Bag Liner

I can't remember if this topic has been discussed on here before or not. Do bag liners such as this really add more warmth to the bag? Or they just mostly keeping human's body oil from seeping into bag?

I was thinking, if I was to take my sleeping bag (the 15 degree one) somewhere cold and the temperature would be right around the bag's comfort rating. And say the temperature drops 5 degrees below comfort rating, would a liner really boost the warmth? I wouldn't expect a 40 degree bag compared with the liner I mentioned above to keep me warm in 20 degrees weather, but a 15-20 degree comfort rating in say 10 degree weather I wondered if it could make a difference?

I'm one of the idiots that bought one of those liners. First they don't seem to add any warmth, second they do a poor job of protecting a bag from dirt, oils, sweet, mostly because the fabric is so thin and permeable. Lastly I found myself tangled into a knot when I used it. Don't waste your money!

I'm thinking that taking an extra set of long johns (one weight lighter than you wear during the day) would get you to the same place temperature-wise, weight-wise, and cleanliness-wise - and provide more versatility than a liner.

Personally, I never plan to "stretch" the range of my sleeping bag by relying on my clothing. I normally sleep in the clothes I've worn during the day (I usually don't end up the day too dirty.) My insulating clothing, usually worn only at breaks or in camp, consists of down pants, down booties, down mittens and hooded down jacket. This is my safety margin for sleeping, in case it gets colder than predicted. If I'm headed into 25-degree weather, I take my 20 degree bag; I don't take my 30-degree bag and plan to stretch it by wearing my clothes.

That kind of thinking saved me from a very cold night. Temperatures were never predicted to drop below 20, so I took my 20-degree bag (Western Mountaineering, so it's a conservative rating.) When the bottom fell out one night, and it went to near zero, my extra clothing kept me nice and toasty when the bag started getting chilly (which actually happened around 15 degrees, confirming the conservative rating.)

Suppose it would help a wee bit--maybe five degrees?--and might be more interesting if it's an IR reflector (I can't tell from the description). But without a way of anchoring it inside the sleeping bag, it will probably TRAP YOU FOREVER. I've found liners tend to go one direction while I go another and the bag goes a third.

I think bivy/overbags are better than liners, unless we're talking about vapor barrier liners, which is a whole different ballgame.

Cheers,

Thank, guys.

There is no reflective coating, it is simply a light weight hollow tube woven sleeve. Much thinner than a standard cotton sheet.

Thanks. I didn't see anything shiny in the pics but didn't want to presume.

Cheers,

Tried one of those silk liners for a few nights; took me several minutes each morning to get untangled. No apparent increase in warmth, and no apparent decrease in warmth when after a few nights of this nonsense I tossed the liner in the nearest trash can.

Like Glenn, I use my insulating clothing if the temp goes below what my sleeping bag can handle. I also use my non-breathable rain gear as a vapor barrier over my base layer when it's freezing or below. That really does add appreciable warmth and keeps my "insensible perspiration" out of the sleeping bag insulation. Any insulating clothing added goes outside the rain gear so it won't get damp from my body moisture.

You gotta hate the silk stuff. It is too thin so it won't provide much warmth. The only way it produces heat is through fast friction which doesn't happen a lot while sleeping.
-Nate-

I've used the Coleman Fleece bag as a liner, and as a blanket on top of my bag and it does add warmth. I've also used an emergency blanket on top of my bag on nights when the temps dropped below freezing. They both worked pretty good.

Personally I feel my bag liner made a significant difference in temperature but the experienced difference may be due to my using a relatively cheap bag. My bag is a featherlite 0° bag and in 37 degree weather I felt cold but with the addition of the liner I did a couple nights of 20° with no more discomfort. I also think the bag liner cut down on draftiness in my bag and kept my skin from directly contacting any zippers. My two cents is that I will happily pack the extra few ounces as I feel I get something in return.

I don't use a bag liner. I wear my Capilene and that keeps the bag clean, or at least cleaner than if I wasn't wearing it. I do have an overbag, an MEC Emperor Penguin and that does add warmth since it has its own insulation. I also have a light bivy sack. The three together is a bit of a hassle, so I now have a warmer bag.

I've used this product just as you mentioned, and it's performed about at the limit you set- 5 degrees. I've also used it by itself on cool summer nights when I needed just a light covering, when it was 65 or so. It probably outperforms another layer of clothes for a warmth to weight ratio, but the clothes will probably have a greater gain in lowering the comfort range. As a 10 oz. sleep system for the summer, it's OK. We used it this past fall on a trip in the Sierra where the average night was around 22 and we had brought 30 degree bags. I wore a fleece jacket and my wife used the Reactor. We both slept well. I found you need to roll the liner down when you get out, if you wish to return to it in any quick fashion. Once I learned that, it was no problem getting back into it.
I'll use it occasionally for a slight boost and by itself as a very lightweight sleep system. I will never use it to supplement more than 5-7 degrees, though. IMO, their claim is a little exaggerated.