Waterproof Jackets – Busting through the Jargon

waterproof jackets

You thought that buying a new waterproof would be easy!

But then you heard Membranes, Hydrostatic-Pressure, Taped Seams, DWR, 2.5 layer, Breathability, Wind Resistant, Wet-Out, Pit Zips, Articulated Arms, Helmet Ready Hood …the list goes on and on.


It’s a bit like buying a car.

In general, if you just want to nip to the shops there is the perfect city car but if you need to add a bit of adventure to your driving you can upgrade to the all-singing all-dancing off-roader.


This blog won’t cover all the terms, you can head to the glossary for that. I just wanted to share some of the key facts about waterproof ownership.


robert gore goretex

First is the elephant in the room – Gore-tex.

A big thank you to Robert Gore who in 1969 invented the waterproof, breathable fabric membrane.

Without him we may still be wearing smelly oiled jumpers, heavy waxed jackets or simply getting wet.

Gore-tex is like Hoover in that its name became synonymous with the technology it was selling.

Is Hoover still a good brand? – of course it is but I have a Shark and it’s also very good.

There are now a number of excellent companies that make this type of membrane so don’t get fixated on one.


drymaxx waterproof membrane

The significance of the invention is to simply stop water coming in through the fabric and still amazingly let moisture out.

Magic? Well not quite - just chemistry.

Microscopic holes in the membrane means the rain droplets were too large to go through but water vapour, which is smaller, can get out. It also makes the fabric windproof.


tweed climber chris bonnington


Another added benefit to this membrane is it can be bonded to different fabrics.

This is where the hikers took notice.

Walking in tweed and corduroy could be dispensed with in favour of lightweight polyester bonded with this new concept membrane.

Walkers could stay dry in lightweight clothing and more importantly the moisture inside the jacket, building up from activity, wasn’t trapped inside.

Now, first thing to ask yourself is what activity do you need the jacket for. You may be drawn to the all-singing all-dancing off-roader in the showroom, but do you actually need it?

hydrostatic testing fabric

This is really where the hydrostatic-pressure test comes into play. Water pressure is exerted on the fabric for a 24-hour period and it is measured in millimetres.

What this means to the walker is the length of time they can spend outside in the rain.

You can get jackets that will keep you dry for 60 minutes in a light shower while nipping from the car to the shops. Others will keep you dry for 24 hours when walking the Ridgeway in pouring rain and driving wind.

Rule of thumb here is the higher the number the longer you can expect the rain to stay out of your garment. 5000mm is acceptable, 10000mm is good, 20000mm is excellent.



But here is the rub - not all jackets will use the same fabric. Some are thicker and heavier so they can take a bit more of a beating when brushing up against rocks, while others are thin and lightweight, so the walker can enjoy their time in the rain and not feel weighed down by the coat.

You have probably guessed that the fabric thickness must have an impact on the breathability of the garment and you can also guess that this is also measured.

This measurement is based on the level of vapour in litres that can pass through the fabric over a 24 hour period. Again, general rule is a lightweight fabric will have a higher level of breathability but is likely to be more susceptible to damage.

If the activity means exertion and sweating go for the more breathable and lightweight of the jackets otherwise you will end up as wet on the inside as the jacket is on the outside.


under arm vent

I think that the misunderstanding for many of us is that you somehow won’t sweat when you are walking up a steep incline when you are wearing your new super expensive waterproof/breathable jacket. The fabrics are good but they don’t work miracles.

Help the jacket to release the vapour build-up by opening vents under the arms, if it has them.

Important point here though is that the moisture coming out of your skin does need to flow through the other garments you are wearing. A nice cotton t-shirt will simply soak up the moisture and not release it to the jacket.

Try to choose clothing such as bamboo, merino or some modern polyamides that allow the moisture to pass through them. It is definitely the best way to go.


grangers performance wash

Finally, this brings us onto a product that is applied to the outside of the fabric during the manufacturing process: Durable Water Repellent Coating (DWR)...Clever stuff.

When the jacket is new it will shed the rain like water off a ducks back. This means the membrane can release all that vapour as there is nothing in its way.

However, this coating is not 100% durable and will start to wear off overtime, especially in areas that are rubbed, such as shoulders with bags and packs or the inside of the elbow.

Also, at the same time the fabric is picking up dirt on the outside. When this happens, the rainwater doesn’t run off anymore and this creates a problem as the vapour now has a barrier of water/dirt/grease in its way and cannot get out.

So, in persistent rain the fabric simply holds onto the water and doesn’t release it. This is known as ‘fabric wetting out’.

You are now effectively wearing a plastic bag and if you have ever worn a bin liner you can get a bit sweaty inside.

grangers repel

Probably the most important thing to learn here is that it is unlikely to be a membrane failure, and it is not necessarily the end of your lovely waterproof.

As luck would have it washes have been invented to clean your jacket so all those tiny holes are kept nice and clear and then you can re-apply that all important coating back onto your jacket keeping you dry and damp free.

Washing your jacket regularly is not an issue and in fact is essential, just use the right products.

Now if you have read this far, thank you and I hope that this gives you a little more insight into waterproof clothing…and remember

"life is not about waiting for the storm to pass it about learning to dance in the rain."

Although a good waterproof jacket makes it more fun!

halti waterproof jackets 

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