HZO Material Testing: Water Vapor Transmission

The superior barrier properties of the Parylene-based solutions developed by HZO provide excellent levels of corrosion resistance and prevention from a wide range of environmental factors. Conditions like water and liquid immersion, high humidity, salt spray and other corrosive vapors are known killers of electronics, and occur in every day situations—damaging and destroying electronics ranging from personal smartphones to industrial sensors.

We’ve talked a lot in this blog about different testing methods, how they are conducted, and the unique requirements that various industries have for defining and measuring results for water resistant electronics. To date, most of the tests we’ve covered have primarily been those that are conducted on complete assemblies and devices in order to ensure extended survival and performance.

In addition to the physical testing of product survival, it’s also critical to have an understanding of both the performance and limitations of the coating or material providing the protection.



One of the very important features of the HZO thin film material that gets analyzed is its water vapor transmission rate (WVTR), also known as moisture vapor transmission rate (MVTR).

There are a wide array of industries that look to WVTR to help control and mitigate the usability, risk and damage that moisture can have on products ranging from the breathability of sports apparel to the shelf life of packaged goods.

Simply put, WVTR is the speed and volume at which even the most minuscule amounts of water vapor will penetrate a barrier, film, coating or other substance.

The importance of the measurement in regards to protecting electronics is important for obvious reasons, and on the scale of utility, the lower the value of WVTR, the better and longer a device should perform when exposed to wet conditions and environments.

This is especially important when it comes to protecting electronics, because over time most materials will allow water or liquid through a surface, via tiny pinholes, inconsistencies or other material imperfections.


The testing itself is typically performed in a chamber using relative humidity conditions as a measurement, and as always, in order to get accurate readings, the temperature and humidity conditions are carefully controlled and monitored to ensure accurate results.

The test itself is calculated in g/100 in2/24hrs, and results conclude HZO material at .23g/m2/24hrs. In other words, over an extended period period of time, only a negligible amount of moisture ever penetrates the HZO protective film.

In the case of HZO Parylene solutions, the greater the thickness of the material the better the WVTR, and when it comes to testing, Parylene is one of the top performing materials available as a barrier coating solution.

Needless to say there are a lot of methods for analyzing, understanding and comparing material features for protecting electronics, and over the coming months we’ll be sharing more details about what they are and why they matter to creating solutions that help electronics perform reliably in more conditions and last longer.

In the meantime, contact us to learn more about how HZO might be able to make a positive impact in your organization.

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