"Breathability is not just a feature; it's a necessity for outdoor apparel. It's the difference between comfort and discomfort, between enjoying the outdoors and enduring it." - Allen Chen, R&D Manager of FlyingTex.
If you design, manufacture, or sell outdoor wear, you're likely already familiar with microporous membranes. For those new to the field, understanding the difference between microporous and hydrophilic membranes might still be a bit puzzling. Whatever the case, in this article, we will cover the basics for beginners, delve into advanced details about different testing standards for our knowledgeable followers, and finally introduce you to the latest developments from Taiwan, which you'll definitely want to consider for your next outerwear collection. So, let’s get to it~
A microporous (also known as hydrophobic) membrane is an ultra-thin film with a spongy structure made up of interconnected tiny pores. These pores usually range from 0.03 μm to 10 μm in diameter. They are small enough to prevent water droplets from passing through but large enough to allow water vapor to escape. This feature significantly improves the waterproofness and breathability of fabrics, making them ideal for outdoor and activewear.
Microporous membranes are made from polymers such as PTFE and polyurethane (PU) and are typically laminated between an outer, durable fabric and an inner, soft lining. These membranes are lightweight, usually weighing between 10–20 g/m2, and are designed for durability, offering resistance to damage from laundering, chemicals, and UV exposure. Microporous fabrics often include a water-repellent finish to further enhance their performance and prevent pores from becoming blocked.
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Two numbers you'll frequently see on laminated fabrics are W/P (Waterproofness) and MVP (Moisture Vapour Permeability). Despite microporous fabrics being highly regarded for their breathability, you might find yourself puzzled as to why the MVP numbers (aka breathability ratings) for fabrics with microporous membranes tend to be lower. This is because of the different testing methods used for fabrics with microporous membranes versus those with hydrophilic membranes.
Microporous membranes are tested using the ‘upright cup test’, while the ‘inverted cup test’ is being used for the hydrophilic membranes. The names of the tests are pretty much self-explanatory.
The upright cup test, known as JIS L 1099 A1 or ASTM E96 B, involves placing either calcium chloride (for JIS L 1099 A1) or water (for ASTM E96 B) in a cup. For the JIS L 1099 A1 method, a fabric piece is stretched across the top of the cup, with its membrane side facing upwards, and then placed in a controlled environment maintained at 40℃ and 90% humidity, conditions similar to our bodies when we sweat.
On the other hand, the ASTM E96 B method involves placing the fabric over the cup with the membrane side facing downwards, and the cup is then set in an environment with a temperature of 23℃ and 50% humidity, reflecting typical outdoor conditions. After an hour, the weight of the cup is measured to determine the amount of water that has passed through the fabric. This measurement is used to calculate the moisture transmission rate, showing how many grams of moisture can pass through a square meter of the fabric in 24 hours.
The inverted cup test also has two methods: JIS L 1099 B1 and ASTM E96 BW. In the JIS L 1099 B1 method, potassium acetate (a desiccant) is placed inside a cup. The fabric being tested is then laid over this cup, with the membrane side facing out. The cup is inverted and placed into a water-filled pan.
In contrast, the ASTM E96 BW method involves securing the fabric over a water-filled cup with the membrane side facing inward. This cup is then turned upside down and placed in a controlled environment, maintained at a temperature of 23℃ and 50% humidity, reflecting typical outdoor conditions. After 15 minutes, the cup's weight is measured to check the amount of water that has passed through the fabric. This measurement is used to calculate the moisture transmission rate, indicating how many grams of moisture can pass through a square meter of the fabric in 24 hours.
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At FlyingTex, we collaborate with our partner, Xpore, to incorporate their ultra-thin microporous membranes made from polyolefin (PO) into our fabrics. In addition to all the functional benefits already mentioned, these membranes are free from PFCs and solvents. Our latest development in the Xpore collection is the new LiteTech 2.5-layer fabrics. By using 40D recycled nylon yarn and eliminating the need for a third layer, these fabrics are lightweight yet still offer robust protection. Coupled with mechanical stretch, they provide comfort and adaptability, perfect for active lifestyles in any setting, from outdoor adventures to urban exploration. To check more Xpore fabric features visit our Fabric Database.
It has been over 50 years now since the microporous membrane was first used in garments, and the technology has advanced a lot in terms of functionality and environmental impact. Our journey with microporous membranes reflects our dedication to creating products that are not just superior in quality but also kinder to our planet. Reach out to us at [email protected] to learn how these high-functional and sustainable fabrics can enhance your next outdoor collection!
