Arc’teryx Thorium Review

The name of Thorium AR has been changed to Thorium for winter 2023. There has also been some design updates: 

• A two way zipper is added, which to me is the main (and the strangest) highlight, 
• An external chest pocket is added, 
• Fit is now a little bit baggier, 
• Baffles are a bit larger (see image below), 
• Hood is now helmet compatible, 
• Amount of 750 FP down is increased from 130 grams to 140 grams,
• Made more eco-friendly. 

There has also been subtle changes in the weight (slight increase) and center back length (slight decrease). Check out the jackets database table below for more details about them. 

Thorium Parka is also just in! Here's the Thorium vs Thorium Parka vs Thorium AR side-by-side comparison page on arcteryx.com: https://arcteryx.com/us/en/compare/X000006585-bitters/X000006919-black/X000006972-figment

Even if Arc'teryx decides to discontinue the Thorium AR in the future, its second hand will live pretty long because of its popularity and durability. 

Summary

Arc'teryx Thorium is a fantastic, warm down jacket for casual use in dry areas. It's comfortable, light, stuffs into itself and is even equipped with a two way zipper. 

I wouldn't recommend it for damp areas at all though. Because it soaks water like a sponge (as all down jackets do). Don't think about it for high output activities either (fragile face fabric and poor breathability). 

FYI, Thorium isn't the only down jacket line Arc'teryx offers. There's the Cerium line, too - which is a lighter and less warm alternative to it. 

Links: 

• https://arcteryx.com/us/en/shop/mens/thorium-hoody
• https://arcteryx.com/us/en/shop/womens/thorium-hoody
• Thorium vs Cerium side by side comparison page on arcteryx.com: https://arcteryx.com/us/en/compare/X000006972-figment/X000006919-black

Warmth

Thorium is pretty warm, especially for its weight. This isn't surprising news for any down jacket as they offer incredible warmth to weight ratio. 

Check out its temperature rating below: 

When it gets soaked in water (e.g use under precipitation), not only it lets the water in, but it also loses insulating power. That's because down provides warmth by trapping air in its vacant spots, and water, as you can guess, interferes with that mechanism. 

If you'd like to read more about the working principles of down insulated jackets (or synthetic insulated jackets for that matter) check out this article: https://outdoorcrunch.com/jackets/ 

In addition to down, Thorium is also insulated with Coreloft, a synthetic insulator made by Arc'teryx. Just like all synthetic insulators, Coreloft too is much more weather resistant compared to down, and doesn't lose insulating capability under wet conditions. 

If you'd like to read more about Coreloft and other synthetic insulators as well as their working principles, check out the article https://outdoorcrunch.com/clo-values/ in addition to the article I've shared above. 

This brings me to the next point. 

Weather & abrasion resistance

The point of reinforcing a down jacket with synthetic insulators is to provide it at least a little bit of a weather resistance. Because no matter where you live, you don't want to be completely vulnerable to unexpected weather changes. ZERO protection against precipitation is usually unacceptable. 

Reinforcements made in Thorium accomplishes this pretty well. 

We experienced all sorts of snow, rain and drizzle (welcome to Iceland in March) and Thorium did a pretty good job in terms of withstanding it for, say, up to half an hour on average. 

If you need a much more weather resistant jacket with at least the same amount of warmth, then you must forget about down jackets. I'd recommend you to check out Nuclei SV (Men's) and Atom AR (Men's - Women's - read my review) in that case. 

In terms of wind resistance, it's solid and won't cause you any problems, although it's not as solid as wind-proofing focused jackets such as the Nuclei FL (Men's - Women's - read my review). 

Breathability

Thorium is the first of its kind in this regard. 

It's the first light-Arc'teryx-down-jacket that is EVER offered with a two way zipper. 

I've long been mad about Arc'teryx's approach on two way zippers, especially for men's counterparts (almost all of women's parkas offer one but this isn't the case for men's parkas, for example). 

I didn't expect a move like this. Thank you Arc'teryx! 

Now there is a downside to having a two way zipper. It tends to break more often and easily. But I don't see this being a problem unless you're planning to use the jacket for 5+ years. 

It also takes a bit more time to zip it up compared to the ordinary one way zippers. Especially if you have gloves. Two way zippers sometimes do feel annoying to me, but the breathability and comfort advantages also cannot be overlooked. 

I also say comfort in addition to breathability in here because being able to keep the only upper half of the jacket zipper and the lower half unzipped, it's so much more comfortable when sitting down. 

The comfort difference in this regard is much more apparent with the longer jackets (mainly parkas), so don't expect day and night kind of difference with the Thorium in this regard since it's a rather shorter jacket. 

Packability

I'm a big fan of jackets that stuff into themselves. 

One thing to keep in mind in here though is that stuffing and unstuffing a jacket tens of thousands of times can take a toll on its insulating power over time. The ideal way to store a jacket is to hang it. 

Links: 

• https://arcteryx.com/us/en/shop/mens/thorium-hoody
• https://arcteryx.com/us/en/shop/womens/thorium-hoody
• Thorium vs Cerium side by side comparison page on arcteryx.com: https://arcteryx.com/us/en/compare/X000006972-figment/X000006919-black