vapor Transmission of Materials (dish method)
- ISO 9237:1995 – Determination of the permeability of fabrics to air (applied to leather and coated substitutes)
- ASTM D737 – Standard Test Method for Air Permeability of Textile Fabrics (applied to coated and textile-based leather substitutes)
- GB/T 4689.21 – Chinese national standard for determination of water vapour permeability of leather
- ISO 2419 and ISO 2418 – Conditioning and sampling of leather test specimens
Testing Samples
Natural Leather for Sports Gloves
Cowhide, goatskin, sheepskin, pigskin, and light calf leathers used in boxing and martial arts gloves, baseball and softball gloves, golf gloves, goalkeeper gloves, cycling gloves, and equestrian riding gloves. These materials are typically chrome-tanned with moderate finishing, and specimens should be taken from areas representative of actual production, such as the palm panel or back-of-hand cut positions.
Leather for Athletic Footwear Uppers
Full-grain, nubuck, suede, and exotic light leathers (such as kangaroo or calf) used in soccer boots, running shoes, indoor court shoes, and hiking footwear. Because upper leather is frequently pigmented, glazed, or laminated with membranes, each finishing variant should be submitted as a separate test condition.
Leather for Balls, Straps, and Protective Equipment
Cover leathers for training balls, weightlifting belts, martial arts protectors, gymnasium grip pads, equestrian tack, and racket grip wraps. For these thicker, more densely finished leathers, breathability data help predict moisture uptake, weight stability, and dimensional behavior during play and storage.
Synthetic and Coated Leather Substitutes
PU-coated fabrics, PVC leather cloth, and microfiber-based synthetic leathers increasingly substituted for genuine leather in sports products. Although these materials fall under textile-based standards for some methods, they are routinely evaluated with the same gravimetric and airflow principles to enable direct comparison with genuine leather.
For all categories, laboratories generally require a minimum of three specimens per material condition, cut free of visible defects, creases, and brand markings, and conditioned to equilibrium in a standard atmosphere (typically 23 °C ± 2 °C and 50 % ± 5 % relative humidity per ISO 2419, or the atmosphere specified by the governing method) for at least 24 hours before testing. Specimen thickness is recorded per ISO 2589 as supporting data, since thickness correlates inversely with permeability.
Testing Items
- Water vapor permeability (WVTR), reported in mg/(cm²·h) or g/(m²·24h)
- Air permeability, reported in mm/s or cm³/(cm²·s) at a stated pressure differential
- Water vapor absorption and desorption (dynamic moisture buffering), reported in mass percent per ISO 17229
- Supporting measurements: thickness (ISO 2589), mass per unit area, and conditioning history
Testing Methods
Water Vapor Permeability – Permeability Cell Method (ISO 14268 / GB/T 4689.21)
A circular specimen is sealed, finished side oriented as specified, over a permeability cell or vessel containing a defined quantity of water. The assembly is mounted on a rotating carrier or exposed to controlled air circulation inside a conditioned chamber. Water vapor migrates through the leather and is carried away by the ambient air; the assembly is weighed at successive intervals, and the mass loss is plotted against time. The water vapor transmission rate is calculated from the slope of the linear portion of the curve divided by the test area, and the mean of all valid specimens is reported.
Water Vapor Transmission – Gravimetric Dish Method (ASTM E96/E96M)
The specimen is sealed across the mouth of a shallow dish filled either with water (wet-cup method, simulating a humid interior) or with desiccant (dry-cup method, providing a strong vapor gradient). The dish is weighed periodically in a controlled climate until a steady rate of mass change is established. This method is particularly suitable for coated leathers, multilayer laminates, and footwear constructions incorporating membranes, and the result is expressed as WVTR in g/(m²·24h).
Air Permeability – Pressure Differential Method (ISO 9237 / ASTM D737)
The conditioned specimen is clamped over a calibrated test head of known open area, and a defined pressure differential—commonly 100 Pa, with higher values such as 200 Pa or 500 Pa used for dense, thick, or heavily finished leathers—is applied across the material. The volumetric airflow passing through the specimen is measured with a flow meter, and the air permeability is calculated as flow rate divided by test area. Dense leathers that show negligible flow at standard pressure may be tested at elevated pressure differentials, which must be clearly stated in the report.
Conditioning and Specimen Preparation
All specimens are sampled per ISO 2418 from representative material zones, conditioned per ISO 2419 or the atmosphere required by the applicable standard, and allowed to reach moisture equilibrium before measurement. Because leather is hygroscopic and anisotropic, specimen orientation (grain side versus flesh side relative to the vapor or air stream), sampling position, and thickness are recorded, as these factors materially affect the reported result.
Applications
- Material selection and formulation development by tanneries, including evaluation of retanning, fatliquoring, and finishing systems
- Incoming quality control and supplier qualification for sporting goods brands, footwear manufacturers, and glove producers
- Verification against brand-specific or industry performance specifications for breathable upper and glove leathers
- Substantiation of comfort-related marketing claims such as "breathable," "moisture-managing," or "high-performance"
- Comparative benchmarking between genuine leather and synthetic or coated substitutes
- Failure analysis of products exhibiting sweat damage, odor, stiffness, coating delamination, or dimensional instability in service
FAQ
What level of breathability is considered acceptable for sports leather?
Acceptance limits are specification-dependent, but many footwear and glove material specifications reference water vapor permeability values in the range of 2 mg/(cm²·h) to 5 mg/(cm²·h) or higher for unlined, well-finished upper leathers. Heavily coated or laminated leathers naturally fall below these values, so the governing purchase specification should always be confirmed before testing.
Should I request water vapor permeability or air permeability?
Water vapor permeability correlates most closely with physiological comfort and perspiration management and is the primary index for sports gloves and footwear uppers. Air permeability is a faster screening indicator of convective porosity and is useful for process control and for comparing finishing systems. Many clients request both to obtain a complete breathability profile.
How many specimens are required?
A minimum of three specimens per material condition is required by the standards, while five specimens are recommended for heterogeneous natural leathers where grain structure varies across the hide. Additional material should be supplied to allow retesting if a specimen is damaged during clamping.
Do finishing and thickness affect the results?
Yes, significantly. Heavy pigment base coats and dense top coats can reduce water vapor permeability by half or more, and every increment in thickness lowers both vapor and air transmission. For this reason, finished production samples rather than crust leather should be tested whenever the goal is to qualify the final commercial material.
What sample size should be submitted to the laboratory?
A full swatch of at least 30 cm × 30 cm per material condition is recommended so the laboratory can cut specimens from representative positions and retain surplus material. Pre-cut discs or squares are also acceptable provided they meet the dimensional requirements of the selected test head.
Can synthetic leather and coated fabrics be tested under the same methods?
Yes. PU and PVC leather substitutes and microfiber materials are routinely evaluated using the same gravimetric vapor methods and airflow principles, with textile-based standards such as ISO 9237 and ASTM D737 applied where appropriate for air permeability determination.
What is the typical turnaround time?
Because conditioning alone requires at least 24 hours and gravimetric methods require several days of incremental weighing to reach steady-state transmission, a typical reporting turnaround is five to ten working days from receipt of conditioned samples, depending on the number of methods and material conditions requested.