Light insulation layers - moving fast.

I was asked by a club mate the other day about lightweight, insulation layers which wouldn't lose insulative properties when wet. Basically, a good layer for the end of the day on a summer mountain marathon, an emergency warm layer for in the rucksack in the autumn or just something to wear to keep the chill off on an evening socialising outside a chilly pub. (or in fact, an emergency layer for sticking in the bottom of a rusksac when you want to move fast with the least amount of gear).

The answer seems to come in 4 forms, with different offerings from different companies, with broadly the same specifications, slightly different materials and slightly different price points.
As a general guide, you'll be looking at an insulative jacket with the insulation made from synthetic material (yes, down is lighter, but I have yet to come across a down jacket that is truely lightweight and also waterproof so that it keeps the down dry and effective at a competitive price point. When it gets wet, down is pretty useless as a material to keep you warm.

Insulation
Generally, companies are using either a form of Primaloft, or their own version of it. For a few years now, primaloft has been seen as THE synthetic alternative to down. It might not be quite as warm, or as packable as down, but it retains warmth when wet, and packs down pretty damn small. There are a number of versions, primaloft sport, primaloft one, primaloft eco etc, so we might get time to have a quick look at them as we go through the jackets. If Primaloft isn't used then a company will generally use a proprietary fabric - such as Thermic Micro in the case of Mountain Hardwear - of which there really isn't much information about - but more on that a little later.



Montane fireball smock £120
The classic synthetic insulation piece- in my mind anyway. Montane need no introduction as a british brand that have been creating some imaginative solutions to british weather for quite a while. The fireball smock, weighing in at 260g was the first one of this type of jacket I ever saw. It packs down to the size of a largeish apple and has a single napoleon pocket.
The insulation is provided by Primaloft Eco, the most eco friendly of the insulation family. It is made of recycled plastic, and it is claimed that there are 4 plastic bottles in every metre of fabric. (Thats 28 bottles per kilogram, in case you were interested). It is wind resistant and water-repelling.
The fit of the jacket itself is close cut, the shell of the jacket is made of Pertex Quantum, which is a ridiculously light fabric (at 37g per metre), and is apparently a rip-stop polydamide. Which is good news, as to someone who is used to heavier, more robust fabrics, you might be inclined to think its a bit fragile. The inner is made from a soft, quick drying fabric called Peaq, which has the same weight as the pertex.
The arms are relatively long, so if you do get cold hands, you can pull them into the sleeves quite happily and wander around like someone with no hands. However, the cuffs, the neck and the bottom are all elasticated, and so pretty much non-adjustable.

OMM rotor smock £130
OMM have ever been at the forefront of light mountain marathon clothing, and the Rotor smock is a piece of clothing that you may well have seen around at various races. Its 240g - lighter than the Fireball, and looks a bit, well, shiny, with a vivid orange inner. Interestingly, what they have done is use Pertex quantum for both the outer AND the inner fabric, with Primaloft ONE for the insulation, so I suppose you could even say that its reversible. The idea seems to be that the Insulation layer is caught between 2 lots of pertex creating
a pocket of warm, stable air.
As a point of note, the OMM pertex quantum is marketed as being 27g per metre and the Primaloft One as 40g per metre.
The Primaloft ONE differs to the Eco by virtue of not being made with recycled bottles. It is advertised as being the warmest of the Primaloft range, and technically, it has a higher CLO rating than Primaloft Eco - 0.027 when dry as opposed to 0.020, and 0.026 when wet, as opposed to 0.017.
So theoretically, it is warmer when wet, than Eco is when dry.
The Rotor also has a zipped handwarmer pocket, which can accommodate a map, and has drawcord closures at the neck and waist. Like the Fireball, it has elasticated cuffs.

Rab Generator Pull On £110
The most "mountainous" and least " "runner-y" of the insulating smocks - as befits the British Mountaineering specialist, Rab. It is the heaviest on show at 380g, and has 2 different weights of Primaloft in different parts of the jacket - 100gsm on the body and 60 in the arms, making the core a warmer area of the jacket. Like the Rotor Smock, Rab uses Primaloft ONE, and like the Rotor, it uses Pertex Quantum for the inner and outer fabrics.
There is a napoleon pocket, and also 2 massive zipped handwarmer pockets as well. The cuffs are elasticated, and the hem has a drawcord tightener, like the Rotor smock, but slightly different to the Fireball. Perhaps it is the use of the slightly heavier zip and the drawcords that mean this is the heaviest one of the lot.
It is more of a mountain fit than a sports fit - which essentially means that there is a lot more space inside the jacket, so it isn't quite as streamlined as the other jackets. I would suggest that as the heaviest of the jackets, this is probably going to feel like the warmest one of the lot.
Certainly a warm jacket, and not heavy by any stretch of the imagination. Intelligent design with different weights of primaloft in it, and with the bonus of handwarmer pockets.

Mountain Hardwear Compressor Pullover £125
Mountain Hardwear are very popular over in the USA, have an excellent mountain heritage, and have started getting into the whole Trail running thing. (Along with Mammut, Haglofs and the whole gravy train). However, they don't have a massive following in the UK as yet, and seem to be both slightly difficult to get hold of, and also, you don't tend to see many of them around before, during or after races.
As such, I haven't actually seen one of these in the flesh, I've just seen it on a website, it falls into this catagory and looks pretty good.
This is the only jacket here that doesn't use Primaloft, it uses MHW's own Thermic Micro TK, which I can't find much information on. According to MHW it is more compressible and lofts better than "standard polyfill" - or primaloft. The outer fabric is 20D polyester rip (which I'd imagine is ripstop), and there is no information about the inner lining. So its a bit of a mysterious jacket. I'm sure that MHW can give some numbers that "prove" that this is a better jacket than the others, but I just can't see it.
The cuffs are elasticated, and the bottom hem is a drawcord closure, and it features a single napoleon pocket - the jacket weighs in at 235g, so well within the parameters of the others in the mix.
As I say, never seen this jacket, so it might be amazing, and a brilliant fit, but from the fact that you don't see many in this country, I don't stand much chance of that.
I want to believe that it is good, simply because of the pedigree of the jacket, however, the reasons for not using materials like Pertex Quantum, or Primaloft, and using your own versions of the fabrics is to make the product cheaper. Maybe they have done, but those savings don't appear to have been passed on to the consumer. If it used those fabrics, then I could see why it costs this much, but not if they are using their own fabrics.

So I suppose it might come down to this.
Fireball - £120, 260g, Primaloft Eco, Pertex Quantum/Peaq
OMM rotor £130, 240g, Primaloft One, Pertex Quantum +hand warmer pockets
Rab Generator £110, 380g, Primaloft one, Pertex quantum +handwarmer pockets
MHW Compressor £125 235g Thermic Micro, Polyester ripstop

Looking at it like that, I think I'd pay the cash and go for the Rotor smock. 2nd lightest jacket, WITH handwarmer pockets AND the warmest insulation.

The fireball looks good, though is slightly heavier, and with insulation that just isn't as good as that in the OMM. (It seems to be the most Eco-friendly though). It has been said that if you are buying a primaloft jacket with anything other than primaloft One in it, you're being ripped off. Not entirely sure about that, but it has been put out there.
The Rab is great, but in these terms, is just too heavy.
The MHW is the lightest, but the insulation is an unknown, the outer doesn't seem to be as light as the pertex, so the weight saving must appear to come from the fact that the Thermic micro is lighter, and not as insulative. Just speculation, but that's how I see it from this position.

I don't have the cash to go out and test them, but from this little exercise, my money would be spent in the OMM camp.

If Montane or MHW want to change my mind, feel free to drop me a line.



Addentum: Inov8 Race Elite Thermoshell 260 £120
I published this, and browsed for a while, and found that I was already out of date. (who'd a thunk it...)?
Inov8 have just started publicising their new range of snazzy new running clothing, something I was going to comment on in a post in the near future- and I will.
However, more to the point, they have just released the Race Elite 260 Thermoshell.
As you'd expect from the Inov8 naming conventions, it is 260 grams. Again it is a Primaloft filled jacket, but inov8 use Primaloft Sport, which has a Clo rating of 0.023 dry, and 0.021 when wet - slap bang inbetween the One and the Eco.
Like the Rab jacket, it is zoned, using 40g/m weight on the body and 25g/m on the arms- way lower than on the Rab, so most probably less warm. But this is almost exclusively a running piece.
The interesting thing is that this is a truely reversible jacket, using Pertex Quantum on one side, and an airflow layer on the other. So with the Quantum on the outside, it is 10% warmer than the otherway around.
Why would you do that?
If you're out running, and you want a warm layer, but not too warm, then this theoretically gives you 2 weighted heat options in one jacket, enabling better thermal regulation.
Whether or not this actually works is an unknown to me, but according to them, it does.
It also sports a Napoleon pocket, some very nattily designed thumb loops (I've tried them on a couple of other inov8 jackets, and they are some of the better thumb loops around) and packs down pretty small. As you would expect, it is an athletic fit.
Again, I'd love to get my hands on one, £120, again, getting all of these together in the same place at the same time might prove to be a little beyond me.