I was posting a comment on Alan’s blog when i realised it was far too long and that it was better to put my thoughts as a post and link it.
We, in the Outdoor Hiking world, i believe, have been hoodwinked for years. I tend to side with the comments made by Gordon Green that the perfect material has been developed but it daren’t be released because that would be the end of us buying new “Waterproofs”.
The words relating to the jackets themselves defy what they actually mean. I am as guilty as anybody out there when i say, i want a new waterproof jacket but it has to be breathable. Waterproof and Breathable? Please!
Well to what degree do we want this phenomenon. 100% Waterproof and 100% breathable, that’s what we require.
Or as near as i can get it we later admit.
And there we have the first contentious point, you cannot get a hiking jacket with those statistics so we succumb to as good as we can get, and i am sure that in some cases we might not even realise what we have. This leaves massive areas of manufacturers graphs on hydrostatic head, breathability, tear strength, seam sealing, etc, etc. that you can look at if you really want to, but not here. This is just an experienced and practical posting.
Many people buy a waterproof because that's exactly what it says on the tin or label. They have no idea to what degree that waterproof statement relates to.
What is the material, what is the layering, there are so many different materials to choose, to name a few, Gore-Tex, eVent, Drillite, Aquafoil, Paramo’s Nikwax, but there are many many others to consider. The thing with all of them is that they are not water PROOF only water Resistant to a figure determined by it’s hydrostatic head. The greater the number ie 10,000 mm the better the water resistance to leakage than 1000 mm.
What is hydrostatic head? It is the pressure of water required to penetrate the said fabric measured in mm. Heavy or wind driven rain has a higher pressure to light rain.
Waterproof jackets with a material head of 1000mm or less can only be regarded as shower resistant.
1500mm suitable for summer walking and so forth until you get to the likes of 10,000mm which is a minimum suitable for winter high altitude walking. 20,000 mm and even 40,000 mm being as good as you could get currently. See HERE for some comparative figures.
Then there is breathability. This is the ability to transfer warm moisture vapour through the layers of the jacket.
It’s measured in grams per square meter over a 24 hour period. Or g/m/2/d. Typically you want the water resistance say 10,000 mm to equal breathability 10,000g/m/2/d.
But, the practical issue here with breathability is that the fabric allows internal warm moisture vapour through the microscopic holes in the fabric which are such a diameter as they will not allow rain to get through but will allow the warm smaller molecules to exit.
The problem is we all have different metabolic rates. Some of us can walk at a good pace up hill and hardly break sweat whereas others will be wet through and if it’s raining as well then the jacket gets deemed not waterproof by the owner.
Also, it depends on how many layers you like to wear under the waterproof outer. Too many layers will result in the warm vapour loosing it’s heat before it reaches the jacket and therefore it cools and cannot escape, this then condensates on the inner surface and is then transferred back onto your mid and base layers.
The term bomb proof, i take with scepticism when talking jackets and tents as it depends on so many important scenarios many relating to the individual and again you cannot get 100% waterproof and breathable.
Another important issue is the strength of the outer fabric. If your backpacking or daypacking the jacket outer material must be able to withstand the riggers, the abrasion of carrying the weight you take. Many jackets mix materials in high stress areas when a jacket has been made for backpacking but others don’t, especially the lightweights. Once the outer material starts to show signs of wear in these areas, ie shoulders, back and hipbelt, the chance of it staying waterproof are nil.
Now, hiking gear has seen a transformation of late and gear has moved into the realm of the fell runner. If he can wear trainers, windproofs and lightweight waterproofs on exposed runs in adverse weather so can we.
But the trouble is he doesn’t carry a hikers backpack, he’s constantly on the move/run and therefore he/she stays warm and more often than not the exercise only lasts for short periods of time. So you must take this into consideration when buying lightweight backpacking gear if you want it to last more than one outing or at worse fail on a trip.
Of course you get the multi day challenges like the OMM and similar and also overnight orienteering where this light gear is used but it isn’t anywhere near used or abused as it would get on a long backpacking trip.
Another important issue not to be forgotten is the actual design of the jacket. How well it fits you, how good the hood is, if you don’t climb in it then don’t buy one that says hood compatible. It will fit like a sack and leak like a sieve.
The hood is extremely important and it is surprising how often this gets overlooked.
Check accessibility of the pockets and pull chords against what you will be carrying.
Make sure that the cords don’t wick water back between the layering of the jacket and make sure rucksack harness’s don’t rub the zip material.
Don’t buy one with masses of stitching which then has to be sealed with tape which with time will deteriorate and start to come apart.
Look at the zips! There are more and more water resistant zips on outer gear now. This has lead to the elimination of rain gutters and wind deflectors that used to be present behind the zips. A big mistake in my view as any water ingress in these resistant zips is transferred onto your inner clothing directly.
Unfortunately cleaning your jacket is important to it maintaing whatever standard of waterproofing and breathability it started life with.
There is so much to take into consideration when talking waterproof jackets there isn’t a definite answer that will suit everybody but hopefully my post will at least give others food for thought and realise that being waterproof is not entirely what it seems..
The only thing that is waterproof and breathable is an umbrella.
More very interesting reading on the subject can be found Here.