View Full Version : Any Gore-Tex experts on -20dF Down Bag?
I have a Marmot -20dF GoreTex shell down bag I bought 25 years ago. It kept me warm at -25dF in W. Virginia one weekend:).
It is 800 cu/in fill, and is superbly made, back when Marmot was still a niche manufacturer for serious Alpinists.
The bag is in great shape, because frankly I haven't used it that much, maybe 2 weeks total in that time. My "mountaineering" days were numbered shortly afterwards.
What I would like some expert opinion on is whether the GoreTex shell has been found to be inferior, replaced by something that breathes better. I could see how the lack of breathability would create a reduction in vapor transmission at the interface between the warm interior air, and the much, much colder exterior air.
Should I look into sending it back to Marmot as "defective equipment?" Though honestly, I'm not seeing myself doing that much winter camping anymore. (Well, nothing more than a long weekend in the Smokies or Blacks, and not sub-zero, at any rate.)
There's surely newer waterproof/breathable membranes that perform better, but if you're actually using the bag at anything near it's temperature rating, you should be using a VBL anyway.
Should I look into sending it back to Marmot as "defective equipment?" Though honestly, I'm not seeing myself doing that much winter camping anymore. (Well, nothing more than a long weekend in the Smokies or Blacks, and not sub-zero, at any rate.)I wouldn't even for a moment think that sending it back to Marmot as so-called defective equipment would even be a possibility. You've had the bag for 25 years, what would all of a sudden make it defective? I'm not going to get on a soapbox here, but when you buy a piece of gear, it becomes your property and responsibilty to use and maintain properly. If, after 25 years, it no longer meets your needs, doesn't work right anymore, etc., then that's not the problem or the responsibility of the manufacturer. IMHO, trying to return a piece of gear that you purchased 25 years ago is nothing short of bad decision making and irresponsible. If you want to get rid of it, sell the thing in your local classifieds, Craigslist, eBay, etc.
Hooch, dude, ease up.
I am not at all interested in scamming Marmot. The sleeping bag is a great piece of gear. I bought it and own it, and I have not at all treated it badly.
I used to manage an outdoor outfitter, back when I bought the bag, and I saw plenty of people trying to scam the lifetime warranties to turn my stomach. I would never do that.
I've made plenty of decisions which I "owned" and didn't try to pass of to others.
Likewise, the ONLY reason that I would return it to Marmot, is if they themselves feel that GoreTex was a good idea at the time, but fundamentally "defective." In other words, they thought that it would breathe well-enough, but it doesn't.
That is why I was asking for experts about the technology.
Again, any experts that might have an educated opinion about the development of technology that can provide some insight (i.e. facts & knowledge)?
That's an interesting question. I have a Canadian Forces gortex bivy that seems to work great for both waterproofness and breathability, but it is rather heavy at 2 pounds. It could be that Gortex was deemed too heavy for most applications, and didn't work so well when they tried to make it lighter. If it wasn't for the bivy I would say all gortex type technology is hype, but the bivy does work, though its heavy. I am still not sure if its better to get sleeping bag with the lightest shell possible, and then use it with a bivy or tarp or tent, or whether it might be better to try and use a more protective shell on the outside.
Not sure if that answers your question.
Thanks, JAK. I think GoreTex works well for waterproofness, and I think it breathes better than pure impermeable barrier. But it sure doesn;t breathe as well as nylon taffeta.
GoreTex does work, but it has been hyped as a "wonder fabric," and it does have its limitations that most users do not understand. The problem with GoreTex raingear (not sleeping bags):
(a) when it is raining, the vapor density inside the shell is equal to or greater than that outside the shell in the humid, rainy air, so there is not adequate vapor differential for it to transpire out---this results in heat and humid buildup inside the shell, and eventual saturated clothes if exertion is robust;
(b) when the outer shell fabric gets saturated and "wets out" with rain (after the DWR treatment wears off), there is now a water barrier that vapor will not be able to pass through, even if the vapor pressure were lower outside;
(c) GoreTex, while breathable, is still a barrier, and it doesn't breathe perfectly...neither does a cotton T-shirt, and it is massively more "breathable" than GoreTex. So even using GoreTex as a windshell will result in a very hot and humid environment inside the shell with exertion.
Were I to do it again, I would go with a bivy, if for nothing more than the flexibility.
I have thought about making a lightweight PrimaLoft bivy shell to use with my regular REI 20dF down bag, both as a way to "stretch" the temp rating to 10dF or maybe even 5 dF, but also as a way to have that 1/2" to 1" of barrier as synthetic.
The idea would be that the shell would be a condensation matrix between the interface of the warm moist air transpiring of the down bag and the cold dry air outside.
I think I'll just call Marmot and see what they think about the situation.
They may have some people who lived through the GoreTex transition to what they are using now...their proprietary MemBrain.
I'll let you know what I find out.
i would think no. goretex was invented to replace the polyeurathane rain gear people were using at the time. now the poly rain gear is absolutely not breathable, and goretex was a step up from that some 20 or 30 years ago. they still sell jackets and pants made of the totally waterproof but totally not breathable poly.
using your line of thinking you could in essense return any product that has ever had an improvement made on it, so i don't think your goretex bid has legs to stand on
Hooch, dude, ease up.
I am not at all interested in scamming Marmot. The sleeping bag is a great piece of gear. I bought it and own it, and I have not at all treated it badly.
I used to manage an outdoor outfitter, back when I bought the bag, and I saw plenty of people trying to scam the lifetime warranties to turn my stomach. I would never do that.
I've made plenty of decisions which I "owned" and didn't try to pass of to others.
Likewise, the ONLY reason that I would return it to Marmot, is if they themselves feel that GoreTex was a good idea at the time, but fundamentally "defective." In other words, they thought that it would breathe well-enough, but it doesn't.
That is why I was asking for experts about the technology.
Again, any experts that might have an educated opinion about the development of technology that can provide some insight (i.e. facts & knowledge)?
If it was a good idea at the time (25 years ago) then you bought a good idea then. To try to get your money back now under the circumstances you describe is beyond ridiculous. You really need to ask some experts on ethics.
You guys are reading WAY to much into this; questioning my ethics and intentions is really kind of laughable!
Maybe I opened myself up to it, but hey, it's hard sometimes to fully understand what someone else is trying to express in a forum. So I'll forgive you and move on.
I called Marmot, and they said they have migrated to Membrain because it is cheaper than Gore (don't have to pay the cost & royalties) and that it IS much more breathable.
But there are no fundamental technical problems with what they call "classic GoreTex."
So for any of you folks who have "classic GoreTex" shelled bags, unless you've not taken care of it, no worries about it's use in those bags. It will still work like they intended.
I don't call myself an expert, but I think U R starting to get into several ideas of breathabilty. Breathabilty is as much a marketing term as it is a real life scientific measurement. There R various versions and types of Gore-tex. Some types and versions R more breathable, when quantitatively scientifically measured, than others(hope all those big words don't lose U). Just trying to make a clear distinction between marketing hype and real world scientific measurements. No, I can't say that I can ever recall Gore-tex technology to be considered defective. So, I can't see grounds for returning this bag to Marmot as being defective solely because of Gore-tex technology or because newer Gore-tex versions have advanced. Gore-tex is stilll widely used in its many versions and types for a wide range of outdoor gear. However, there R other fully waterproof membranes that rival or beat the breathabilty of Gore-tex. EVent is one of them. If U want to WP a sleeping bag, or at least make it highly water resistant, there R several other ways to go about it. I'm not going to get into all those ways here, but U could get a sleeping bag with a WP/WR/DWR shell, like U did with the Gore-tex shelled sleeping bag. If U decide to go this route, as U have realized, U will compromise breathabilty and wt. of the bag. Like U already alluded to, another option is to add an overbag/bivy; IMO, and what I do, is to go this route because it gives me more flexibility in designing my sleeping bag for the conditions I'm most likely to encounter. One last mention of Gore-tex is that U R seeing more and more gear manufacturers ditching patented Gore-tex(almost certainly because it demands a steep price) and going with their own proprietary or less expensive alternatives. According to my research, Gore-tex and its many forms have been much more independently studied, measured for breathabilty, and compared to other WP technologies than many of the other proprietary WP technologies currently being employed by some gear manufacturers. An exception to this is EPIC and eVent. From what I can tell, eVent is the supreme fully WP most breathable fabric/technology available.
Meant to say some notable exceptions to this are EPIC, eVent, and Pertex(WR) technolgies.