Mummy bag liner?

[Paul]

I'm looking to extend the range of my REi Subkilo to below freezing, probably a true 20 degrees.

What do you recommend? Doesn't have to be UL, but warm at least. Fleece, silk, etc.?

Sea-to-Summit has a nice looking Thermolite liner at at 8 oz.

The REI MTS liner looks comfy, 11 Oz though. Hmmmm.

[Reality]

I used a down quilt (rated about 35*) last week when it was 20 deg F. outside. I wore a lightweight base layer and stayed quite warm.

If you can make it work for you, using a lightweigt base layer (or thin insulation layer -- e.g. microfleece) would be more versatile (multiuse).

If not, a bivy or liner will do the trick, depending upon the shelter/location...

Have you checked the local outfitter? One of the stores that you and I frequent have a few to choose from.

Reality

[willspower3]

With temps down to the low 30's, you would probably want a warm jacket and pants for around camp. You could wear fleece or insulated apparel to bed and add a good 15 degrees to the bag depending on the warmth of the clothes. I am getting a Montbell Thermowrap Parka when $$$ is friendly to me. 12 oz for 2.7oz /yd insulation- a great warmth to weight ratio. I have found that putting arms in the main body of the jacket is warmer if the jacket is roomy enough.
I also like silk/VB liner combo below freezing. I have some Reflective silnylon coming in this week for that purpose, and it should add 15* for 5 oz, if all goes well. Close to 20* with the silk liner hypothetically, but we all know how that goes. Good luck.

[atomick]

Y'know, I was in the Sierras recently with a Western MountaineeringMegalite (down, 30 degree rating) and it was coooooold one morning, same temperature range you are mentioning. By simply layering clothes it was really quite easy to lower the comfort rating by 10+ degrees F. Willspower3 had already suggested this. My personal combo was both a Marmot DriClime windshirt(for less cold nights) and the Primaloft-filled Redpoint Jacket from The North Face. Now I've traded both (weight-wise) for a Western Mountaineering Flight Jacket.

The upshot here is that, sure, you can extend your bag's range with a liner. But experience has shown me that it's more weight-efficient - and yes, even more comfy! - to extend the range of your bag by wearing more clothing, which you're probably already carrying!

Of course, take note that if you wear layers to bed, don't let your bag get too restrictive - air's the best insulator and if you compress your insulation it'll work less efficiently. "Loft" is everything, IMHO. That's why, even as a 6-foot, 160-lb male, I got the "bigger person"-cut Megalite bag...great for layering at night without compression of loft.

FWIW,
-Atomick

[PBF Support]