Crux Plasma Jacket

© UKC Articles
The Plasma: No, it's not a 40 inch television!

It's a snug, 100% weatherproof down jacket that is ideal for keeping you warm and dry in the foulest of weather conditions.

Crux Plasma Jacket  © Crux
Crux Plasma Jacket
© Crux

I've used the Crux Plasma for a couple of months now on cool campsite evenings and early north face starts in the Dolomites, frigid belay stints, bouldering and even on playground duty at school. In short, it's a comforting piece of kit. A bit like cocoa in front of the fire. Or something like that...

The Plasma is a high quality down filled jacket, with a lightweight eVent outer meaning that it is 100% waterproof and very breathable. This is a bonus for UK use where I've always felt down was a little limited, even in winter conditions. I base this primarily on the fact that down is absolutely fantastic in cold and dry climes but we don't really get much of that in Blighty. Even days out in the Cairngorms or on the Ben in January are damp. Cold and icy maybe (if we're lucky), but damp. And down loses it's insulating properties when it's damp (or wet) so that's not good. But with a fully waterproof outer it becomes much more usable.

Cold early morning below Cima Grande West Face  © UKC Articles
Cold early morning below Cima Grande West Face

So, the jacket is waterproof and this has been tested regularly, keeping me fully dry in some foul downpours, including an enormous Dolomite storm. Even the 2 way Riri zipper (a type of waterproof zip which means no storm flap is needed) has performed as well as the hype, allowing no water through whatsoever.

Riri Zippers  © UKC Articles
Riri Zippers

Riri zippers
Riri Aquazips have plastic moulded teeth that mesh and actually form a seal. Even if this seal has only a modest hydrostatic head, it is a significant improvement over the coil zip. Another advantage of the Riri Aquazip is that the slider has no contact with the PU coating support, therefore eliminating any wear and tear through abrasion.
the jacket is waterproof and this has been tested regularly, keeping me fully dry in some foul downpours

The Plasma is also warm and although I've not worn it in full-on winter conditions it has kept me amply well heated during early starts (zero degrees) climbing in the Dollies as well as belaying in a wild and windy Gordale Scar. Perhaps not a full on 'warmest of the warm' jacket, but over your other layers this would be a great belay jacket for Alpine winters and Scottish adventures. It is filled with 160g of 750+ fill weight Polish goose down and it terms of quality it doesn't come much better (see notes on down quality and fill). It is filled in a baffled construction (baffles are horizontal tubes used to compartmentalise the down so it doesn't all flow to the bottom of the jacket) and as the baffles are welded (basically glued) to the outer fabric, weight is saved as are potential leakage points where the garment is stitched. Saying that all of the main seams are sewn, so no flashy laminating of zips or pockets here.

Down: fill power and quality
First of all, down is not all the same. On outdoor products such as sleeping bags and jackets, that is where the 'fill power' rating comes in. However this doesn't tell you much down is present in the garment, but more specifically how much space one ounce of down would fill in cubic inches (or cubic centimetres depending on the brand!) Generally a fill power of 700 and upwards is present in the most specialist products so the Plasma at 750+ is definitely up there in terms of quality.

The cut of the jacket felt generous enough to go over my base layer and 200 weight fleece-backed softshell without feeling restrictive but I wouldn't say it was over-sized as such. Length-wise it drops to roughly hip level and the 2 way zip means it doesn't interfere when belaying. Sleeve length is generous enough so that they don't ride up if you do end up climbing in it! The hem features a drawcord to seal out the elements from below.

The hood

The Plasma has an insulated hood which features a wired visor and drawcord. It is removable via a zipper and velcro and whilst this is a secure system, I can't really think why I would want to take the hood off a jacket of this type. A simple stow system, such as a drawcord or velcro tab, would suffice to stop it flapping around. Also, Crux say that it is ",not sized to fit over a helmet." This I find particularly baffling on a garment that is marketed for Alpine climbing and mountaineering. It does actually go up over my helmet, but not satisfactorily and this is my only real gripe with the whole jacket.

Other features:

The Plasma has elasticated cuffs which I have not had a problem with although I have only had to take it on and off over thin fleece gloves. This may be a different story wearing big gloves in winter. With this in mind, some kind of cuff adjustability would be preferable to aid getting the jacket on and off over gloves and layers. It has two zippered pockets (running up to the chest) which are great for warming your hands as well as securely storing food and other bits and bobs. One feature I am really keen on is the two internal stash pockets. I find these great for warming and drying gloves when my inner gloves get damp as well as stowing belay mitts and other soft items when not in use.

eVent fabrics  © UKC Articles
eVent fabrics

eVent fabrics get their unique properties from a proprietary and patented waterproof membrane. Its unique composition allows millions of tiny pores to breathe at their full potential. Sweat vents directly to the outside of the fabric in one easy step. We call this Direct Venting™ Technology. Its genius is hidden in its simplicity. eVent fabrics simply let the sweat out.™ There is an informative article on eVent fabric here.

In my experience I probably couldn't tell the difference between the breathability of eVent and other membranes such as Gore Pro Shell. Both leave me a little damp inside when I am working hard but nothing too uncomfortable. It's also worth noting that whilst all of these membranes are breathable the tape on the seams is not. That is where welded seams (as used on the Plasma's baffles) where thinner tape can be used, can make a difference to a garment's overall breathability.

great for general cool weather cragging in the UK as well as Alpine and winter use


I really like the Plasma jacket. It is well made, warm and waterproof, as well as being light and well cut. It is great for general cool weather cragging in the UK as well as Alpine and winter use. However as an out and out specialist mountaineering piece I would like to see the addition of a fixed, helmet compatible hood and some velcro adjustability on the cuffs.

Price: £320
Weight: 530 grams

Stockists: UK stockists


Crux Plasma Jacket  © Crux
Crux Plasma Jacket
© Crux

What Crux say:

The only eVent-shelled garment available in the UK, and worldwide the only eVent down jacket using welded seams. eVent fabric is not only waterproof and very breathable, but when you pack it down the air is expelled rapidly through the fabric. Down is best quality available, sourced in Poland. The Riri Aqua zipper uses plastic teeth to form the weatherproof seal – more durable and water resistant than conventional PU-coated coil zips.


  • Full insulated removable mountain hood
  • Roomy chest pockets
  • Lid compartment with central zip, valuables pocket and SOS label.
  • Water resistant Riri zipper
  • Welded baffles give waterproof seamless exterior

Recommended for: Alpine climbing, mountaineering, expeditions

Materials: Lightweight eVent waterproof/breathable fabric outer, with welded seams. Fill: 160g EU 750+ goose down

Colours: Black, Red

Sizes: S-XL

Weight: 530g

For more information the Crux site

9 Oct, 2009
So in terms of a Scottish belay jacket, assuming this stayd dry it should be warmer than any of the synthetics on the market?? What price is it because i can't remember seeing one in the article?
9 Oct, 2009
Found it. Expensive!
9 Oct, 2009
OK I already have one. Yes it is well cut, breathes well and is 100% waterproof. Warmth is a subjective issue but frankly I won't find it warm enough for winter cragging in the UK. It certainly comes nowhere near my old Rab Andes -- yeah I know - overkill. Maybe it compares favourably with other belay jackets on the market but I wish they'd put a few more feathers in it. I bought mine from for £255.
9 Oct, 2009
If it's not waterproof inside as well, would expect it to get wet from your shell, when you slip it over to belay. Hence, probably not all singing, all dancing for Ecose! Stuart
10 Oct, 2009
Hi Stuart That's an interesting point actually. And one that makes perfect sense as the inner is indeed, not waterproof. My feeling with this is that it is not the perfect belay jacket for UK use and for Scotland I would always go synthetic out of choice. Cheers Kevin Avery Gear Editor
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