Breathable Waterproof Fabrics for Outdoor use and why i use Hydrophilic membranes in preference to Goretex

Let me start by giving everyone the opportunity to dump their eVent, Goretex, Aclimatise or any

other type of breathable shell for a piece of gear which is everything you ever wanted in a shell.

Its Light, compact,easily storable, cheap, 100% UV Proof, keeping you cool as well as dry. Its also

100% waterproof - even though the fabric is just uncoated Nylon or Polyester.

Have you guessed what it is yet

I give you the Humble Umbrella

Why am i showing you this, well i believe this is the level of performance users expect from

performance fabrics . The reality is once you you put on any kind of clothing you are going to

reduce the level of breathability, the greater the barrier/ level of protection the lower the

breathability becomes.

The degree of Choice is somewhere  between 

Lets look at the main types of membrane on the market : eVent , Goretex and PU Hydrophilic

Goretex to their credit created the Outdoor clothing market when Bob Gore in 1969 discovered

PTFE could be stretched to form a strong porous material that lead to the development of Goretex

which was marketed in 1976 by Early Winters as the first breathable fabric.

The first generation of the Goretex membrane breathed by nature of the pore size of thePTFE being smaller than a water molecule there by letting moisture vapour through inVapour Form but in turn not letting water ingress from the outside. This product spawned an industry ( which I'm personally grateful for today) . This early product wasn't without issues, dirt and soap products would lodge within the pores eventually reducing the level of breathability.. This led to generation 2 and finally the current Goretex product which has a coating / finish on both sides of themembrane to stop dirt and soap reducing the breathability.

With the birth of a new industry new technologies developed , breathable microporous andhydrophilic coatings, variations of the PTFE membrane with the emergence of eVent and the development of Hydrophilic membranes . ( which are my membrane of choice for use in the Outdoor or services industry)

Goretex Membrane                                                  eVent Membrane

                                                        An example of a Hydrophilic membrane.

Why do i use hydrophilic membranes

Hydrophillic membranes are solid, with no holes in them ( or there shouldn't be) …So they are totally windproof… they breath by allowing moisture in liquid or vapour form to travel uni directionally through the membrane by molecular diffusion moving from the highest temperature to the lowest temperature . Now in terms of breathing you would say a membrane with no holes in it cant possibly breath..and to an extent you would be correct ..but they would transfer moisture creating a microclimate which would keep you dry ( and in my opinion if you are dry on the inside

the garment is breathing)

Breathability testing of fabrics 

The current breathability test that is quoted by the industry tests fabrics in dry conditions with the temperature on both sides of the fabric being 30C with 65% humidity.

When do you ever get conditions like this were you would be wanting to wear a waterproof garment ( a desert). A better test would be to test the fabric at 30C on one side to replicate your bodies temperature and around 8C ( ambient temperature over the year in UK) or lower.

Doctorate studies carried out on breathable waterproof fabrics have shown that as the exterior temperature drops there is a marked increase in condensation within garments …Remember from above microporous products will not let water through in liquid form ..so therefore there is no where for sweat to go as it condenses… Alternatively with Hydrophilic membranes as the temperature drops and the temperature gradient increases so does their moisture transportation ..Please note all this testing is carried out in dry conditions and even under the standard laboratory test good quality hydrophilic membranes perform to the same level as the market leaders

So why would the test houses not replicate real life conditions in their testing and make this the standard : Simple reason companies which market Microporous products and  have big marketing budgets would be totally against it … because they wouldn't work well.

This leads me onto another point :

ALL WATERPROOF PERFORMANCE OUTDOOR JACKET NO MATTER THE BRAND YOU

ARE WEARING WILL CEASE TO BE BREATHABLE AFTER THE DWR ( durable water

repellant) HAS BEEN COMPROMISED

This usually happens after around 30mins to 1hour of continuous rainfall, after this time condensation will slowly build up within garments and you will eventually feel wet… Hydrophilic membranes have a slight edge here as they can also act as a reservoir soaking up excess moisture until saturation is reached but eventually like the microporous products condensation will build up.

So in terms of our brand Aclimatise, we use hydrophilic membranes because they can match the market leaders in independently tested standard  breathability tests and exceed the market leaders performance in real world situations.

In case you think I'm against Goretex I'm not, every product has their place, they created the industry and in my opinion their membrane works best in Fire suits or high temperature environments.

Microscopic photographs courtesy of Shirley Technologies.