Sleeping bag liners.

[Mike harpe]

I have an old woodland cammo 3 piece army sleep system. Good down to -35 or something like that. Its bulky but allows you to have the light sleeping bag or heavy one by itself, combine the 2, and also use the bivy cover separately or with either one. Essentially you have like 7 different combinations

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[Titans]

Since we are on the topic of R-values: do any of you know what happens with the estimated R value when you layer 2 sleeping pads? For winter car camping in 15F or lower temps we got a Thermarest Neoair 4-season R=4.9 (sale REI outlet) and we will also use a silver Thermarest foam pad R=2.8 underneath the Neoair in a tent. That combined with the Marmot 0F which translates to a 15F comfort temperature sleeping bag, (heavy bag- but for winter car camping).
1) will that be warm enough in 15F?
2) can you add the 2 R values, or doesn’t it work that way?

 

[OwenM]

Reiterating a lot of what's been said, but I'm a sleep system nut, and it's my favorite gear topic.
Those thin liners are for keeping your bag clean. They don't add appreciable warmth.
Here's what Western Mountaineering says will, supposedly based on testing, add 10F to your sleep system(Everlite-yeah, I'm in that):

Based on my own experience doubling up with an older 50F quilt, I'd say that 10F number is extremely conservative, but the point is that they don't claim their silk or poly liners add any warmth at all.
For the weight, heavier baselayers, higher r value pad, etc. are much more effective.
I use a R3.3 Exped Synmat Hyperlite pad and underrated "30F" Katabatic Palisade quilt a lot. When it starts getting much below freezing, I switch to a R5.9 Downmat UL7. As an exceptionally warm sleeper, that gets me into the teens before I need to wear a down jacket and switch from lightweight baselayer bottoms to grid fleece ones(which I've used into negative single digits). <<<Those are, unlike a thin liner, all things that add significant warmth.

Combined with a Klymit Inertia X Lite pad, the Thermolite Reactor liner does give me a sub-1lb sleep system for Southern summers, when when it's warmer in my tent than in my house

 

[Brendan S]

Since we are on the topic of R-values: do any of you know what happens with the estimated R value when you layer 2 sleeping pads? For winter car camping in 15F or lower temps we got a Thermarest Neoair 4-season R=4.9 (sale REI outlet) and we will also use a silver Thermarest foam pad R=2.8 underneath the Neoair in a tent. That combined with the Marmot 0F which translates to a 15F comfort temperature sleeping bag, (heavy bag- but for winter car camping).
1) will that be warm enough in 15F?
2) can you add the 2 R values, or doesn’t it work that way?

Yes you can just add R values. Id think for most people that should be plenty sufficient at 15 unless you’re a really cold sleeper. I’ve slept plenty of nights in single digits with a 1/2” CCF pad combined with an Xtherm. IIRC at freezing you need about R5 (total, so you’ll get a small amount from your compressed bag and clothes as well) to not lose body heat. Obviously that’s not a direct correlation to comfort and and a lot of people are comfortable to lower temps with that R value.

 

[Bob]

Since we are on the topic of R-values: do any of you know what happens with the estimated R value when you layer 2 sleeping pads? For winter car camping in 15F or lower temps we got a Thermarest Neoair 4-season R=4.9 (sale REI outlet) and we will also use a silver Thermarest foam pad R=2.8 underneath the Neoair in a tent. That combined with the Marmot 0F which translates to a 15F comfort temperature sleeping bag, (heavy bag- but for winter car camping).
1) will that be warm enough in 15F?
2) can you add the 2 R values, or doesn’t it work that way?

Basically don't believe them ... Have to try them to find the one that works for you .... Just like stated the temp values for bags.... Not accurate

 

[Mike harpe]

Basically don't believe them ... Have to try them to find the one that works for you .... Just like stated the temp values for bags.... Not accurate

I agree with finding what works for you. I'm a hot sleeper and had to put a window ac unit in my bedroom in south georgia. I miss colorado. When it was winter I'd have the heater at 65 during the day and like 62 at night. I'd sleep with the window cracked in my room as well. It was probably 50 in my room or worse during the snow times, and my nuts were shriveled, but I was sleeping like a baby. The colder the better. If I get cold I'll out socks on my feet. That's it. Sometimes a t shirt.

I made the mistake when I first joined the army of sleeping in full clothes as night. Woke up the next morning covered in sweat and shivering. Never made that mistake again and slept damn near naked after that.

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[Wanderlust073]

Since we are on the topic of R-values: do any of you know what happens with the estimated R value when you layer 2 sleeping pads? For winter car camping in 15F or lower temps we got a Thermarest Neoair 4-season R=4.9 (sale REI outlet) and we will also use a silver Thermarest foam pad R=2.8 underneath the Neoair in a tent. That combined with the Marmot 0F which translates to a 15F comfort temperature sleeping bag, (heavy bag- but for winter car camping).
1) will that be warm enough in 15F?

I think you’ll be sleeping clothed with coat/hat/gloves. I have a similar setup but -20 bag and at those temps on snow I’m going to bed with everything on.

Bodyfat levels also factor in, so it’s hard to know if someone’s experience would be applicable to your own. Some people are bringing more insulation to the trail than others

 

[Brendan S]

Basically don't believe them ... Have to try them to find the one that works for you .... Just like stated the temp values for bags.... Not accurate

Of course they aren't always "accurate", but if they actually give a standardized (ie EN 13537) rating or a fill amount it's pretty reasonable to compare your own experience with a bag rated under the same system. I've made a lot of bags and quilts (both down and synthetic) and can very accurately predict my comfort level based on the loft/fill I put into a bag regardless of design, and same goes for if a commercial manufacturer gives me a fill weight.

With R value, it does matter how you use the pad. As @Wanderlust073 mentioned, body fat (as well as age, gender, etc) matter, if you are a side sleeper vs back sleeper (more conduction to pad if you are a back sleeper), as well as how much you inflate an inflatable pad. BPL did a massive state of the market study some years back where they measured an R-value range based on inflation (fully inflated vs inflated to a level where you are almost touching the ground), for example the original Neoair had a R-value range of 1.6-6.1 (claimed 2.5). Pads that incorporate CCF suffer less from loss of insulation at lower inflation levels.

In sum, obviously some skepticism of manufacturer claims is warranted and there are a lot of factors at play when it comes to sleeping comfort, but measuring insulation values isn't rocket science and numbers are meaningful if you are comparing apples to apples. You don't have to just blindly try a bunch of expensive gear to find something that works.

 

[Titans]

@Wanderlust073 - Yes, I’m expecting coat, hat, gloves in addition, all evening too. He... funny about the body fat, yes, important! Supposedly women’s sleeping bags have more filling than men’s, as men generate more heat. This conversation could go downhill soon

@Bob - I do think @Brendan S is very sensible and helpful in general. We will for sure test it out on our trip and I will report back. I got the Marmot bags, because they have an EN rating, but we shall see. I know we are much, much better set up than last year. Hopefully the combination of everything will work out, so we can get some new amazing star photos.

@Brendan S - thanks, you are always very helpful, I appreciate it! (Our posts overlapped.)

 

[OwenM]

Not sure how bodyfat(or muscle mass, for that matter) figures in. I often wonder if it does at all.
Women typically have a higher bodyfat percentage, yet also typically sleep colder.
My body composition has varied wildly over the past decade, from 207lbs(at 5'7") carrying gobs of muscle and a good bit of fat, to ~170 while having a lot less of both. What hasn't varied is that I run a good 15F warmer than average based on EN ratings and clo values.
I'm curious about the why, but really have no idea.

 

[Wanderlust073]

A layer of fat retards the loss of heat from the body through the skin. More fat, slower/less loss. Literally how everything else being discussed here (bag, liner, pad, hat, gloves, etc) works - slow the loss of body heat to the environment.

Perceived level of comfort is one thing, but basic thermodynamics is the same for everyone. Wether piling layers on or wearing a body blanket carefully woven from years of pizza and beer, more insulation means warmer body.

 

[McKee80]

There is some great info in this thread! I really felt I had my sleep system dialed in last trip with my new quilt and foam pad, slept toasty warm. But, it was probably this

A layer of fat retards the loss of heat from the body through the skin. More fat, slower/less loss.

 

[Wanderlust073]

There is some great info in this thread! I really felt I had my sleep system dialed in last trip with my new quilt and foam pad, slept toasty warm. But, it was probably this

The R factor of pizza and beer can not be overstated.

 

[Pianomover]

Thanks for all the feedback. I’m going to get a liner but just not expect as much from it. The suggestion to layer up just doesn’t work for me as I thrash in my sleep so that additional clothing just ends up a twisted mess. I am going to follow the suggestion of an additional quilt / throw. I’m regretting having lost 70 lbs now (not really)
Thanks to all.

 

[blueeyes]

Not sure how bodyfat(or muscle mass, for that matter) figures in. I often wonder if it does at all.
Women typically have a higher bodyfat percentage, yet also typically sleep colder.
My body composition has varied wildly over the past decade, from 207lbs(at 5'7") carrying gobs of muscle and a good bit of fat, to ~170 while having a lot less of both. What hasn't varied is that I run a good 15F warmer than average based on EN ratings and clo values.
I'm curious about the why, but really have no idea.

I have an ample amount of fat layer yet sleep ridiculously cold any time I camp. Yeah for being a women. I have learned to go to bed before my feet are so cold sticking them in hot water won't warm them up. Wool socks are amazing. Something better than a beanie on top of my head is helpful. I like the fleece buffs. They also double for blocking out light if I don't want to get up when the sun comes up. I can wear them around my neck or on my head. I sleep in long John's still looking for the most effective pair. May have to try the Capilene.

Insulated pad is must for me in cold or hot weather, I also prefer the wide version. I don't understand sleeping on a pad my shoulders barely fit on. I recently upgraded to the new big agnes version because my old one the valve finally died. I am impressed so far. Easy to blow up and deflate and more comfortable than the Kylmit I bought. Seriously hated that pad. The V shape baffles suck. I can feel every lump.

I have tried sleep liners and they suck. I get all twisted in them in the sleeping bag. Talk about claustrophobic tendencies. I do think for colder temps I may try the quilt over the top. When I car camp I have a delightful wool blanket I use. That is not practical for backpacking.

The heated nalgene bottle has saved me more than once. I don't feel the heat from the hand warmers as much as I do the hot water bottle I can hold against my chest. I can warm cold feet up with hot water bottle faster than those tiny foot warmers.

My puffy will be put on if too cold. Along with whatever pants I have if needed.

It is trial and error in my opinion as to what is the best sleep system. But after much experimentation I have finally learned what essentials I need at different temps. I think the coldest I have slept well tried sleeping was Mammoth Yellowstone in the teens. I wasn't adequately prepared and thankful for the heated bathroom. Where I stood in my sleeping bag boiling water to put in a nalgene. Lesson learned from that trip don't put the nalgene directly against your skin. I warmed up but it left some red welts for a couple of days. I really didn't think the bottle was that hot.

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[Tipi Walter]

I used to use a sleep bag liner back in the 1980s and as Blueeyes says, they suck. Liners look good on paper as the numbers seem right but in the field during a taste test they suck---because they are overly "cocooning" and restrictive inside an already zipped up mummy bag. A mummy bag by itself is already tight enough---hate adding another layer just to get all twisted around and difficult to unzip from the bag and emerge for a 3am pee break. I toss and turn alot.

The solution to the liner dilemma is simple: Upgrade to a warmer bag and the best down bag you can afford, i.e. Western Mountaineering or Feathered Friends or Valandre etc. If you need a liner you don't have a warm enough bag. If you need to add a hot water bottle you don't have a warm enough bag. If you need to wear all your clothing and zip up tight and get smothered you don't have a warm enough bag.

If you expect 20F---get a 0F rated bag. You'll thank me later.

One big bonus of going overkill is this: On a long winter trip with a subzero bag---you can use the bag 80% of the time as an unzipped quilt---and then when things go south you have the option to zip up and get Mummified. You'll be at the cutting edge of both worlds---the fanatics who praise quilts---and the old geezers who swear by the down mummy bag.

 

[Pianomover]

I used to use a sleep bag liner back in the 1980s and as Blueeyes says, they suck. Liners look good on paper as the numbers seem right but in the field during a taste test they suck---because they are overly "cocooning" and restrictive inside an already zipped up mummy bag. A mummy bag by itself is already tight enough---hate adding another layer just to get all twisted around and difficult to unzip from the bag and emerge for a 3am pee break. I toss and turn alot.

The solution to the liner dilemma is simple: Upgrade to a warmer bag and the best down bag you can afford, i.e. Western Mountaineering or Feathered Friends or Valandre etc. If you need a liner you don't have a warm enough bag. If you need to add a hot water bottle you don't have a warm enough bag. If you need to wear all your clothing and zip up tight and get smothered you don't have a warm enough bag.

If you expect 20F---get a 0F rated bag. You'll thank me later.

One big bonus of going overkill is this: On a long winter trip with a subzero bag---you can use the bag 80% of the time as an unzipped quilt---and then when things go south you have the option to zip up and get Mummified. You'll be at the cutting edge of both worlds---the fanatics who praise quilts---and the old geezers who swear by the down mummy bag.

At 6’8” and 270lbs my problem is I can’t take full advantage of a typical large long bag. If I cocoon fully I’m tight head to toe like a foot in a too small shoe, open it up and my shoulders are above the closure. I’m looking at custom bags but the $$ are too much for me. I just got a liner and look forward to trying it, I don’t need much more from my bag just an edge against the parts of my body that are exposed. Continued thanks for the suggestions.

 

[Bob]

i don't use a full mummy...hate them... I have used a silk cocoon liner for years.. . and they DO work in my experience adding about 5 degrees., and they help keep oils off my sleeping bag ...meaiing less cleaning.. .
Both sides experience need to be heard about for sure. Individually it needs to bedecided themselves.. They are cheaper than a new bag.

 

[Miya]

I use the Sea to Summit fleece liner and don’t feel like it actually helps me. I am still cold all the time.
Investing in a warmer sleeping bag has helped and I have been leaving the liner at home.

 

[Tipi Walter]

Bob---if you don't use a mummy bag---and I assume we're talking about cold weather sleeping since we're talking about liners---what kind of bag do you use? A big rectangular bag?? Do you car camp or backpack? Just wondering.

And Miya---Reflects pretty much my thoughts.