Saturday, 17 December 2011

Rab Powerstretch Review

Base layers are the fulcrum of our clothing selection yet so little is written about them in comparison, for example, to shell layers and insulation layers. This is strange, in reality, as the base layer is far more important than any other layer. Get the base layer right and you have a stable base from which to build a clothing system. Remember what clothing is about - regulating body temperature and hydration, whilst remaining comfortable. There really is, modesty aside, no other point to clothing. So if you cannot get sweat away from your body whilst maintaining core, and surface, body temperature, you'll get cold (and uncomfortable). Base layers are designed to do that, if you make your selection carefully. Yet the process of evaporation - for that is what 'wicking' is, or at least moving towards - is thermodynamically designed to reduce body heat in summer and to maintain it in winter. Wet clothing, which does not evaporate the moisture contained within it, sticks to our skin and, through the processes of conduction (ambient cold air touching the fabric) and convection (cold air being forced onto the fabric by wind, for example), the fabric cools down, as does the moisture and we become cold. If that moisture evaporates, we are kept warm.

Different base layers work most efficiently in different activities and temperatures. Also, I firmly believe that the fewer layers you have on, the easier the process of evaporation is going to be. In winter, I have a maximum of two layers when moving and the top layer is usually Páramo. Sometimes I may only have one layer - Buffalo. My winter base layer thus far as been the classic Patagonia R1 Regulator Hoody and I have not been disappointed.

So, when Go Outdoors asked me to test some kit for them, I selected a rucksack and the 300g Rab Powerstretch or, to those 'in the know' the "PS Zip". I'm all for being hip and down with the kids, so I'll call it that. This latter was intended to compete with the R1 Hoody for situations when I did not want a hood - more specifically, alpine.

Powerstretch® fabric is a 4 way stretch, high wicking fabric designed for active sports. The PS Zip Top is a close fitting, quick drying, wind and abrasion resistant pull-on designed for active users. The PS Zip Top is an ideal mid layer or can be used as a base layer next to the skin in cooler conditions. This from the Rab website.

Polartec® Powerstretch® fabrics feature body-hugging 4-way stretch and are very breathable. They keep you dry when you sweat and provide warmth without weight. These are the most versatile outdoor and fitness clothing fabrics available today. Many of the fabrics feature a proprietary construction with two unique surfaces: the durable, smooth outer layer is wind and abrasion resistant; the soft inner layer pulls moisture away from your skin keeping you dry, warm and comfortable. This from Polartec's website.

So, it's a 4-way stretch, figure-hugging piece. This is true. I ordered a medium and it is very tight and perhaps just as a touch too small. Thus, if you would normally be a medium in most things, you might want to consider ordering a medium and a large and seeing which is better.

The outer layer is a nothing new - Polartec's proprietary wind and abrasion resistant material that feels smooth to the touch. The inner is rather like micro fibre fleece. It feels pleasant enough against the skin. 

It's a base layer. So, really, features on show are minimal but it's the smaller, not seen bits that make it special. The flat seams are smooth against the skin to ensure no chaffing and redness after scrambling or climbing (or an other high-octane activity). I like thumb loops when I am wearing gloves - it means my sleeves do not ride up and expose my wrists. I like a complete, compact, secure unit around my hands and arms - I don't, on an exposed grade 3 scramble, want to be worried about getting cold because by wrists/forearms are exposed.

The deep half zip is great for swift venting. Unzip and the perspiration virtually steams from your chest in cold weather, after activity. The tight fit is a good one, in reality. No loose clothing is exactly what you want in the activities this base layer is designed for. The collar is a good one - high enough to cover your neck, angled in a concave fashion to permit additional neck insulation layering (i.e. a scarf) and the zip has a small, fleecy housing for comfort. There is the ubiquitous napoleon pocket which I am boring myself to make use of in some way as my Cypher has one, the Rab V-R has one and the R1 has one. So outdoorsmen everywhere must love them and I cannot be a professional outdoorsman without making use of it, it seems to me. So I put stuff in there to look like I know what I am doing. Good stuff, useful stuff. Honest. Usually, a compass. Bear in mind that anything you put in there will get very damp indeed.

The Review
I took this into North Wales with me for two days when I did a recent Grade 2 and 3 scrambling weekend with our alpine guide and friend, Nigel Shepherd. The weather, and temperatures, was somewhat bipolar - rain, wind, sun, cold and mild. The whole gamut. Each day, I was in the PS Zip for around 7 hours and, after day one, I left it to dry in my room for use the next day. So, sure, this is a very short-term test. Take from that what you will. Some may say little can be discerned from such a short test. I agree, but you may still benefit from my observations.

It kept me warm. I felt comfortable. My skin was not particularly clammy although I certainly could not say I was dry after hours of wind, rain and hard (terrifying) work. But no base layer would achieve that. The range of movement was great. In fact, the best thing I can say about it was I did not notice I had it on. It dried overnight. It felt fine the next morning when I put it on. It did not smell much. I think after a second day it would have been pretty odorous to wear another day.

My layering system was PS Zip, Rab Vapour-Rise Smock and OMM Cypher. I only put the Cypher on when the rain came. Wind was kept at bay pretty well but I genuinely query how good the V-R is at keeping 50mph+ at bay - a shell is far better for that.

So what do I think? It fits a niche in my wardrobe. It is as good as any winter base layer I have used (thus comparing it to 200g merino, R1 Hoody and Páramo Mountain Pull On). I like it and I will use it. I did not, for example, like the Páramo Mountain Pull On - so I ditched it. This is far superior and I look forward to some Scottish winter mountaineering in it.

My thanks to Go Outdoors for the PS Zip and the following links may assist in finding the PS Zip and other thermal layers art reasonable prices.

Base Layers
Rab Products


  1. Bah, needs a hood!

    Utterly love my PS Zip. Still going strong after 3 Norwegian winters. Comfortable beyond belief, simple, dries quick (but maybe not as quick as Power Dry). Stick a hood on it Rab!

  2. Mountain Equipment have one - the Couloir I think it is - which has a hood. In fact, because of the R1, I wanted one without a hood. But what a good base layer!

  3. Yeah, the Couloir is like some of the other Power Stretch hoodies out there, in that it has a full zip so is kind of aimed at being a midlayer rather than a base like the PS Zip. I have a much loved but also much battered Shroud hoody for my fleecey hooded mid layer requirements at the moment.

    I like that there is still a place for quality fleece garments in our arsenal. 

  4. Thanks for the review Maz. It looks a warm garment for me. What do you think about a Silkbody 1st layer and then the PS zip as a mid layer under the Cypher.
    BTW i think those small pockets as on the Cypher and others are pretty useless. If it hadn't been for that poor Cypher pocket i wouldn't have lost my Suunto watch. The Cypher (apart from the pocket and cuffs) is great.
    I do prefer base layers that don't need washing every other day though.

  5. Alan, I think that another layer under the PS Zip is certainly possible but I am not sure I would personally want to do that. It could be used as a mid-layer but that would mean a larger size which would accommodate another layer underneath and leads to a slightly baggier fit as a base layer. It depends on your needs I guess and it is what I do with the R1 but I find it a little big as a base layer alone. If you don't want a base layer which requires washing it has to be merino as you know but they don't dry as quickly when thick enough to compare to the PS Zip.

  6. Maz,
    Having now had a proper look at it i think it’s a nice bit of gear and one i will probably get when i come back from NZ. The lack of hood doesn’t bother me because i wear a thin balaclava as a buff/hood and considering how much the ME hoody costs then this is a bargain at £40 here. 
    Its also cheaper than Gooutdoors. Ooops. (But not as cheap as free).

  7. Good review Maz with some first rate photos. I have ordered some Rab PS trousers for winter. Not sure I would like a hood on this type of clothing. I like to wear a separate PS balaclava.
    BTW some good photos on

  8. Thanks Mark. Glad you like my freelance site.

  9. I love my PS zip, just the right weight for winter under Paramo, whilst moving anyway...

  10. Precisely my thoughts - Páramo Aspira and PS Zip

  11. I adore mine. Used it for many a trip.  Thread here and there coming lose.  But wearing well.  Zip pocket is always not needed IMO.  I did not take it on the TGO and missed it.  A good review of what is a good bit of kit.  

  12. I've got one to wear as a midlayer.  I've had to size up to do this, as you said, but I knew that already (and wish Rab stuff was available in a size '9').

    I took it away to Nepal with me and wore it as a jumper every evening for just under three weeks (base layer + PS Zip + Photon).  It was warm and comfy, which is all I need really.  I didn't use the pocket.  Napoleon pockets aren't great on girls.  Though I do keep my glasses in the one on my Vapour Rise.

    I haven't tried it as a base layer, and having caught something horrid and lost half a stone, it'll be too big for that for a while...