Abstract

The Water Vapor Transmission Rate (WVTR) is a critical parameter for evaluating the barrier properties of thin sheet 

materials used in packaging, textiles, and medical applications. ISO 2528 provides a standardized gravimetric method for

 determining WVTR, ensuring consistency and reliability in measurements. This article discusses the principles, 

procedures, and significance of the gravimetric method as per ISO 2528, along with its applications and limitations.

1. Introduction

Thin sheet materials, such as plastic films, papers, and laminates, are widely used in industries where moisture barrier

 properties are essential. WVTR measures the amount of water vapor that permeates through a material over a specified 

time and area under controlled conditions. ISO 2528 specifies the gravimetric (weight-based) method for WVTR

 determination, offering a straightforward and reproducible approach.

Testing instruments:WVTR-C6 Water Vapor Permeability Tester

2. Principle of the Gravimetric Method

The gravimetric method involves exposing a test specimen to a controlled humidity gradient and measuring the 

weight change due to water vapor transmission. The specimen is sealed over a desiccant (or water) in a test dish,

 creating a dry (or wet) environment on one side and a humid (or dry) environment on the other. The weight gain 

(or loss) over time is recorded to calculate WVTR.

3. Experimental Procedure (ISO 2528)

Sample Preparation: Cut specimens to fit the test dish, ensuring no defects.

Test Setup: Place a desiccant (e.g., anhydrous calcium chloride) in the dish and seal the specimen over the opening.

Conditioning: Place the dish in a controlled environment (e.g., 23°C, 50% RH or as specified).

Weighing: Measure the dish weight at regular intervals until steady-state transmission is achieved.

4. Applications

Packaging: Assessing moisture protection for food, pharmaceuticals.

Textiles: Evaluating breathability of waterproof fabrics.

Medical: Testing barrier properties of wound dressings.

5. Conclusion

ISO 2528’s gravimetric method provides a reliable and standardized approach for WVTR determination, essential 

for material development and quality control. Proper adherence to test conditions ensures accurate and comparable

 results across industries.