
ASTM E96: Standard for Measuring the Water Vapor Transmission Rate of Materials
The ASTM E96 standard describes a standardized procedure for measuring the water vapor transmission rate (WVTR) of various materials. This method is essential in industries where the moisture resistance of materials is crucial, such as in construction, packaging, textiles, and medical devices. Accurate measurement and adherence to the ASTM E96 standard provide companies with a reliable foundation for evaluating the durability and moisture resistance of their products.
What is ASTM E96?
ASTM E96 is a testing method developed by ASTM International (formerly known as the American Society for Testing and Materials). This standard ensures that the water vapor transmission rate of materials is measured uniformly and precisely. The WVTR indicates how well a material allows moisture in the form of vapor to pass through. This property is vital in various industries, especially where products are exposed to moisture.
The ASTM E96 test is particularly relevant for materials like films, membranes, textiles, and building materials. Knowing a material’s WVTR helps companies choose the optimal materials for specific applications, such as regulating indoor humidity in construction or protecting products in packaging from moisture.
The Two Main Methods of ASTM E96
ASTM E96 offers two main methods, each suitable for different requirements and material properties:
Water Method:
In this method, a container with water is sealed with a material sample placed over it. The container is then placed in an environment with controlled humidity. The weight of the water is measured over a specified period to determine how much water vapor has passed through the material.
This method is particularly useful for materials used in humid environments and provides accurate insights into the vapor permeability of products that act as moisture barriers.
Desiccant Method:
The Desiccant Method uses a desiccant placed in a container covered with the material sample. The desiccant absorbs moisture that passes through the material, and its weight is measured over time.
This method is especially suitable for materials used in drier environments and provides information on moisture absorption in dry conditions.
Applications of the ASTM E96 Standard
ASTM E96 is widely used in several industries. Here are some of its main applications:
Construction Industry
In construction, moisture regulation is crucial for the durability and structural integrity of buildings. ASTM E96-certified materials are often used for insulation and moisture control, such as in barriers to prevent mold growth and enhance energy efficiency.
Medical Devices
In medical and pharmaceutical applications, moisture control is often necessary to maintain the sterility and shelf life of packaging and products. The ASTM E96 standard helps ensure the selection of materials for packaging that can protect against moisture exposure.
Textile Industry
In textile manufacturing, especially in outdoor clothing, water vapor transmission is essential for comfort and weather resistance. ASTM E96 ensures that textiles regulate moisture while remaining breathable.
Packaging Industry
The packaging industry uses ASTM E96 to select materials that protect sensitive products from moisture. Food packaging, pharmaceuticals, and electronics often rely on moisture barriers to preserve quality and safety.
ASTM E96-Certified Machines
Several machines have been developed to perform this test and meet ASTM E96 requirements. Here are five machines designed for this standard:
- With GraviTest the determination of water vapour transmission rates of polymeric films and other sheet materials by gravimetric method becomes mere child’s play.
- The new Automatic Gravimetric WVTR Tester GINTRONIC GraviTest 6250 comes with a 0.01mg balance as a standard feature. The 0.01 mg balance makes WVTR measurements of low perm materials 2-3 times faster than the previous generation systems.
- The same instrument like GINTRONIC GraviTest 6300/6400, but with 10 sample places with 30cm2 / 28,3cm2. Conforms to ASTM E96, JIS L1099 A1+A2 and many others.