Wool Baselayer — Good for How Many Degrees of Warmth?

In a bag? Likely not. They are tested with thermal underwear. Here is an excerpt: “three-layer, cotton (42%) and polyester (58%), knitted fabric.” I believe the notation also included: “…thermal resistance of 0.051…0.046m2K/W…Knee-length socks were also used…”

Basically it says that a heavy weight set of long johns and heavy weight long socks. There is a 15% variance allowed during testing, too. While the EN standard allows you to compare bags fairly well, it does not say a lot about the exact temperature you can be comfortable with. Really, it errs on the side of manufacturers to get them, keep them using a single standard. So, depending on how you sleep, what type of long johns you use, whether you are in a tent or not, extra ground insulation, and the 15% variance, a bags temp rating could miss by 10-20F, anyway.
Example: I generally sleep cold. I often sleep in lean-tos. I often go out with a EN rated 40F down bag. With a sweater, down jacket, long-johns, two pair of socks, and hiking cloths, sleeping on my torso pad over a NeoAir, I could push my comfort limit down to ~25F. And likely my survival limit to about ~10-15F(never tried it.) In summer, I can open up my bag into a quilt and find it comfortable to about 55F with a light set of long johns, no socks, and removing my foam pad. So, there is a wide variation.

No… there isn’t.    Basically, everyone sleeps differently and everyone sleeps differently at different times.    As I’ve aged I sleep colder.   If you are exhausted, depressed or dehydrated you will sleep colder and humidity levels and wind change the situation too.

I’d forget trying to match an exact temperature to an exact level of clothing.  Generally, you will carry long underwear anyway (I do year round) and you will always wear them in your bag.   You will have additional clothing that you can bundle and hopefully a good hoody and hat that you can wear.   Buy a sleeping bag or quilt that is generally rated for your expected temps and use a good pad.    If you find it is too cold you can either supplement it with a down jacket hoody or sell it on the gear auction and get a heavier one.

Everyone runs different so it’s hard to say.

You’ll have to experiment to find your regulating sweet spot.

I sleep in almost nothing usually down to about 20ish. I typically don’t sleep outside in much colder conditions.

I always sleep in my merino baselayers and/or silk tops and use a WM -15F rated winter bag.

**  At 20F I will sleep under my bag unzipped like a quilt wearing my merino leggings/socks and long-sleeve silk top.

**  At 10F I will do the same but wear my leggings with silk top under my two patagonia capilene tops—with the thermal hoody-hood over my turtle fur fleece hat.

**  At 0F I may or may not zip up the Puma bag—if unzipped I’ll put on my arcteryx fleece jacket over my capilene and sleep without constriction.

**  If it’s really cold, like -10F, I’ll zip up the bag and wear my leggings with socks and my capilene tops with hoody and TF hat.

Thanks for everybody’s replies.  Last June, I hiked all 68 miles of the Skyline Trail in the Santa Fe NF.  My system then, was a Marmot Pounder bag (not a very good bag), Klymit Inertia X-Lite air mattress, and I slept in merino wool socks, fleece running pants, fleece running shirt, gloves, beanie, and balacalva.  I was too cold.  Now, I’ve learned that Marmot was full of BS when they rated that Pounder bag as a 40 degree bag.  The EN 13537 lower limit on that bag is 54 degrees!  No wonder I froze at night.

This August, I’m hiking all 72 miles of the High Sierra Trail.  I’m going to have a much better bag — something with a much better EN rated lower limit.  As to whether a wool baselayer in the 150 g/m2 range will be sufficient for me, I guess I will just have to try it out and see (like others have suggested).

Thanks!

One other factor to keep in mind with wool baselayers is that they don’t dry as quickly as synthetics, and a damp layer is Enemy #1 where heat loss is concerned.

First it takes a lot of energy to vaporize moisture — energy provided by you, which is not warming your quilt/bag — and it also robs energy by direct conduction to your sleep mat.

I ditched all my Icebreaker midlayers for capilene for this very reason—Merino is heavier and doesn’t dry as fast.  Except I still use my comfy leggings for sleeping and/or cold weather hiking under shorts.

The main purpose of a base layer is to wick moisture away from your body without chilling evaporation .

The lightest insulation you can bring to keep you warm when sleeping is the down in your sleeping bag/quilt. I bring a bag or quilt to handle the night time low temperature I expect. Should temps get unexpectly cold, then I wear my insulated garments, assuming they are dry.  On every trip my most important gear choice is a sleeping bag or quilt to match the weather conditions. Better to bring too warm a bag or quilt, which can easily be vented than be cold and get a poor night’s sleep.

I agree with Nick. If you get into R1 or Power Stretch level “super” base layer/mid layer or something like high loft fleece you are getting some real temperature boost. Nothing wrong with sleeping in your windshirt or puffy. If you are cold, wear it all!

Yep, I love the R1 grid pullover over an OR Echo T. For me this has proven to be a warm and fast-drying combination. Combined with a MB Versalite it provides an amazing amount of warmth and flexibility (esp ventilation) for the weight.

For me, one of the main reasons I prefer wool is because of its ability to not stink horrendously, after many days of wear.

People’s body chemistry is variable… Much less of a problem for me, but clearly not so for others as I’ve read many times. A guy with whom I used to do mountaineering trips stunk to high heavens no matter what he was wearing… but I got used to it somewhat and tried to stay upwind of him.

The backcountry washing machine (1-gal ziplock, water, few drops of Dawn) works well for me when water is plentiful and weather permits.

Otherwise, stink won’t kill ya. ;^)

I think Nick’s idea is good – base layer is to wick water away from your body.  And absorb body dirt and oils so it doesn’t get into your sleeping bag and degrade the down.

Doesn’t add significant warmth