August 28, 2024

Fluff

Back in 2021 I wrote some things about layers like the Arcteryx Atom and Patagonia Nano-air. What makes these interesting is that they are synthetic insulation that can be used alone as well as under a shell. They are also well suited for wear during high output activities such a trail running or hard hiking in cold weather.

I carry them because they are light and reliable in wet conditions.

Down

"What about down?", you may say. Down is great until it gets wet. It can get wet by getting rained on, by being stowed in a pack that gets wet, or by sweat and condensation during high output exercise. Down is fussy. Synthetic is robust. If things get ugly, you can rely on synthetic, but down may let you down. We are talking about hypothermia in cold and wet conditions.

Some pieces

I have both an Atom LT and a Nano-Air. I consider both as relatively fragile. I might wear them by themselves when hiking if I was on a well used trail with little or no risk of rubbing against branches and such -- but for any kind of off trail activity, I would want them under a shell or I would want something else.

I am tall (6'1") and thin and I find that Arcteryx has a much better idea about what fits someone like me. It has always perplexed me that Patagonia aims for a person with a couch potato physique, wide in the middle with short arms. Aren't we making gear for outdoor athletes? People say that the Proton has an even slimmer fit, so bring it on!

To be more specific, my size medium Atom LT from Arcteryx is a perfect fit. With Patagonia, I can buy a size medium vest and it is perfect on my torso. When sleeves enter the game I am forced to buy a large and accept some useless volume around my torso. 

Arcteryx Atom LT    13 ounces $300
Arcteryx Proton LT  14.6 ounces $350
Patagonia Nano-Air  14.1 ounces $329
Patagonia Nano-Puff  11.9 ounces $239
Patagonia Nano-Air Light  10.5 ounces $249
Arcteryx Atom LT vest  8 ounces $200
Prices shown are full retail. Sales and deals can always be found.

The vest

Note the Atom vest above. I got mine on sale as an impulse buy and it is one of my favorite pieces of gear. I love vests in general. I like fleece vests because of their lack of arm bulk in combination with core warmth. I have a Patagonia down vest that packs more warmth for its weight and size than anything I own -- but I don't often carry it except when backpacking. The Atom vest is a nice balance between being light and small and reliable, not to mention warm. It vanishes in a day pack and often can make a difference.

Nano-Air versus Nano-Puff

The Nano-Air breathes better (hence the name) and is good for activity. The Nano-Puff is more suited for sitting around camp and staying warm. That is the party line anyway -- looking at price and weight you would think the Nano-air would be warmer. The Nano-puff is intended to be worn on its own and has a more durable wind resistant fabric. The Nano-air is intended for high output activity or use as a mid layer.

The Nano-Air light is new (since my purchase in 2021). It has R1 fleece panels which would seem to be an imitation of the Arcteryx Atom, but more breathable.

Proton vs Atom

The Proton breathes better. The Atom is better in the wind. A twist is that the Atom has fleece side panels and a cold wind can push through them. So they say, I have not been bothered by it.

This choice between the Atom and Proton is a new one as of 2024 and the call is hard to make. Another way to look at it is that you can't go wrong with either, so get whatever you find the best deal on.

Someone said this:

Here is a nice review of the Atom:

Here is what a fellow on Reddit said:

I have both (2021 Proton and 2022 Atom). They fit differently. The Proton is shorter and slimmer, but conversely the arms are more articulated so reaching overhead doesn't pull the hem up as much like the Atom. It makes sense as the Proton is designed for climbing. The Proton is not nearly as wind resistant as the Atom but even the Atom isn't wind terribly resistant. Honestly the fleece side panels on the Atom are a non factor. I've never wished they weren't there. FWIW the Atom looks better in causal use than the Proton. Honestly I would consider an an Atom AR as a warmer jacket that can stand up to some (but not heavy) wind. The Proton for me is an active mid layer or active outer layer on calm but cold winter missions. I think there are more comfortable pieces for daily use. I woudn't want to be wearing either in low output in sub 40 F temps. I was wearing my Atom LT today over a Kyanite AR, and under a 3L shell and it was 33 and it felt chilly. Proton has more insulation than the Atom in the core and is slightly warmer when there is no wind.
I should also note that Arcteryx has different variants of the Atom. There is the Atom LT, as well as the Atom AR, and perhaps others (Atom SL?). With Arcteryx gear the letters are very important. The same name with different letters can be a totally different piece of gear. You have been warned.

Fluffy jackets and wind

I find myself a bit perplexed by peoples comments on wind. I am glad when I can wear the Nano-air or Atom by itself, but when the wind picks up and I get chilled, I pull a shell out of my pack and put it on. I expect this. You aren't going to find me out without a shell. How far I can push one of these to keep me warm in the wind is of little or no importance.

The Patagonia R1

This is a different game, but I have to mention it. You can get a lot of mileage out of an R1 along with a Patagonia houdini. If you expect rain perhaps, take an actual rain shell. 
Patagonia R1 hoodie  13 ounces $180
I have the plain R1. Given the move to the new R1 "air", there is a good chance of finding the original and very solid plain R1 at a sale price.

Actually I have several R1, both in Hoodie and non-hoodie form. I often sleep in an R1 hoodie in cold weather. Being fleece, these are not delicate like the fluff jackets described above. Everyone should own at least one R1. They are indestructable classics. The new R1 "air" uses a different new tech fleece that is supposed to be warmer for the same weight. In really cold weather, an R1 with an Atom LT over it, and a shell would be pretty effective.

Have any comments? Questions? Drop me a line!

Tom's backpacking pages / tom@mmto.org