Jon
I have this post copied from another site. It saves me typing, essentially, the same thing out -
In its essence a waterproof needs to stop water getting in and let the water you’re generating by walking out (as best as possible).
Most waterproofs that work best use a laminate layer, that’s sandwiched between a “face” layer, and an inner liner layer. This laminate “breathes” - as in it has tiny holes that block water droplets, but let water vapor (ie the heat sweat you’re generating) out.
First “gotcha” to keep in mind; marketing teams will have you believe that their laminates (gore Tex, eVent, Ecoshell, torrentshell to name a few) will let you sweat out, and prevent water in. They will stop water getting in, but the second your sweat turns from vapor to liquid sweat, you’ll “wet out” from the inside and that prevents the laminate breathing any more. So you get wet anyway. “Breathability” and the measurement of it is in short, a myth. It works if you’re standing still or doing a low activity descent, otherwise forget it, including the numbers they throw out.
Bear that in mind that if you buy a laminate, the only way to get rid of that sweat whilst walking up is to open the vents, which means you’ll let water in the side. But ensuring you DO have vents is very important because no matter what the marketing teams tell you, it’s the ONLY way to get large amounts of body heat out of a shell. Laminate isn’t magic.
Most shells use a laminate, they all have different names, but frankly they’re all basically the same. They use a system of measuring the “hydrostatic head” of the fabric shell to work out how waterproof something is. This is measured by placing a 1 inch square of the material under a long glass tube and seeing how much it fills up to work out the pressure. In the rest of the world, a fabric must resist up to 10,000ml of this to be able to be called “waterproof”, in the UK it’s 15,000ml. Either way it’ll be functionally waterproof enough. GoteTex is 20k, Fjallraven’s Eco Shell is 30k. It’s meaningless really, after a certain point.
Some modern versions like The North Face use woven waterproofing, where the fabric is woven into the whole thing. I bought into it when it was released, and it fucking sucked, I got soaked. Don’t bother with these. Focus on the laminates. (I use a Rab proflex for travel but I wouldn’t use it as my only jacket)
You’ll see 3 layer / 2 layer. That’s the number of layers over the laminate. It makes the jacket heavier or lighter, trading off vs robustness. To be honest, either will be fine for your use don’t stress about it.
So look at laminate waterproof, 2 or 3 layer with a hydrostatic head of at least 20k with pit vents, and you’ll be fine.
Other thoughts.
There is a manufacturer that went totally left field, it’s called Paramo. It didn’t use a weave or a laminate. They went off and copied animal fur, then sandwiched it into two layers. It, unlike the laminates, will move water liquid off your skin as well as vapour. It’s not a waterproof shell though, so relies on constantly pulling water away from you than preventing it getting in. They’re also significantly more comfortable to wear than other shells. Note that UK mountain rescue (not all, apparently) use them… and they’re produced in one factory in South America specifically set up to make them, and they only hire women to provide upwards mobility to the local area. The jackets are also designed to be repaired indefinitely, for the whole life of the jacket (unlike a laminate shell which is usually fucked once it’s ripped)
I know I’m sounding evangelist here, but I don’t actually have my own; that said, on a recent 12km a in the temperate rainforests of the Pacific Northwest in constant downpour, I was wearing a v expensive fjallraven laminate shell jacket and trousers, my gf had a full paramo set, and I got wet an she didn’t. So although it’s not mainstream, it really does work, in total downpours.
Whichever jacket you buy please please remember you need to keep the shell waterproofed. Use “Nikwax” in the washing machine. Do this because it will make water bead off the shell layer, which prevents the jacket wetting out, which allows it to breathe longer. Keeping it waterproofed is essential.
