Water vapor permeability testing service

Water Vapor Permeability Testing Service – Comprehensive Evaluation of Moisture Barrier Performance for Packaging, Construction, Textiles, and Medical Devices

As an ISO/IEC 17025 accredited independent testing laboratory, we provide specialised water vapor permeability (WVP) and water vapor transmission rate (WVTR) testing services to manufacturers, suppliers, and quality assurance teams across the packaging, construction, textile, pharmaceutical, medical device, automotive, and electronics sectors. Water vapor permeability – the rate at which water vapor passes through a material under controlled conditions of temperature and humidity – is a critical performance parameter for products that must protect against moisture ingress or egress. In Chile's diverse climate, from the hyper‑arid Atacama Desert to the humid coastal regions and the rainy south, the moisture barrier performance of materials directly affects product shelf life, building durability, occupant comfort, and patient safety. Our test protocols measure the steady‑state WVTR under a range of environmental conditions (temperature and relative humidity differentials) using standardised methods, including the gravimetric (dry cup and wet cup) method, the infrared sensor method, and the electrolytic sensor method. All procedures are aligned with ISO, ASTM, and NCh standards, including ISO 12572 (Hygrothermal performance of building materials – Determination of water vapour transmission properties), ASTM E96 (Water Vapor Transmission of Materials), ASTM F1249 (Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated Infrared Sensor), ISO 15106‑1 (Plastics – Film and sheeting – Determination of water vapour transmission rate – Part 1: Humidity sensor method), ASTM D1653 (Water Vapor Transmission of Organic Coating Films), and NCh 2073 (Building materials – Hygrothermal properties). Our reports are recognised by the Standards Council of Canada (SCC), the Ministry of Public Works (MOP), the Superintendency of Electricity and Fuels (SEC), the Institute of Public Health (ISP) for medical devices, and leading Chilean construction, packaging, and pharmaceutical companies for product certification, quality assurance, and regulatory compliance.

Materials and Products We Regularly Test

Our water vapor permeability testing laboratories accommodate a wide range of materials, component forms, and finished products. Typical test articles include:

• Flexible packaging films – polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA), ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), and metalised films
• Rigid packaging materials – plastic containers, bottles, blister packs, and closures
• Construction materials – vapour barriers, building wraps, insulation materials, gypsum boards, and waterproofing membranes
• Textiles and nonwovens – breathable fabrics, protective clothing, geotextiles, and roofing membranes
• Medical device packaging – sterile barrier systems, pouches, and thermoformed trays
• Coatings, paints and varnishes – architectural coatings, industrial finishes, and wood coatings
• Paper and paperboard – packaging papers, labels, and corrugated board
• Composite materials – multi‑layer laminates, metal‑polymer composites, and structural insulated panels
• Adhesives and sealants – for assessing their moisture barrier properties
• Elastomers and rubbers – gaskets, seals, and grommets

Gravimetric Method – Dry Cup and Wet Cup Testing (ASTM E96 / ISO 12572)

• Dry cup method (desiccant method) – ASTM E96 / ISO 12572 Method A – We place a desiccant (anhydrous calcium chloride or silica gel) inside a test cup, and seal the test specimen (membrane, film, or sheet) over the cup's opening. The assembly is weighed and placed in a controlled environment chamber at a specified temperature (typically 23 °C, 38 °C, or 50 °C) and relative humidity (typically 50 % RH, 90 % RH, or 100 % RH). The water vapor that passes through the specimen is absorbed by the desiccant, and the weight gain of the cup assembly is measured at regular intervals (e.g., every 24 hours) until a steady‑state rate is achieved (typically 3‑5 consecutive measurements with a linear weight gain). The water vapor transmission rate (WVTR) is calculated from the steady‑state slope of the weight gain versus time curve. The method is suitable for materials with low to moderate permeability, and is the most widely used method in the packaging and construction industries in Chile.
• Wet cup method (water method) – ASTM E96 / ISO 12572 Method B – We fill the test cup with distilled water (or a saturated salt solution to control humidity), and seal the test specimen over the cup's opening. The assembly is weighed and placed in a controlled environment with a lower relative humidity than that inside the cup. The water vapor that passes through the specimen is lost to the environment, and the weight loss of the cup assembly is measured at regular intervals. The WVTR is calculated from the steady‑state slope of the weight loss versus time curve. This method is used for materials that are permeable to water vapor, and is often used for building materials and textiles.
• Modified wet cup method (for high‑permeability materials) – For materials with high WVTR (e.g., textiles, nonwovens), we use a modified wet cup method with a shorter test duration and a higher frequency of weighing to capture the rapid transmission rate.
• Temperature and humidity control – for simulating Chilean climatic conditions – We perform the gravimetric tests at a range of temperatures (5 °C, 23 °C, 38 °C, 50 °C) and humidity levels (30 % RH, 50 % RH, 75 % RH, 90 % RH) to simulate the different climatic regions of Chile – from the dry north (Atacama Desert) to the humid south (Valdivia, Puerto Montt). The testing is performed in accordance with ISO 12572 and NCh 2073.
• Specimen preparation and conditioning – ASTM E96 / ISO 12572 – We condition the test specimens at the specified temperature and humidity for a minimum of 24 hours (or until constant mass) before the test, to ensure that the material has reached equilibrium with the test environment. The thickness of the specimen is measured at multiple points, and the average thickness is used in the permeability calculation.

Infrared Sensor Method – ASTM F1249 / ISO 15106‑2

• Principle of the method – ASTM F1249 / ISO 15106‑2 – We use a commercially available water vapor permeation analyser (e.g., Mocon Permatran) that operates on the principle of modulated infrared (IR) detection. The test specimen is mounted in a test cell, dividing it into two chambers: the upper chamber (where the water vapor is generated) and the lower chamber (where the transmitted water vapor is detected). The upper chamber is maintained at a specified temperature and relative humidity (typically 23 °C / 50 % RH, 38 °C / 90 % RH, or 50 °C / 50 % RH). The lower chamber is purged with dry nitrogen, which carries the transmitted water vapor to an IR detector. The detector measures the concentration of water vapor in the carrier gas, and the WVTR is calculated from the steady‑state concentration. The method is highly sensitive, accurate, and can measure WVTR down to 0.001 g/m²·day. It is suitable for high‑barrier materials (e.g., metalised films, EVOH, and multi‑layer laminates) used in food and pharmaceutical packaging.
• Temperature and humidity control – for simulating different climatic conditions – We perform the IR method at a range of temperatures and humidities to simulate the storage and transport conditions of products in Chile.
• Specimen conditioning and mounting – ASTM F1249 / ISO 15106‑2 – We condition the specimens at the test conditions for a minimum of 24 hours before testing. The specimens are carefully mounted in the test cell to prevent edge leakage and ensure a uniform seal.
• Calibration and verification – ASTM F1249 / ISO 15106‑2 – We calibrate the IR analyser using certified reference films with known WVTR values, and we include reference films in each test run to verify the instrument performance.

Electrolytic Sensor Method – ISO 15106‑3 / ASTM D7194

• Principle of the method – ISO 15106‑3 / ASTM D7194 – We use an electrolytic sensor (phosphorous pentoxide) to measure the water vapor concentration in a carrier gas. The test specimen is mounted in a test cell, and the upper chamber is maintained at a specified temperature and humidity. The lower chamber is purged with dry nitrogen, which carries the transmitted water vapor to the electrolytic sensor. The water vapor is absorbed by the P₂O₅ coating, and an electrical current is generated, proportional to the water vapor concentration. The WVTR is calculated from the steady‑state current. The method is suitable for very low WVTR measurements (down to 0.0005 g/m²·day) and is used for ultra‑high barrier films.

Specific Applications – Packaging, Construction, Medical Devices and Textiles

• Packaging materials – food and pharmaceutical packaging – We test flexible and rigid packaging materials for their WVTR to ensure that they provide adequate protection against moisture ingress for dry foods, pharmaceuticals, and sensitive electronic components. For Chilean food exporters (e.g., fresh fruit, wine, seafood), a low WVTR is essential for maintaining product quality and shelf life during transport to international markets.
• Construction materials – vapour barriers and building wraps – We test vapour barriers, building wraps, and insulation materials to ensure that they meet the requirements of the Chilean building code (Ordenanza General de Urbanismo y Construcciones – OGUC) and the NCh 2073 standard for hygrothermal performance. A low WVTR is essential for preventing condensation within walls and roofs, particularly in the humid southern regions of Chile.
• Medical device packaging – sterile barrier systems – We test medical device packaging (pouches, trays, and lids) to ensure that they provide an adequate moisture barrier to protect sterile devices during storage and transport. The test is performed in accordance with ISO 11607 and ASTM F1249, and is required for the registration of medical devices with the Institute of Public Health (ISP) in Chile.
• Textiles and breathable fabrics – protective clothing – We test breathable fabrics and protective clothing materials to measure their WVTR, which is a measure of their comfort and breathability. A high WVTR is desirable for activewear and protective garments that must allow perspiration to escape.
• Coatings, paints and varnishes – We test architectural coatings and industrial finishes to determine their resistance to water vapor transmission, which is important for preventing blistering and adhesion loss in humid environments.

Simulation of Extreme Climatic Conditions – Atacama Desert, Patagonia and Coastal Regions

• High‑temperature and high‑humidity conditioning – for simulating coastal and tropical conditions – We perform WVTR testing at 38 °C and 90 % RH to simulate the conditions of the coastal regions of Chile (e.g., Valparaíso, Concepción) and the humid southern regions.
• Low‑temperature conditioning – for simulating the Patagonia and the Andes – We perform WVTR testing at 5 °C and 10 °C to simulate the conditions of the Patagonia and the high‑altitude regions.
• Dry and arid conditioning – for simulating the Atacama Desert – We perform WVTR testing at 50 °C and 20 % RH to simulate the conditions of the Atacama Desert, where the moisture content of the air is extremely low.
• Thermal cycling and ageing – for simulating diurnal and seasonal temperature variations – We expose the specimens to thermal cycles (e.g., -10 °C to +50 °C) and then perform the WVTR test, to assess the effect of temperature variations on the moisture barrier performance.

Data Analysis and Interpretation – Quantifying Moisture Barrier Performance

• Water vapor transmission rate (WVTR) – in g/m²·day or g/m²·24h – The WVTR is the primary output of the test. A low WVTR (e.g., < 1 g/m²·day) indicates a good moisture barrier; a high WVTR (e.g., > 100 g/m²·day) indicates a breathable material. The WVTR is reported at the specified temperature and humidity.
• Water vapor permeability (WVP) – in g·mm/m²·day·kPa or g·m/m²·s·Pa – The WVP is the WVTR corrected for the material thickness and the vapour pressure difference. It is a material property that is independent of the test conditions.
• Permeance – in g/m²·day·kPa or perms – The permeance is the WVTR divided by the vapour pressure difference. It is a measure of the resistance to water vapor flow through the material.
• Water vapor resistance (WVR) – in m²·day·kPa/g or m²·s·Pa/g – The WVR is the inverse of the permeance, and is a measure of the resistance to water vapor flow.
• Statistical analysis – for batch‑to‑batch consistency – For multiple specimens, we report the mean WVTR, the standard deviation, and the coefficient of variation (CV). A CV < 10 % is considered excellent.

Regulatory Compliance and Product Certification – Supporting Chilean and International Standards

Our water vapor permeability testing services are performed in accordance with the most widely used international and Chilean standards. The most commonly requested include:

• ASTM E96 – Standard Test Methods for Water Vapor Transmission of Materials – the primary standard for WVTR testing in North America
• ISO 12572 – Hygrothermal performance of building materials – Determination of water vapour transmission properties – the international standard for building materials
• ASTM F1249 – Standard Test Method for Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated Infrared Sensor – the standard for IR sensor WVTR testing
• ISO 15106‑1 – Plastics – Film and sheeting – Determination of water vapour transmission rate – Part 1: Humidity sensor method – the international standard for IR sensor WVTR testing
• ISO 15106‑2 – Plastics – Film and sheeting – Determination of water vapour transmission rate – Part 2: Infrared detector method – the international standard for IR sensor WVTR testing
• ASTM D1653 – Standard Test Methods for Water Vapor Transmission of Organic Coating Films – for paints and coatings
• ISO 11607 – Packaging for terminally sterilised medical devices – for medical device packaging
• ISO 15496 – Textiles – Determination of water vapour transmission rate of textiles – for textiles
• NCh 2073 – Building materials – Hygrothermal properties – the Chilean standard for building materials
• Norma Técnica de Construcción – OGUC – Chilean Building Code – for construction materials
• ASTM D7194 – Standard Test Method for Water Vapor Transmission Rate of Flexible Barrier Materials using an Electrolytic Sensor – for high‑barrier materials

Interpretation of Results and Acceptance Criteria

• WVTR (g/m²·day) at 23 °C / 50 % RH – < 1 g/m²·day is excellent for high‑barrier packaging ; 1‑10 g/m²·day is acceptable for standard packaging ; > 10 g/m²·day is insufficient for moisture‑sensitive products.
• WVTR (g/m²·day) at 38 °C / 90 % RH – < 5 g/m²·day is excellent for tropical and coastal applications ; 5‑20 g/m²·day is acceptable ; > 20 g/m²·day is insufficient.
• Permeance (perms) – < 0.1 perms is excellent for vapour barriers ; 0.1‑1.0 perms is acceptable ; > 1.0 perms is insufficient for vapour barriers (but desirable for breathable materials).
• WVP (g·mm/m²·day·kPa) – The WVP is a material property that is independent of thickness. A low WVP indicates a good moisture barrier.
• Statistics and uncertainties – For each series of tests (at least 5 specimens), we provide the mean, standard deviation, and coefficient of variation (CV) for the WVTR. A CV < 10 % is considered excellent.

Advantages of Our Service for the Chilean Market

• ISO/IEC 17025 accreditation – guaranteeing the reliability, traceability, and international acceptance of our results.
• Bilingual reports (Spanish/English) – to facilitate submissions to Chilean authorities and international partners.
• Simulation of climatic conditions – our tests integrate the effects of high temperatures (Atacama Desert), low temperatures (Patagonia and the Andes), and high humidity (coastal and southern regions).
• Support for regulatory compliance – our reports are directly usable for product certification, building code compliance, and medical device registration with the ISP.
• Experience in packaging, construction, medical devices and textiles – our laboratory has extensive experience in the key sectors of the Chilean economy.
• Adapted turnaround times – we understand the logistical and commercial constraints of the Chilean market and are committed to delivering results within competitive timeframes.

Conclusion

Water vapor permeability testing is a fundamental tool for guaranteeing the moisture barrier performance of materials and products in the diverse climatic conditions of Chile. Our testing services, accredited under ISO/IEC 17025 and compliant with international standards and Chilean regulations (NCh, OGUC, ISP), allow you to validate the moisture barrier performance of your materials, optimise your selection, and ensure regulatory compliance. Whether you are a manufacturer, importer, contractor, engineer, or quality assurance professional, we accompany you in the mastery of water vapor permeability testing, from initial testing to final certification.