Barrier testing is a key step in the development of products such as plastic films, packaging, technical textiles, and construction products, all of which must provide a high degree of protection against environmental exposure.
Water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) are the two barrier properties most often evaluated across different industries. In some cases, additional gas transmission rates may need to be determined, for example, if the material is exposed to a specific gas during the production process or end use. Similarly, water and grease resistance and air permeability can be important indicators of barrier performance in certain applications.
Standard methods for barrier testing
Table 1 provides an overview of commonly applied barrier testing methods and the types of materials each test can be used to evaluate. It may be possible to accommodate other sample types upon request, so do not hesitate to contact us if you need testing for matrices other than those listed.
Table 1: Selected barrier testing methods & standards
Test | Standard(s) | Suitable samples |
DIN 53122-1 ASTM E96 | Low-barrier polymeric films with WVTR > 1 g/m2/day. Options for paper and textiles are available. | |
ASTM F1249 ISO 15106-2 | Plastic films with WVTR > 0.005 g/m2/day. Options for paper, board, and packaging are available. | |
In-house method | High-barrier plastic and metallic films with WVTR > 0.000001 g/m2/day | |
ASTM D3985 ASTM F1927* ASTM F1307** | Plastic films with OTR > 0.05 cm3/m2/day. Options for paper, board, and packaging are available. | |
Carbon dioxide (CO2) transmission rate – infrared method | ASTM F2476-20 | Plastic films with CO2 transmission rate > 1 cm3/m2/day |
Hydrogen (H2) or chlorine gas transmission rate – differential pressure method | ISO 15105-1 | Polymeric films |
Nitrogen (N2) or helium (He) transmission rate – differential pressure method | ISO 15105-1 | Polymeric films with gas transmission rate > 0.05 cm3/m2/day x 0.1MPa |
Methane (CH4) transmission rate – differential pressure method | ISO 15105-1 ISO 15105-2*** | Polymeric films |
ISO 535 | Paper and board with a basis weight over 50 g/m2 | |
Grease resistance – KIT, turpentine, and palm oil methods | TAPPI T559 TAPPI 454 | Paper and board |
Air permeability – Bendtsen and Gurley methods | ISO 5636-3 ISO 5636-5 | Paper and board |
EN ISO 9237 | Textiles, fabrics, nonwovens |
* Standard used for tests performed in high-moisture conditions.
** Standard used for packaging
*** Standard used when analyzing fragile samples.
Formulating a barrier testing plan
The most appropriate barrier testing procedure for a given sample is chosen based on several variables, including the material’s intended application, the gases or liquids it should block, and the expected transmission or absorbance rates. Test conditions, including humidity and temperature, should reflect the material’s intended real-life use environment.
Gas transmission rate tests are most often performed on polymeric films or sheets during material development, but several methods can be modified to evaluate the barrier properties of paper, board, textiles, and finished packages. Sample dimensions should always be confirmed with the laboratory to ensure testing can be completed successfully. This is especially important with paper samples, as the so-called “edge-effect”, where gas passes past the edge of the sample rather than through it, may lead to an overestimation of the transmission rate.
The following sections contain examples of typical barrier testing projects, explaining the rationale behind method selection in each case.
Example 1: Food packaging
Barrier properties are crucial in the food industry, as protection from moisture and gases directly affects the shelf life of packaged foods. A typical testing procedure for finished plastic packaging includes the following tests:
WVTR measurement for packages (in-house method), performed at room temperature (23 °C) and 50% relative humidity (RH).
OTR measurement for packages (ASTM F1307), performed at room temperature and 0% RH or 50% RH.
If the product is marketed in countries with a hot and humid climate, testing should be performed at elevated conditions (often 38 °C and 90 % RH). Other temperature and humidity conditions are also available.
When paper or board packaging is tested instead of plastic, water and grease resistance are also relevant indicators of barrier performance. They are often evaluated with the Cobb water absorbance and KIT grease resistance tests.
Example 2: Construction materials
Construction materials typically require barrier testing when they are used in waterproofing or other insulating applications. In the EU, standard methods and acceptance criteria are specified separately for each product type in harmonized technical specifications, either in the form of harmonized standards or European Assessment Documents (EADs). These criteria must be met for the product to comply with the Construction Products Regulation and be eligible for the CE marking.
Examples of barrier tests typically required for different categories of construction products include the following:
Water vapor permeability of thermal insulating products (EN 12086)
Short-term (ISO 29767) and long-term water absorption (EN 12087) of thermal insulating products
Airflow resistance of acoustic materials (ISO 9053)
Water impermeability of waterproof material layers applied below ceramic tiling (EN 14891, Test A.7)
Watertightness of flexible sheets for waterproofing (EN 1928)
While not required by European technical specifications, the methane and carbon dioxide permeability of products offering protection against ground gases should be assessed according to ISO 15105-1 when such products are marketed in the UK. This recommendation is outlined in the British BS 8485 standard.
Example 3: Waterproof jacket
When optimizing the barrier properties of waterproof textiles, water and wind resistance should be balanced with breathability. In essence, the fabric should protect the wearer from the elements while simultaneously letting perspiration escape. The following are examples of testing methods used to verify that these properties meet the desired specifications:
Moisture transmission rate (WVTR) according to ASTM E96
Resistance to water penetration according to ISO 811
Air permeability according to ISO 9237
Measurlabs offers barrier testing with all the methods described above, and more. Do not hesitate to contact our experts for a quote tailored to your requirements.