While "resistance to water vapor transmission" conceptually refers to a material's ability to impede the passage of water vapor, the most common practical measurement used to quantify this property, especially in packaging, textiles, and building materials, is the Moisture Vapor Transmission Rate (MVTR). A lower MVTR signifies a higher resistance to water vapor transmission.
Understanding Water Vapor Transmission Measurement
The Moisture Vapor Transmission Rate (MVTR), also known as water vapor permeability or water vapor transmission (WVT) rate, quantifies the amount of water vapor that passes through a given area of a material over a specific period under controlled conditions of temperature and humidity. This rate is the primary metric for assessing a material's barrier properties against moisture.
Key Units of Measurement for MVTR
The units for MVTR reflect the mass of water vapor transmitted per unit area per unit time. The most widely adopted international and regional units are:
| Unit | Description
