Mountain Equipment and hydrophobic down?

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 jackth 14 May 2019

I've been thinking about upgrading my sleeping bag for a while and had pretty much decided on getting the ME Helium 600, which just about covers most of the situations I would use it for, and is in my budget, but then I realised that they don't use hydrophobic down, which Rab and Mountain Hardwear do use... 

Anyone got any particular ideas on why this would be? I mean, apart from this, their bags look excellent, but this just makes me want to consider their competitors more, even if it's just for slightly increased peace of mind. 

Looking forward to hear what you have to say


 Shortshorts 14 May 2019
In reply to jackth:

It's not just ME.   A lot of the more specialised/premium down companies don't use hydrophobic down.  Feathered Friends, Western Mountaineering, nunatak(?), PHDesigns etc.   

There are minor points against it, like how not all hydrophobic coatings are equal, the weight increase and not packing up as small as untreated down (+5%~ iirc). Then there are the concerns over the durability of treated down, and the overall reduction in total loft (so a drop in the fill power).  Which is probably the bigger reason why these companies don't use it. 

 TobyA 14 May 2019
In reply to jackth:

Mtn Equipment's doctor down is (or at least used to be) a regular around here so hopefully Matt might see this and give you a full answer.

Are all their sleeping bags non hydrophobic?  

I wonder if the treatments actually adds a tiny bit to the weight? Or whether they think it doesn't really make that much difference?  I don't think there is any disadvantages to using hydrophobic down but having reviewed a number of bags and jackets now with the treatment I'm not convinced it makes a huge difference over non treated down. 

 richprideaux 14 May 2019
In reply to TobyA:

I too have doubts about how useful hydrophobic down actually is, or at least if it is worth the extra cash or limiting the range of options.

There is a review of the ME Firefly coming up on here soon, and that's 'normal' down. Partly I think to keep the weight and bulk to a minimum.

Fabric choice, design/architecture and placement of insulation probably matters more.

 misterb 15 May 2019
In reply to jackth:

hydrophobic down is or should be tested for ffil power after it has been treated and therefore there should be no weight or volume penalty

 innes 15 May 2019
In reply to jackth:

PHD offer their opinion of proofed down, based on testing, here:  

 Mr Fuller 15 May 2019
In reply to jackth:

Just seen the thread, and like Batman to the Bat-Signal, here I am. We don’t use hydrophobic down in any of our sleeping bags for a few reasons, but the major ones are:

It isn’t a magic bullet: Hydrophobic down increases how long you can use a product for in damp conditions, but it doesn’t make down the perfect thing for, say, open bivvies in the rain (shudder). In most conditions you’re not likely to notice much difference between hydrophobic and non-treated down bags, and we’ve plenty of evidence of non-hydrophobic down bags being used very successfully on prolonged and serious trips. For example, when Tom Livingstone, Aleš Česen and Luka Stražar climbed Latok I over 7 days last year they used a Fireflash bag – ie. not hydrophobic down – and a two-person bag we made in the office, again filled with non-hydrophobic down. Similarly, Ben Saunders' and Tarka l'Herpiniere’s frankly outrageous 105 day Antarctica crossing, packing away frozen sleeping bags every day, was done with non-hydrophobic-down bags.

If you want to keep something dry, you make the outside water repellent: A fair few of our bags have water repellent shell fabrics, and sometimes these line the hood and footbox too, in case of spindrift/snow, or moisture coming off damp socks or inner boots kept inside your bag. A water repellent shell is a far better way of keeping something dry than coating what’s inside! If you’re sleeping somewhere really wet, even if the hydrophobic down inside your sleeping bag stays dry, all the fabrics, stripping, and construction of the bag will get soaked, which is just grim: if you’re driving a convertible car you don’t put a waterproof jacket on when it starts to rain; you put the roof up.

Down sleeping bags last a long time and hydrophobic coatings don’t: We have plenty of customers get in touch about bags that are 20 or 30, even 40 years old. We all know that DWRs don’t last very long – think of your waterproof jacket – and even though hydrophobic down lasts longer because it’s inside a sleeping bag, it won’t last anywhere near the lifetime of the bag. It’s hard to estimate on lifespan because there’s lots of factors, but we’d guess maybe a year or so with regular use.

Down is hydrophobic to start with: Down is very water repellent in its ‘natural state’: both geese and ducks have extremely hydrophobic feathers. Go down to your local park and look at the feathers beading on a duck when they clean themselves: it puts man-made technology to shame. The problem is, down smells and can rot easily if it isn’t cleaned of a lot of these natural oils, so we thoroughly clean it, but this also reduces its hydrophobicity. It’s a pretty inelegant solution to then dunk a load of synthetic chemistry on these cleaned feathers to make them more hydrophobic again, especially when, as an industry we are being pressured to reduce the number of coatings, treatments, etc. being used. We’ve tested a huge number of different options and in general, the more environmentally-friendly the technology at application, the less long it lasts; the more environmentally-harmful treatments last longer. By the way, contrary to popular belief, down isn’t really vulnerable to water: it floats on water for starters, despite being denser than it.

There are other ways to stop down getting wet inside a sleeping bag: Alluded to in one of the posts above, and I’m not going to go into much detail because it’s mostly stuff we try not to tell everyone, but you can do a lot with where and how you put down in a bag to make it more water resistant. This is where the most interesting stuff happens.

We use some hydrophobic down in our lightweight down garments which are fairly likely to be used for short periods in damp conditions (think of jogging back to the car as the rain starts at Stanage), and it’s perfect for that use. Similarly, those sorts of garments are fairly likely to be used above freezing in dank weather, and having a coating that makes them dry out faster is beneficial.

As mentioned above, hydrophobic down doesn’t affect weight or volume of the down (the treatments are nano-scale) but we don’t know everything yet about its long term effect on loft, etc.. As a bit of trivia, the first experimentation with man-made hydrophobic down started because the American military had an unreliable supply of down during World War II and were trying to make their plentiful chicken feathers work like down by covering them in chromium salts. It didn’t work…

Dr Matt Fuller, Mountain Equipment

pasbury 15 May 2019
In reply to Mr Fuller:

Well you've convinced me!

 Tom F Harding 15 May 2019
In reply to Mr Fuller:

Thanks for the really informative explanation. Do you have any toughs on Patagonia's Encapsil 1,000-fill-power hydrophobic down? It disappeared as soon as it arrived but seemed like a really interesting technological advancement.

 Mr Fuller 15 May 2019
In reply to Tom F Harding:

In a past life I posted my view on Patagonia's Encapsil jacket here: (note, six year old post where I didn't work for my current employer)

I haven't had any first-hand experience with plasma treated down, but there were reports online of it clumping. I agree that it was a really interesting development but unfortunately that doesn't always result in great real life use; the fact it's disappeared from the market suggests that, or that costs were prohibitive. My concern with plasma treatments is often their lifespan: they're molecular surface treatments and so can usually be rubbed off easily. P2i do some amazing work in this area and are plasma-treating, for example, the insides of phones so they don't get wet. That's a perfect application for plasma.

Post edited at 13:44
 Southvillain 15 May 2019
In reply to Mr Fuller:

By the way, contrary to popular belief, down isn’t really vulnerable to water:

Otherwise ducks, geese and swans wouldn't use it.

 LastBoyScout 15 May 2019
In reply to jackth:

Not that I can really follow Matt's post, but hydrophobic down in a jacket makes sense, as it's more likely to get caught in a rain shower.

If you're careful about using/carrying your sleeping bag, it shouldn't really get wet anyway.

That said, I've had a couple of occasions where I've got a damp bag after it's got a bit of condensation on it where it's touched the inside of a tent. I've known people that have used a bivvy bag inside a tent for this reason. ME (and others) went through a phase of making bags with DriLite (and other) outers, but that seems to have gone out of fashion, as they were heavier.

There are products like Nikwax down proof that you could try if you were that keen on the idea and wanted the extra reassurance.

OP jackth 15 May 2019
In reply to Mr Fuller:

Thanks all for your input - illuminating! It's certainly made me reconsider how what to look for in down gear. I wonder, Matt, whether it's worth including information like this somewhere on ME's website, just to offset people wondering why they don't use it when their competitors do?

One of my main thoughts was: why not opt for it when there are few downsides, even if the benefits aren't enormous? But you've certainly gone some way into arguing that we should be thinking "why" rather than "why not". 

 Damo 16 May 2019
In reply to Mr Fuller:

> In a past life I posted my view on Patagonia's Encapsil jacket here: (note, six year old post where I didn't work for my current employer)

Thanks for the good info above, Matt. I was sceptical of hyrdro down from the beginning, as my comments in that old thread show.

It struck me as marketing more than reality, a play to gain market advantage in an otherwise race to the bottom. Patagonia in particular has always had a thing about wet down. For many years they had no down garments at all, only synthetic, then finally relented - presumably also for market reasons.

Fwiw, as I think I've written here before, I used to spend 50-70 days in a row in my bag (mostly a FF Snowy Owl -40C but also a Paddy Pallin Twynam)  in Antarctica and never once have I had a problem of the down being affected by moisture or ice inside etc.

 Root1 16 May 2019
In reply to jackth:

PHD who know a thing or two, do not use hydrophobic down as it is unproven. Hydrophobic down is basically just treated with a DWR coating which is anything but durable! They prefer water resistant or even waterproof covers.

In reply to Mr Fuller:


Maybe you can explain this?

I have a ME Marathon 300 bag, 650FP, waterproof Lightline jacket and Rab Ladhak 1000 bag, 550FP. These are 25 year old vintage, still in regular use.

Have geese/ducks evolved since then, to produce fill powers in excess off 800 or are there other factors involved? Back in their day, these were as good as it gets.



 Frank R. 16 May 2019
In reply to Mr Fuller:

So what's your (and others') take on fighting condensation in the cold around the face area? I had high hopes for HP down there originaly, but seeing that quite a lot of manufacturers like SJ, ME and others are not using it, presumably for similar reasons? Sorry if it's a small digress from the "just ME" original question. Tried shawls (more like "ice-traps" ) and WP-membrane bags with varying success.

Not asking you to divulge any trade secrets, of course

 Mr Fuller 17 May 2019
In reply to Stuart the postie:

There's a few factors at play here. One of them is that the method of conditioning down before its fill power is tested has changed. It used to be that down was just sat in a box for a while and then fill power tested. Then they started doing water rinsing of the down. The fairly universal method now is to steam condition the down. Steam conditioning makes for more reliable fill power results and it is also a relatively quick way of conditioning down: a major consideration in a busy testing lab. However, it also produces higher results than the other conditioning methods. The IDFL have published quite a bit of info on this if you ever want a look. The other factor, which provides an actual benefit to the consumer, is that down sorting methods have improved a bit. The sorting houses, which work a bit like fractional distillation in that the best down flies the further down the sorter while the less good stuff gets stuck near the start, are bigger and more powerful than they were, allowing better quality down to be separated.

 Mr Fuller 17 May 2019
In reply to Frank R.:

Biggest thing is not to breathe into the bag and try to keep some sort of passage for water vapour to escape, but we've found Gore-Tex Infinium about the best stuff for stopping the bit round your mouth getting damp. It's very breathable and very water resistant and stands up pretty well to icing up. Other than that, fabrics with water resistant coatings are very effective too because they keep most moisture out but don't hugely impede breathability. Of course we also do some clever down stuff

 TobyA 17 May 2019
In reply to Mr Fuller:

> Biggest thing is not to breathe into the bag and try to keep some sort of passage for water vapour to escape, but we've found Gore-Tex Infinium about the best stuff for stopping the bit round your mouth getting damp.

In a bivvy bag that can be quite tricky because even if you aren't breathing into your sleeping bag the moisture can get trapped between the bivvy bag and sleeping bag - lots of ice in cold temperatures or lots of moisture when above freezing.

I'm still quite pleased I had the presence of mind to take the last photo in this review that shows just how much "breath frost" you can produce!

 Dell 19 May 2019
In reply to jackth:

So this single thread has managed to debunk 6 odd years of marketing. 

What will be the next hot UKC topic? 

Smoking. Is it good for you really?


This guy is really taking one for the team.

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