A new Phase in base layers from Arc’teryx…
Rating (out of 5)
Performance: *****
Quality: *****
Value For Money: *****
Price: £45.00

The Phase range of base layers, from Canadian uber-brand Arc’teryx, sounds nothing new on the face of it. You wear it next to the skin and it breathes, transporting moisture away from the surface of your skin during sweaty pursuits like running, climbing and ski touring. When you stop for a break, or to belay your mate, you don’t cool down as rapidly because the sweat has been transported away from your skin. Most base layers do this to a degree, but some are definitely better than others.
The Phase AR Zip Neck is a lightly insulated (I’d call it midweight, heavyweight being stuff like Powerstretch and Patagonia’s R1 garments), long sleeve, base layer top with a half length zip for easy venting. Arc’teryx claim it is engineered, “for optimal moisture management during stop-and-go activities.”

So how does the Phase fabric work?
Arc’teryx claim:
“During active phases moisture is wicked across the entire garment, aiding temperature regulation. Entering a rest phase the broadly dispersed moisture evaporates quickly, speeding dry-time to keep the user warmer and more comfortable.”
So, back specifically, to the AR top.
I have worn it next to my skin all winter for everything from long runs in the Yorkshire Dales, ice and mixed routes in Scotland and the Lakes, ski touring in the Alps, razzing down Scottish pistes and bouldering on the local grit.
Video: The Phase on test in Les Houches, France
In short, it is a fantastic top, superbly cut (not quite “tailor bespoke” but pretty close); the fabric stretches with the body, is comfortable next to the skin and the quality of workmanship is high.
I particularly liked the extra length in the body, which means it doesn’t ride up when I’ve tucked it in to my bottom layer. The sleeves are also amply long enough so that they don’t ride up when you’ve got your hands above your head. Ease of movement when wearing the Phase top, is also enhanced by the anatomical shaping of the garment (it’s designed with the shape of your body in mind!) and the inclusion of underarm gussets.

Other features to bear in mind when thinking about comfort are the stretchy characteristics of the Phase fabric (which stretches without the addition of any Spandex or similar fibres) as well as the flat seams, laminated chin guard and bonded, non-chafing label. All of these elements help to create a garment that is comfortable to wear all day, every day. No chafing, no itching, no restriction and surprisingly, no stench!
On the subject of odor, the Phase appears to retain minimal amounts, well as far as my sense of smell can tell anyway! The fabric incorporates encapsulated silver ions which are supposed to provide durable odor control. And it appears to work! I have worn this top for 8 straight days and whilst in other base layers I would barely have been able to share a room with myself, in the Phase the odor levels were pretty minimal.
However, whilst all these things are important in a base layer, the main question is always going to be, does it breathe and wick moisture away from your body?
Like I said earlier I have used the Phase AR top for a variety of pursuits ranging from sedate to highly aerobic, with a lot of stop-start in between. Worn next to the skin I have found that moisture transportation during aerobic activities, has been generally awesome. I still get a damp back when lugging my climbing pack up to the Ben or wherever it is I am going, but this soon dries out when I stop (quicker than most other base layers I have used) and I would be more than interested in testing any base layer that gets rid of this problem. During constant exertions such as running breathability is excellent and the Phase dries quickly once I’ve stopped.

The half zip gives extra venting and allows you to tailor the breathability depending upon chosen activities and weather conditions. I’d like to see a more glove-friendly zipper tab as standard with winter in mind though.
Because the Phase AR is a mid weight it is also excellent for less aerobic activities such as rock climbing. It feels much warmer than it’s weight suggests and it is also very wind resistant (although not 100% windproof). This top is ideal as a cold weather base layer but will be too warm (for most) as a base layer during the summer months. Perhaps try the Phase SL Crew instead.
It will however, be perfect as a light insulating layer for those cooler summer’s days and I’ll definitely be giving mine a few outings on the UK mountain crags as well as in the Alps and Dolomites this summer. The half zip that I mentioned earlier will help with ventilation, particularly in the summer months, so this feature adds to the garment’s versatility.
In Conclusion
The Phase AR is an excellent mid weight base layer, constructed from a superbly durable and breathable stretch fabric. I particularly like the cut, length and moisture transportation as well as the fact I don’t smell like a skunk after multiple days of use.
Use the Phase AR Zip as a base layer for all your winter pursuits. However it would be nice to see a glove friendly zipper tab.
- For more information about Arc’teryx base layers, visit the Arc’teryx website
- For UK stockist info contact Big Stone
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