Synthetic 'down' insulation is bang on trend at the moment. Various new types of fill have come to the market recently, claiming to mimic more closely than ever the loft and warmth-for-weight of bird fluff, but without its wet weather and animal welfare drawbacks. Instead of coming as a sheet on a roll, like conventional synthetic insulation, the new down substitutes are loose, just like down, and that is key to their feel and performance.
Making use of 3M's Polarloft Featherless fill, the Superflux is Mountain Equipment's first foray into this style of insulation, and I think it's something of a success. This jacket is really pleasant to wear thanks to its fluffy loft and high warmth for minimal weight - in fact, if you didn't know better, you'd probably assume that the contents had been donated by a goose.
With a spacious cut that fits well over midlayers, the Superflux is best described as roomy rather than athletic. Its hem sits well below the waist, dropping lower at the rear to provide almost full bum coverage, so protection from the elements is exellent. In my experience a longer body is a hallmark of Mountain Equipment jackets, and testament to thought they put into keeping warm in the mountains. When climbing, this length in the hem helps keep it where you want it, securely in place under your harness; for the rare occasions when I might want to actually climb in a jacket this warm, that's good to know. Under-arm articulation is reasonable - there's no appreciable hem lift - but movement is not quite as unhindered as on some more technically-cut Mountain Equipment jackets such as the Prophet. In overall fit and feel, the Superflux seems rather more of a general-use jacket than a climbing-specific one.
The key question: is Polarloft Featherless noticeably better than more conventional synthetic insulation? Answer: yes, in certain situations I think so. But I wonder if it also imposes certain limits on garment design.
Mountain Equipment tell me they held off on offering down-like synthetic fill until something genuinely decent came along, and the Polarloft Featherless insulation they've developed in collaboration with 3M seems to be just that. This loose fill is blown into the jacket in the same manner as down, and just like down it has to be held in stitched-through baffles. Its loft is impressively down-like, compressing readily, fluffing back up instantly, and offering loads of warmth for its minimal weight (243g of fill in size L for a jacket weight of 535g). To the casual wearer it's pretty hard to tell the difference between this and the real thing; it feels lovely and soft to wear.
Offering a level of insulation that's said to be roughly equivalent to 700 fill power down, it must be among the best performing featherless fills currently available. By way of a synthetic comparison, meanwhile, the Superflux is a similar weight to Mountain Equipment's Primaloft Gold-stuffed Prophet jacket, but if anything feels marginally warmer. The exception to this would be in really minging Scottish winter-like conditions, where the profusion of stitched-through baffles on the Superflux would be a disadvantage.
Being loose fill rather than a sheet, Polarloft Featherless is in theory slightly more breathable than conventional synthetic insulation. This is hard to quantify in use, but my experience to date would seem to bear that out, and I've found the Superflux bearable to wear during moderate exertion (walking gently uphill, say) in moderately chilly autumn weather. On all but the coldest days I'd probably draw the line at actually climbing in it, but in terms of breathability it certainly beats the boil-in-the-bag feel of some of the more conventional synthetic jackets I've used over the years.
The bottom line? In terms of pure warmth-for-weight, the best quality down would still have a considerable edge over this fill. If you're expecting extreme cold, especially dry cold, then stick with feathers. But compared with a mid-quality down of about 700 fill power I've found that Polarloft Featherless does indeed come close. For less extreme cold, and especially in the wet, it has obvious advantages over down. And what's more, you dont feel you have to treat it with the respect you'd give your expensive down duvet. It is more easily washable, for instance. I think this is a useful addition to Mountain Equipment's synthetic insulated lineup, carving something of a niche all its own.
At just 20 denier, the Drilite Loft outer fabric is pretty light stuff, but with a ripstop pattern it seems more than tough enough for general mountain use, and while I might not want to show it the inside of too many granite chimneys I have not yet made a mark on my review sample. It is highly windproof, and shrugs off a passing shower with ease, so mizzly damp autumn conditions have been no problem, and I've only needed to stick a waterproof shell over the top once the rain really starts.
A lack of seams over the shoulders and across the top of the arms increases its weather resistance for winter belays. These are the areas that are going to see the most spindrift, and take the brunt of any rain or drips. However, as I've already mentioned, just like down the loose fill has to be held in numerous small baffles, and thus the stitched-through quilted construction of the rest of the jacket leaves a lot of scope for moisture to get in. This is a key reason why I think the Superflux is only halfway to being a full-on, over-the-top winter belay jacket. When the crap really hits the fan, it's going to be better used as a midlayer under a waterproof. For full foul weather winter climbing duty, then, Mountain Equipment's existing and rather more weatherproof synthetic jackets, such as the Fitzroy and the Prophet, are still preferable.
Though it's definitely more of a generalist than a climbing specialist, the Superflux does still include a couple of techy-oriented features.
Backed with a little anti-snag storm flap, the main zip is a robust YKK Vislon, with a double zipper that allows easy access to your harness for belaying - a feature I've already used several times when cragging. Another nod to climbing use are the hem drawcords, which are two separate strands rather than a loop that you could accidentally clip into when racking gear. Small but important details like this are typical of Mountain Equipment. With no velcro tab for volume control, the wrist cuffs are simple elastic. On the plus side these are comfy and unfiddly; it can however be a bit of a struggle to squeeze them over the bulkiest gauntlets.
The two external hand pockets are huge, easily big enough to swallow ski gloves or an OS map. Positioned quite low on the body, they are partly covered by a harness or a rucksack hipbelt, but a useful amount of pocket remains accessible even then. A single large inside pocket gives you more than enough room for a phone or some cereal bars. One of the hand pockets doubles as a reversible storage pouch which you can clip to a harness; it's not a tiny bundle, but I guess respectably small for a jacket this warm. I'm sure Mountain Equipment didn't intend it, but I've found this doubles, too, as a mini pillow for camping.
Finally, the hood. This is spacious enough to fit over a helmet, but only just; with the zip done up head movement is limited. That's another reason why, although you can use the Superflux as a belay jacket, I'm not sure I would want to in foul weather. Lower face protection is good, keeping the chin covered. But with only a light elastic rim and no side drawcord adjustment, the seal around the face is not completely storm proof, while the lack of any stiffening on the brim means it can flap about in high wind. The single rear volume adjustment is effective at pulling the hood in close and warm around the head though. Overall it's a nice snug hood, and has simplicity in its favour. But ultimately, it feels more like the hood of a midlayer than the sort of helmet-friendly storm haven you'd get with one of Mountain Equipment's more climbing-focused synthetic jackets.
With an impressively soft feel and a down-like springy loft, Polarloft Featherless really does feel like a viable alternative to mid-quality down, and roughly equates in performance terms to 700 fill power down. While its performace can't compare with the best quality down found in premium clothing designed for the lowest temperatures, its advantage in less extreme cold is that it goes on working well when wet. It packs down small, and being synthetic does not need to be treated with the respect you might give a down jacket. In use, this blown insulation feels a little more breathable than some conventional synthetic fills, though I'd stress that this is anecdotal, and I've not yet put it to the test in a full range of conditions year-round.
At £200 the Superflux is not cheap, but that's a ballpark price for quality synthetic insulation, and seems more than reasonable for this brand new, almost-as-good-as-down fill. With its simple cut and less mountain-specific feature set, this jacket is a good all-rounder, but feels less climbing-focused than some of Mountain Equipment's other synthetic offerings, and lacks a few refinements that you might miss in a Cairngorm storm. It is roomy and warm enough to do duty as a winter belay jacket, but while the Drilite Loft outer fabric offers plenty of weather resistance the multiple stitched-through baffles would slightly compromise the performance in foul conditions. If you're expecting the worst then alternatives from Mountain Equipment such as the Fitzroy or the Prophet would still be a better bet. For the full range of winter climbing conditions, the Superflux is perhaps better employed as a very warm midlayer than an over-the-top outer. However for general day to day use, hillwalking or belaying at the crag, the Superflux is all the synthetic insulated jacket you'll need. I'd love to see Polarloft Featherless insulation married to a more climbing-oriented, all-weather design though. Would the quilted construction necessitated by this type of loose fill make that a tall order? Mountain Equipment, the ball's in your court.
Superb all-weather insulation; combining breathability and protection in a single versatile layer.
3M® Polarloft® Featherless insulation not only works wet or dry but, thanks to its blown construction, breathes effortlessly as well. Combined with our highly protective DRILITE® Loft outer and seamless shoulder construction the Superflux is a jacket that thrives as an outer or mid-layer in the most difficult mountain conditions.
For more info see mountain-equipment.co.uk
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