Facts about membrane clothing

Vladimír Bureš 19.11.2023

Nanomembrane may not be a REVOLUTION... But it is definitely an EVOLUTION.

Watch the video where we compared vapor permeability, or "breathing" away from the body.

Layering clothes.

We go outdoors dressed in multiple layers of functional clothing. It works as it should, but only if we put the whole thing together properly. If I throw on a merino wool shirt, put on an old and worn out knit sweater, and a gorac jacket on top, I can't expect it to do the trick. Even though the manufacturer says so on the label...

What are the layers for?

If I don't layer, I risk hypothermia or overheating. Apart from the risk of illness (that comes later), the body tries to cope with these conditions on its own. It will expend unnecessary energy to achieve equilibrium, making us tired sooner. And with that comes a mistake, a stumble, a fall...
On a mountain hike, I wear a thermo shirt as my 1st layer on my body. What is it? Simply tighter underwear whose job is to quickly transfer moisture away from the body to the next layer. 2nd layer, like a fleece sweatshirt. It has a similar function, but it's more insulating, it adds warmth. 3rd layer, it's already a barrier, it prevents heat loss. The body generates it during exertion, but the wind steals it, the snow and rain cool me down. When the cloths work, the water vapor generated by sweating is let out, preventing the body from cooling down due to the moisture and drying it out.

Membrane clothing as a top layer.

What are membranes and what can they do?

Simply put, manufacturing-intensive technical films with very specific properties. Marketed as 3 (sometimes 2 and 2.5 L) ply laminates, top fabric/membrane/lining. All membranes on the market will stand up to the rigors of the movement. However, if it's mountaineering and strenuous hiking, just more climbing, heavier pack, worse weather conditions, you'll see the differences for yourself. These fabrics won't blow in the wind, shouldn't get wet easily and instead should breathe outwards away from the body. In short, it's a non-pro-mattress. But let's be down to earth... Nothing works 100%. You can't, we're all different. Still, let's give the membrane a chance to show what it can do. That it won't waterproof or leak? A regular plastic raincoat can do that. What a raincoat can't do is provide vapour permeability. For completeness, we also have fabric with a coating, with an impermeable film, or siliconized. While it is cheaper compared to membranes, it will keep the moisture on the inside and not let it in. It is therefore unsuitable for clothing. So it's not until the membranes that the comfort of the clothes is taken much further.

What are the types of membranes?

Membranes from a range of manufacturers in the USA, Europe and Asia are divided into microporous and hydrophilic. A microporous membrane contains a large number of pores through which a drop of water cannot penetrate, but water vapour can. The advantage of this system is a decent vapour permeability, but on the other hand, the pores are usually clogged. Manufacturers solve this problem by coating the fibres with a PUR film or wrapping them with a thin layer of fluorocarbon (since 2020, the environmentally unfriendly C8 has been banned). This prevents dirt from adhering to the substrate. Membranes do not have hydrophilic pores. Moisture reaches the membrane and is drawn out by a chemical reaction to the surface where it evaporates. They have a much lower vapour permeability but a higher water column.

Nanofibre technology.

PTFE is not used here. The nanomembrane is not microporous either. It does not contain pores, but fibres. After years of research at TUL (Technical University of Liberec), the team around Ing. Roman Knížek completed the work, the project was pushed to the finish line by NANOMEMBRANE (Svitap), i.e. to mass production. Thanks to Lukáš Heřmanský (who represented the Czech Republic at the 2002 Olympic Games in Salt Lake City in Nordic combined) and his athlete's soul, these fabrics have created a new dimension of membrane clothing. His company possesses unique technology and know-how in the field of lamination. This makes its materials significantly different from the competition, especially in their ability to wick sweat away from the body. The fabrics or knits used for the production of laminates are made of synthetic (polyester, polyamide, etc.) as well as natural materials (wool, cotton, silk). NANOMEMBRANE also owns several patents and utility models in the areas of production, lamination and surface treatments. All product lines undergo very demanding tests not only in the company itself, but also in independent institutions such as the Technical University of Liberec or the German laboratory Hohenstein Institute. NANOMEMBRANE is the first company in the world to industrially produce a nanofibre membrane with a fibre diameter below 150 nm, with production in the Czech Republic. Thanks to its unique nanofibre structure with a fibre diameter of up to 150 nm, the nanofibre NANOMEMBRANE membrane has 20,000,000 more pores per 1 cm2 than microporous membranes. The patented Hydrophobic Extreme treatment (hydrophobic and oil-phobic) means that each individual fibre is coated with a thin layer of nanoparticles. This achieves the so-called self-cleaning effect that e.g. lotus leaves have. In contrast to conventional hydrophobic or oleophobic treatments, the interfibre pores are not blocked and thus the moisture wicking away from the skin of the body through the textile is not impaired. All fabrics or knits that are laminated with NANOMEMBRANE nanofibre membrane are factory-applied with Hydrophobic Extreme treatment.

Nanofibers are included in our textile yardage. They are referred to as the fabrics of the 3rd millennium and are set to revolutionise dressing. The nanofibers are loosely stacked in the fabric. They allow air to pass through, but water does not flow. Nanofibers can replace other, older, membranes. In particular, they outperform them in vapour permeability, which is key to wearing comfort. Nanofibre membranes are softer and lighter.

Faramugo is the first in the world to make outdoor clothing with a nano-membrane.

In Faramugo we work with Czech Nanomembrane materials. This has been the case since the day the university research was transferred into practice, i.e. since the beginning of 2015. That's when Nanomembrane approached us with an interest in cooperation and provided us with the first meters of nanomembrane fabric. Basically still a kind of "self-made" production on the knee. Nevertheless, the jacket from this test material has travelled with me a lot, I still use it occasionally. More here . In 2016, Outdoor Research tested nanomembrane fabrics in the USA. Today, The North Face in the US is also sewing nanomembrane clothing. But only we at Faramug can say that we are truly the first in the world to market nanomembrane outdoor clothing. NANOMEBRANE MAY NOT BE A REVOLUTION, BUT IT'S DEFINITELY AN EVOLUTION!

Benefits for you?

Nanomembrane "breathes" much better, it has extreme vapour permeability. You can press such a jacket into a backpack without it automatically delaminating (separating layers) after some time. The fabric is very soft and airy. The nano-membrane allows lamination with stretch fabric.

Key features of membrane fabrics.

Unfortunately, people are under the misconception that vapor permeability and breathability are the same thing. It is not. Even companies in the outdoor market misstate this. It's very common in the Czech Republic, due to a mistranslation from English. Whether the aim is to deceive, ignorance or just a feeling that everything is simpler this way.... Unfortunately, in the market, marketing is often more important than the truth.

Breathability or windproofness.

We need the top layer to protect us from the wind. The jacket must be waterproof! A membrane jacket will do this, as will a chamois jacket. The lower layers are both breathable and vapour permeable. The top layer is always waterproof. Breathability is given in units of l/m2/s and anything below 10 is 100% windproof. Some materials on the market have a large margin here.

Water resistance or water column.

And also hydrostatic resistance. Not waterproof. This property is the second value monitored for membrane clothing. It is the height of the water column (imagine a glass cylinder, full of water and pressed against the fabric) that the fabric can no longer handle and lets the water in. So we can do outdoor activities in a membrane jacket in wind or rain. What about the market? In Europe, the standard (what doesn't it apply to, right?) is ISO 811, according to which a material is waterproof if it can withstand a pressure of 1.3 m column of water. Is that enough? No. Kneel down in wet grass and you'll exert up to 15 m of pressure. Or compress the fabric with a heavier shoulder pack and you're at similar numbers. Falling into the snow will push your clothes to the limit of what they can handle. So logically better to choose a fabric with a higher water column. But do such borderline situations commonly occur in practice? Practically no, if they do, it's only short-term. Occasionally, you will see pressure values of up to 100 m water column, i.e. 100,000 mm, on the market. But can the top material withstand this? No, it will crack. So in practice, you can't even test such resistance, and in the open air, such quoted values serve you no purpose. What is enough? 10,000 vs for lightweight clothing, like running or skiing. And 20,000 vs for the mountains, which is the usual value.

Water repellency.

What is it? It's the various water-repellent treatments. The treatment is applied at the factory, called HYDROPHOBIC EXTREME. And restored by you, with various sprays. The water repellency is simulated by raining for 20 seconds to see how many drops seep through. St. 5 is the maximum. The treatment can also repel oils, dirt... But in the context of the ecological campaign, rather little. It used to be more, but the materials can no longer be manufactured. It's all about oleophobicity, i.e. non-staining, max. st. 8. This is achieved by surface tension, as low as possible. Dirt is then difficult to adhere to and can be easily removed. The treatments do not last forever, they lose their effectiveness over time through washing, wear and tear, for example backpack straps.

Vapor permeability.

Not breathability! A vapour permeable garment is one that does not prevent water vapour from moving out, away from the body. In a T-shirt, a sweatshirt, but also in a jacket. Vapour permeability therefore means how the fabric can cope with the moisture produced by the body during sport. And that's outwards, into the surrounding air. This important and expected ability of membrane clothing is measured in Ret or MVTR units. MVTR is in g/m2/24 h. The more the better. Ret, in Pa.m2/W, is exactly the opposite, where less is more. And it is far more objective. MVTR does not take temperature and humidity into account, so the data is not true. Ret evaluates, according to ISO 11092, the energy that is developed to evaporate a specific amount of water at a given temperature and humidity. Obviously, lower Ret is better for us, i.e. less energy is required.
And what Ret (or MVTR) can we be happy with for our clothes? In the outdoor market it is stated that what is below Ret 6 (i.e. very good) corresponds to an MVTR of 20,000 g/m2 in 24 hours. Is that enough or not enough? Humans naturally sweat even at complete rest. When moving around town, we make do with an MVTR of 1,500. For an intensive march around the lake we have a reserve. But if we put on a backpack and head uphill, we'll be at the limit. We'll easily get to 30,000 when running, and exceed 40,000 at higher loads in the mountains.

What to watch out for that the average user doesn't know or realize?

The numbers are nice, but basically useless. The values indicate the vapour permeability of 3L of fabric. The garment has pockets, printing, reinforcement, seams. There's no vapour permeability listed here, nor can it be. The fabric is also important, both the top fabric and the lining. If it severely degrades the vapour permeability, the membrane won't save it. And we want the fabric to be strong so that the jacket can withstand years of use. Or excellent abrasion resistance will reduce the waterproofing. The more you have of the various features mentioned above (pockets, seams, printing), the more you will have reduced vapor wicking.
As you can see, it's all about trade-offs. The same is true for vapor permeability and water resistance. They are opposites for something. Something is better, you have to forgive the other, it's inferior. And it's clear that the vapour permeability is rapidly reduced in the rain, when the vapour has nowhere to go and we need to be dry the most.

Can nanomembrane clothing compete with Gore-tex?

Nano-membrane clothing is becoming an increasingly popular alternative to traditional Gore-Tex. And sure, both technologies have their advantages and disadvantages.
Gore-Tex is a hydrophilic membrane with pores smaller than a drop of water but larger than a molecule of water vapor. This allows moisture to wick away from the body while preventing water from seeping in. Nanomembrane clothing works similarly, but instead of pores it has fibrous nanoparticles. Nanomembrane clothing has several advantages over Gore-Tex. It is lighter and thinner and allows for greater freedom of movement and a more comfortable fit. Another advantage is that it is made from environmentally friendly materials. Also, the fabric is less prone to clogging with dirt, which can be a problem with porous clothing. So each technology has its advantages and disadvantages. It depends on the needs and preferences of each user, where they move and under what conditions.

So what material to choose?

VAPOUR PERMEABILITY/WATERPROOF/BREATHABILITY. Igelite is great! Waterproof. It doesn't blow. But vapor permeability? Zero, it's not. So back to membranes.
It's always about compromise, quid pro quo. It's raining cats and dogs. Well, probably the "gorac", Gore-tex. Or just another, microporous competition. Rainforest, sometimes Iceland or Patagonia. Monsoon season. I want to party like hell, but won't I get wet? Then a non-porous membrane. In a 3 day downpour I'm going to be partying anyway, the moisture has nowhere to go and the wet feeling is so strong that I'm de facto soaked...
When to choose nano membrane fabrics? A solid water column is usually sufficient. Vapor permeability is much better. For hiking, yes. Climbing and expeditions? Yes. Running down a wild river, moving in the rainforest? Not really. Ski mountaineering, 100% yes.

Want to know more? There's a whole lot of buts in everything...

Hydrostatic resistance, water column. The water column is measured under ideal conditions, on a stretched piece of fabric. Field practice is quite different. It depends on the outer water-repellent treatment, the humidity, the intensity of the rain, the size of the garment. Is it too tight for me? Also on the pressure of the pack, etc. Only plastic is really waterproof. Membrane clothing isn't literally waterproof, it's only waterproof to a certain extent.
What would I prefer? Vapor permeability and hydrostatic resistance, that's kind of the outdoor Sparta and Slavia. They don't work together. An increase in the value of one is accompanied by a decrease in the value of the other. Then there's a whole range of methods of measuring the parameters. Different countries have different methodologies. Sometimes it's about intent, marketing. Measurements in the lab vs. measurements in the field. Comparing apples and pears. Min. 60% of the information presented on the market is nonsense, pure marketing. Some things can't even be reliably measured (100,000 water column). Our contractors' measurement methods are among the toughest. Which can visually lower the numbers. It's then up to the customer to make up their own mind. Even to an informed "outdoorsman" the numbers don't tell much. A layman can't tell the difference between MVTR 30 or 38 thousand... But he can tell how good he feels in the jacket.
So what do the numbers mean to the average user? Are they true or false? It's not just about the numbers printed on the label of the jacket. There are a number of other factors at play that we have to take into account. The problem is the dew point, when the vapour, the gas, becomes a liquid. The water vapour molecule is small, the fabric lets it out, it's not a barrier. The water molecule in liquid form is much larger in volume and will not pass through the pores. If we sweat to the point where the lining is wet, we're out of luck. There's no functionality. If it's pouring, like a watering can, where does the moisture produced by the body go? Outside, the humidity is at the same level and there is no pressure difference, so it doesn't allow the jacket to show its pros. It depends not only on the humidity and temperature of the surrounding air, but also on ourselves. We all have different body thermoregulation and training. It also depends on the base layers, which can make it much harder for the membrane to work if we dress incorrectly.

What else will affect clothing choices?

Membrane clothing offers a number of ways to influence thermoregulation. Drawstring sleeves and legs, pockets, main 2 way zipper or vents. Why have ventilation zips if the jacket has great features? Well, as said, everything has its limits. In an excellent membrane jacket you don't actually use the zippers, but they are useful as a spare. In an inferior membrane, we won't do well without them. The seam taping on membrane clothing also contributes to wearing comfort. What is the reality? I don't know that the effect of sticking or not sticking has been accurately measured. Probably not even possible, there are too many environmental variables. Still, unglued jacket, for the city yes, for the mountains rather not. Nowadays it's fashionable to join parts by welding. But don't expect the same durability as a quality sewn stitch taped together. And expect irreparability. What about so-called sustainability? Which, of course, will increase the price of clothing. And at the point of application, it will limit the membrane's vapour permeability. But it's required as part of the membrane manufacturer's contractual terms, to the benefit of the customer.
Consider that the values quoted, for example, for a jacket displayed in a shop, are for the membrane fabric in the yardage, not for the membrane itself or the complete product. The parameters will affect the design of the cut, pockets, ventilation zips... What cannot be measured is up to each of us to decide which product appeals to us.

Durability of membrane fabrics.

Certainly, the lifespan of membrane clothing is not unlimited. Lamination is actually bonding 2 -3 different materials together, essentially vacuum bonding. And this is where the wear and tear of bending, folding starts to take effect. And washing. Pressures on the fabric won't help either. In other words, if we pull down our boot legs or backpack sleeve straps, we can confidently expect to have a plain chamois from a "no-name" Asian-made membrane within 2-3 years. We used to repair jackets in Faramug, 10 - 12 years old, in solid condition. It's all about how you store the jacket, where and how often you use it. Of course, a stored, unworn membrane jacket after 8 years is not a new jacket. It is just as "worn" as if you had worn it.

Treatment.

And how about the treatment of membrane clothing? There is a lot of information that membrane clothing can be washed indefinitely. Washing too often will accelerate the peeling off of the individual layers that are laminated together. On the other hand, let's not go out in dirty clothes... It is best to wash gently by hand or in the washing machine with the gentle programme on and the water temperature low. We won't spoil anything if we fasten the zippers, even the dry ones. And use special, mostly liquid detergents - they are not aggressive to the membrane. That is, detergent-free and without fabric softener, which will significantly reduce the water repellency. Then rinse the garment thoroughly, washing out any residual chemicals, but don't wring it out. Then, ideally, reiron. But always over a cloth, like a sheet. Or run gently through the dryer on the programme. Activate the water resistance. And don't be afraid to use sprays to increase water repellency.