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The cold world of skimo & alpine climbing

The cold world of skimo & alpine climbing

Sunday, December 30, 2012

Synthetic Insulation 60g to 100g

Sweaters and LWT Belay Jackets

The typical question:

"I will climb Rainer this  Orizaba, Kili, then Aconcagua!
 What do I need for clothes?"

Here are some thoughts on a well proven "systems approach" that you
may have not had.   It is a multilayer and multi use cold weather system
 based at least two garments.  One garment with  60g insulation and the
 another with 100g insulation.   The bench mark Patagonia DAS belay
 jacket is 170g insulation by comparison.

For really cold temps I have used up to 4 lighter layers or 280g of
insulation, plus the resulting eight layers of nylon shell material that
comes with it. 3 layers @ 60g and one at 100g. Surprised actually, at
just how easy/well the system works.  And how easily regulated for
mid winter technical climbing at altitude, a cold bivy, a quick ascent
of Rainier in summer or Fall/Spring alpine climbing.   One garment
at a time makes the buy in easier and the mutilayers should give you
 a lot of use/durability over the long haul.

I have a good many choices in the closet and find myself actually
using variations of this system almost full time these days. Simply
because of what is available for a "system".  It is the lightest,
breathes the best and is the easiest to pack cold weather system I
have used.   Generally 2 layers of 60g. When it is really cold I'll
add the 100g as a third layer.  May be even a fourth for an open bivy.

Sure a single thick down jacket will be the warmest and breath very
well.  Might even be the lightest.  But they are fragile.  Get down wet
from sweat and you loose much of the insulation.  Add a water proof
 shell and you limit the breathability.  One big warm layer and you
don't have a lot of options for temperature control.  There is defiantly
a place for down garments and even multiple layers of down I think. 
But for technical climbing I suspect multiple layers of synthetics offer
 a better choice for most of us.

No where was Alaska mentioned in the opening quote. Nor was it
addressed by me originally.

I've done multiple trips to the Alaska range. For time spent (45+ weeks)
 almost a full year on the glaciers there. Half of those trips included the
 summit on Denali. All but one were originally to more technical
objectives first, just not very successful. Trivial record compared to
many climbing there now.   I've taken down jackets to Alaska twice.
 A synthetic bag once.

Below, you are looking at an open bivy on Mt Deborah, Alaska using
 both, 4000' off the deck.. We did three open bivies that trip. Not the
first or the last with that or other combos. But not once did I  "sleep
 like a baby".

But not taken a down jacket or a synthetic bag to Alaska since '80.
Dated technology in many ways now for what I was trying to do.
None of my partners or myself have had a cold injury...on any
mountain while using synthetics. Would I take Down again now?
Sure, depending on the objective..

There are some pretty amazing synthetic stand alone jackets available
these days, the Patagonia DAS, The Arcteryx Duelly or Fission SL,
The MEC Tango among many. "Stand alone" meaning the biggest
and most insulation in a "belay jacket". They are sized to go over all
your clothing. Some nice down choices in that category as well,
Eddie Bauer XV, the RAB Nuetrino, Mtn Hardware Nilas and the
Naronna Lyngen. Specific combos of lighter weight insulation
offer even more choices.

Back to the question?

"At some point I'd love to get up Orizaba, Kili, Aconcagua, and
wondering if jackets for something like Aconcagua is going to be
overkill for a Rainier jacket?"

Polish route on Colfax n Feb '10.

Mid weight down jackets like the Narrona Lyngen pictured above
can be a good choice for climbs like Aconcagua and warmer

The experience of using a 60g and 100g weight garment  seems
imo to be a better *combo* for the mountains listed, having
on 3 of the 4.

The coldest I have ever been in the mountains was in the Alps in
the winter of  2010/11.    Great technical climbing just a 20 minute
tram ride above Chamonix and only minutes from a latte and a
nice salad.

May be I should have actually zipped up that last 100g layer. In
Alaska I probably would. Well may be I would.

In the picture above, my base layer is a R1 Hoody.  From the R1
out I am using a  Atom Lt @ 60g, A Patagonia Nano Pull Pullover
another 60g layer (which are a part of my "action suit") and
finally a Atom SV @ 100g.  For a total of 220g.  I had stared
the climb in a single 60g layer and as the day got colder I
added layers.

Synthetic garments layer well. They will dry from body heat
alone from the inside out.    I have not found adding down
layers to a pile garment of any sort as effective transporting
moisture.   Where a layer of Priamloft 1 does very effectively.

One of the reasons the Patagonia DAS @ 170g is likely the
most widely used synthetic belay jacket made.  Helps of course
that Patagonia was the first to market a belay jacket based
specifically on Mark Twight's ideas and writings in

I think anything over 100g weight insulation as your last layer
is generally over dressing for technical climbing in the US and
Canada, short of the typical Alaskan climbing season and
Canada or the Alps mid winter.

Lucky for us there are a lot of choices in my preferred
combinations of 60g and 100g insulation.

Eddies Bauer:
Has two in the First Ascent Series.  The ever popular
Ignitor @ 100g and the newest hybrid on the block with
40g of Primaloft 1, the Accelerant Jacket.

Offers a number of garments in these weights.  The Nano
Puff Series @ 60g and the 100g weight in the Micro Puff Series.

Has the Atom series..Atom LT in the 60g and the Atom SV
 in 100g weight.

Mount  Bell:
Has the Therma Wrap BC which is unique with insulation 
80g Body and 50g sleeves
The Therma Wrap Pro is 80g though out  

The jackets from RAB that  I looked at are the Xenon @ 60g
through out and the Alpine Generator with 100g in the body
and 60g in the arms and hood.

But as much as these 8 jackets look the same..they clearly are
not.  Patagonia uses a Primaloft 1 and Priamloft Sport for
insulation.  There is a significant difference in insulation value
between the two Primaloft offerings.  RAB is using Primaloft 1,
the gold standard for synthetic insulation by most accounts.

Acrteryx offers the garments listed here in Coreloft.   By Arcteryx's
admission its Clo rating is 5% less than Prmaloft 1. 

Mont Bell is using their own Exceloft synthetic insulation. 
"Exceloft a combination of 8-denier compacted polyester tubing
with extra-thin, 0.7-denier polyester thread makes the insulation
remarkably compressible. In addition, Exceloft absorbs very little
water, making it highly resistant to saturation and extremely
quick to dry."  And my take from all that is either a combo
of the Exceloft and their shell materials or just Exceloft makes
a warmer garment for fill weight than Primaloft.  But I have not
seen Clo numbers to  prove me right or wrong.  Just a educated
guess from using all these garments as they were intended and
in a controlled environment simply for this comparison.

This came in from a reader after I first published the comparison
on,  Thanks Sean!

Montbell's Winter 2012 catalog,
"Compared to some synthetic insulations of equal weight,
EXCELOFT achieves the highest Clo Value (a measurement
of thermal
insulation)."  (page 16)

Clo and fill weight?

Synthetics are measured by grams per square meter of fill. •60 g/m²
Double the thickness of the insulation and you get,  •120 g/m²

Weight has nothing to do with fill power or Clo values (which is
basically an esoteric heat retention measurement for the human body).
 Grams per square meter is just a measure of physical weight.

Which brings me to the real part of the story when you make
comparisons.  The outer shell materials are obviously really
important for the intended use.  As is the detailing and construction
of the garments. 

The combos I have used and like are a combo of pull over and
and zip front.  Generally I want a hood on the 100g layer but a
hood on both is welcome as well.  Although I think at times
the 60g garments can be really versatile in both versions, with
or without a hood.   40g, may be even more so.

Weights in a Men's Large on my digital postal scale:

Eddie Bauer
Accelerant Jacket 13.5oz
Ignitor 20oz


Nano Puff  Pullover 10.5oz (no hood)
Nano Puff  Hoody 13oz
Micro Puff Hoody 18oz

Atom Lt Pullover (vented- no hood) 10.5oz
(see the next review for the 80g/m Aphix Hoody)
Atom LT Hoody (vented) 14.6oz
Atom SV Hoody 18.6oz

Mont Bell
BC (no hood and vented) 13.1oz
Pro Hoody 16.8oz

Xenon Hoody 11oz
Alpine Generator Hoody 20.7

How about a direct comparison of the 60 g garments no vents?

Accelerant Jacket 40g PL1 13.5oz  (note this is 40g PL1 not 60g)
Nano Puff Pullover 10.5 (no hood)
Nano Puff Hoody 13oz
Xenon Hoody 11oz

And 60g garments with vents.
Atom LT pull over (vented) 11.oz
Atom LT Hoody (vented) 14.6oz
BC (no hood and vented) 13.1oz

Again as close as the weights are you have to make sure you are or
are not getting a hood.  And if the garment offers a stretch fleece
under the arms for venting.  Both will add weigh to a garment. 
And depending on your requirements may be some usefulness.

The side venting on a shelled and lightly insulated garment is most
easily identified in my mind with the Atom LT.  I started using the
Atom series several seasons ago and have written about it many
 times in the last 4 years.  Eddie Bauer has take this to the extreme
in the Accelerant Jacket with 40g weight  PL1.  Mountain Hardware
 offers a version as does Mont Bell among others.  For an active
layer where you also need some extra warmth I think the idea is
brilliant.  Enough so that I have stopped using soft shell jackets
changing out for a 60g layer of synthetic insulation with venting
and a good hood.

Aton Lt in use @ -25C
Ignitor Jacket 20oz
100g PL1  Lightweight 1.25 oz  20-DENIER 100% Ripstop nylon
With StormRepel® Durable Water-Repellant Finish

Micro Puff Hoody 18oz
" Lightweight, 1.7oz 30-denier 100% recycled polyester ripstop,
windproof shell made of recycled polyester and treated with a
Deluge® DWR"

Atom SV Hoody 18.6oz
Gossamera™—100% Nylon ripstop fabric with water repellent
coating DWR

Pro Hoody 16.8oz
"Ballistic" nylon is one and a half times more abrasion resistant
than other similar weight fabrics and boasts three times the tear s
trength of nylons that are almost 20% heavier. 100-wash rated
POLKATEX DWR treatment."

Alpine Generator Hoody 20.7
30D triple rip stop Pertex® Endurance outer and a Pertex®
Quantum 20D rip stop lining

Fit?  Fit is obviously such a personal thing.  I am 6'1" and 190#.
Here is how I have used these garments and my comment
on the fit in that use.

Accelerant Jacket:  It is a slim fit and feels like a more traditional
sweater as there isn't much too it.  But warmer than you would
think for the weight and good wind protection as well.

Ignitor:  Is a full zip and light weight sweater with a lwt fleece hood. 
Warm enough and wind proof enough to work as a layering piece
or as outer wear.  Interesting garment that should draw a lot of
attention once people learn how to use it in their own clothing

Nano Puff  Pullover:  I generally use this as an over shell for
the Atom light.  It is a big and boxy cut on me.  Nothing
flattering but I love the weight and warmth of this jacket/ sweater.

Nano Puff  Hoody: This one is again big and boxy for the size
on me.  It is a little heavy and I don't like the hood size.  But for
 the weight and versatility of a full zip and a usable hood
others might love this one.

Micro Puff Hoody:  With Primaloft Spot this one holds little
interest for me but then the price point reflects the use of a
less insulation.  Same issues with Patagonia with fit and
pattern for me on this one.    

Atom LT Pullover:
Atom LT Hoody:
Atom SV Hoody:

These I'll admit are go/to pieces for me.  They fit like they were
 designed to layer together and every detail is almost perfect on
both jackets.   The Pullover is a slim fit that I use as a wind
proof sweater. Awesome hoods by themselves on the jackets
or in combo and over my Petzl helmets, which generally
 impresses me.   I have zero complaints on these two after
several years of use in some really cold conditions.  They
have a tailored athletic fit which I really like and never
bind while climbing.  I simply love the combo.

BC (no hood and vented): I like the option of not having a
hood on occasion.  And I really like the vented style garments.  
The 50/80g combo also added a garment here that is significantly
 different in warmth.  I have to look for places to use it and then
 decide why I should instead of an Atom Lt.  But it is good
enough to make the effort.
Pro Hoody:  This is a jacket that made me realise I really am
a gear snob.  For it's 80g weight it seems warmer to me than
the Atom SV by comparison.  I really like the pattern and
detailing.  The hood (which will take my helmets) and knit
 cuffs stand out.  As does the pattern.  It is athletic and very
fitted.  This has become one of my very favorite 100g
jackets...even though it is only 80g weight insulation. 
Go figure!  Big surprise to me all round and a very
pleasant surprise at that.

Xenon Hoody:  This is a sneaky little guy.  It is not sewn
through like the Patagonia 60g Primaloft.  And it is two
ounces lighter.  It has a Pertex QuantumGL® 10 Denier
shell fabric inside and out.  There is more to this one than
easily meets the eye.  My only down side is the hood is good
only under my huge helmet.   The shell alone and the way
RAB has done the insulation makes this one sort of  "out
of category" in a very good way.  It has replaced my
Atom LT on windy days and dropped a few ounces
in the process.

Alpine Generator Hoody:  If the Xenon is "out of category"
the the AG is a ringer here.   No one else using  a Pertex®
 Endurance outer and a Pertex® Quantum liner.  The hood
is the best of the bunch imo and the Acteryx hoods are
VERY good.  The sizing spot on for layering.  This jacket
seem to me to be a specific built belay jacket with no
compromises.  There are no bad 100g jackets listed here
but the AG is a step above all of the ones I looked at in
this review.   It is as obvious and as simple as that.   Be
sure to check your sizing. I've found RAB to run a little
on the small size across their range.

The point to the conversation here is that as singles or as
combos synthetic garments for climbing even in the harshest
of conditions can easily be justified.  With the right combination
 of garments you could easily use a lighter one listed here for
a chilly day cragging or a combination of several for a  speed
ascent of the Cassin.

If you ended up here by chance be sure to look at the
following review of the new (fall 2012) Acteryx Aphix
Hoodie.  Things just keep getting better!


Anonymous said...


What happened to the text? Firefox (both osx and xp) cuts off the right side of the text column or the text "continues under" the Blog list etc.

Anyway, I really apreciate the time and care that has gone to your blog. It's amazing.


Dane said...

thanks Jussi, hopefully that fixed it...

Anonymous said...

Hey Dane,

thank you very much for your thoughts.
Helped me a lot!


Jim Thomas said...

Using Safari; the right side is cut off for me as well.

Aveman said...


Have you looked at the MEC Northern Lite Ultra? The current sale price is hard to beat and it's got up to 170g of PL1. 23 oz in medium vs. 26 oz for the DAS, similar features and much, much better cut.


Unknown said...

Hi Dane
How does the FA Accelerant Jkt compare to the Marmot Variant hoody?
I ice climb in Norway and find a nano puff pullover a bit too warm under a hardshell and on top of a Patagonia R1. Ive read reviews for the Variant hoody but it gets slated everywhere.
They seem quite similar jackets and was wondering if you could help.
Awesome blog by the way.

Dane said...

Marmot is using •Polartec Power Stretch Pro. It is very cool stuff. And more (warmer) of a garment than the EB piece. Both are good just depends on your needs. And how you work either into your own system. The Patagonia Piton was easy for me to incorporate into my own clothing system so I think it is brillaint. The Accelerant and Variant much harder for me to do the same so I am less imrpressed. It will take more effort on my part before I find the real advantages of that kind of garment. But I have no doubt there are advantages to the current generation of hybrids.

Ryan said...


Do you have a feel for the breathability of the Endurance shell on the Rab Generator? It's advertised as water resistant and breathable, but I've seen mixed opinions. It would be a shame if this shell hinders breathability substantially for the sake of "water resistance" in a synthetic jacket.

I really appreciate all the work you put into your site, it's made me much more aware of the details that no one else seems to think about.


EJ said...

Hi Dane, You wrote about the Montbell Thermawrap Pro Hoody: "This is a jacket that made me realise I really am a gear snob. For it's 80g weight it seems warmer to me than the Atom SV by comparison. I really like the pattern and detailing. The hood (which will take my helmets) and knit cuffs stand out. As does the pattern. It is athletic and very
fitted. This has become one of my very favorite 100g
jackets...even though it is only 80g weight insulation.
Go figure!" I've worn the predecessor, the Thermawrap Hoody, which has the same 80g Exceloft. It is incredibly warm and wind resistant for the weight. I think part of the warmth comes from the shell material, which does a great job of trapping heat, and the cut.

Do you currently prefer it to the Atom SV, and still find it warmer than the SV or just as warm? Also, over which layers do you wear yours? Do you wear it in the same way as the Atom SV, over the same layers, and if so, what size do you wear? I'm very close to you in size.

Thank you for your incredibly helpful posts and taking the time to answer my question.

EJ said...

Hi Dane, How would you compare the warmth of the Montbell Thermawrap Pro with that of the Rab Generator? The Rab Generator is a few ounces heavier, and uses 100g insulation in the body and 60g in the arms, while the Therawrap Pro Hoody uses 80g Exceloft throughout. You've had high marks for the cut of both, and have said you felt the Montbell is even warmer than the Atom SV, and the Montbell is lighter than the Rab by about 4 ounces.

EJ said...

Is the Xenon still your preferred warmest for the weight synthetic jacket to wear under a light belay jacket like the Montbell Thermawrap Pro Hoody or Atom SV Hoody? What do you think of the new version of the Xenon, which uses different shell material? Do you prefer the old or new version of the Xenon (both of which are still available)?

EJ said...

Last two synthetic insulation questions (for today, lol): 1) Which light belay synthetic fill pants do you like? Patagonia DAS Pants (100g Primaloft, previously called Micro Puff Pants), Montbell Thermawrap Tech Pants (80g Exceloft), or other? 2) What's your current favorite warm (heavier) belay jacket (in the same class as the Patagonia DAS)? Would it be roughly the equivalent of a Rab Xenon + Montbell Thermawrap Pro in warmth, or warmer? I'm in the middle of refining my current synthetic layers and really appreciate the advice you've shared here. The Patagonia DAS is my only reference point in warmer sythetic belay jackets.

Dane said...

I don't use synthetic insulated pants generally. 60 and 100g jackets and how I layer? Pretty much said everything I wanted to say already :) I don't write about bad gear. So it is hard to go wrong with the suggestions I've made.

Nathan said...

Pardon the comment on the 3 year old article, but I wanted to ask you: what do you think of the mec socked in hoodie for. 100g piece, and the mec uplink hoodie for a 60g piece? The arcteryx looks great but the price tag is blowing my mind a little compared to these cheaper mec options