Winter Baselayers Group Test

What do you look for in a winter baselayer? The fabric should be medium-to-heavy weight, to offer a good amount of insulation for long cold belays, summit stops and winter camps; but at the same time it has got to wick effectively and dry quickly, since getting damp is the last thing you want in winter. A cut that's long in the body is essential, to prevent the hem riding up out of a harness or the waistband of your trousers. A high collar should offer protection to the neck, too, with a deep zip for dumping heat when you're working hard.

What about fabrics? Synthetics have the advantage of stretch, durability and quick drying times; on the other hand they tend to get very whiffy. Natural fibres such as Merino wool may be less smelly, but they are generally slower to dry - and some people hate the feel of wool on bare skin, too. To offer the best of both worlds, wool/synthetic blends have become popular, and several of the base layers in this review have their own take on this principle. Others are purely synthetic. While we have not been able to single out a 'best in test' a number of these tops really stood out for winter use.





Fabric: 100% polyester (220g/m2)

Weight: 284g (size L)

Price: £70

Best in Test Highly Recommended Large

An excellent athletic cut and plenty of length in the body make this a superb winter base layer. The fabric is fairly thick, for warmth, but with a huge front zip there's loads of ventilation too.


Thermal Long Sleeved Zip Neck Baselayer

Fabric: Argentium thermal grid (240g/m2)

Weight: 335g (size L)

Price: £50

Best in Test Good Value Large

With its thick fabric this is a heavyweight base layer best suited to colder conditions. The fit is extremely long in the body - again, a big advantage in winter. Not the most luxurious-feeling, but you get a lot of top for your money.


Trovat Pro Long Sleeved Half Zip

Fabric: Polartec Power Wool

Weight: 195g (size L)

Price: £80

This lightweight top does not offer as much warmth as thicker baselayers, but it's good for all-round use in less extreme conditions. The fabric is an effective and comfy wool/synthetic blend, but the hem could be a bit longer.


Merino+ 160 LS Zip

Fabric: Merino wool / polyester blend (160g/m2)

Weight: 233g (size L)

Price: £70

Its lighter weight doesn't provide the maximum possible insulation, but it's a good compromise for high aerobic output in warmer conditions. The wool/synthetic fabric is quick drying and odour resistant. A bit short in the body though.


Primino 220

Fabric: Merino wool / Primaloft blend (220g/m2)

Weight: 215g (size S)

Price: £85

Best in Test Highly Recommended Large

With its heavier weight combo of Merino and Primaloft, this is the most winter-worthy of the wool blend tops on review, so if you're after a wool option specifically for colder weather use, the Primino 220 is hard to beat.


Satoro AR Zip Neck Shirt LS

Fabric: Merino/Nylon/Elastane blend (180g/m2)

Weight: 222g (size L)

Price: £100

With fabric at the lighter end of this review range, the Satoro does not match the warmth of thicker models. However, as a result it's a good all rounder well suited to high output activities. The wool/synthetic fabric resists odour and it's incredibly stretchy. But the price is very steep.


Ortles Light Fleece

Fabric: Polartec Powerstretch

Weight: 250g (size L)

Price: £110

A cross between super-warm baselayer and lightweight fitted fleece, the Ortles is the warmest top on review, and could easily serve as an outer layer. You'll appreciate it on a long cold winter belay, but less so on the sweaty walk-in. It is let down by its short body and its high price.


Grid Technic

Fabric: Nikwax Parameta G

Weight: 223g (size L)

Price: £55

Best in Test Good Value Large

It's a dowdy-looking design, but the quick drying, wicking Nikwax Parameta G fabric performs really well. It's cool when you're working hard, yet insulates effectively beneath windproof outer layers. But for a couple of niggles this would have been 'highly recommended'

Mountain Equipment

Eclipse Zip Tee

Fabric: Polartec Powerdry (200g and 160g/m2)

Weight: 290g (size L)

Price: £85

Best in Test Highly Recommended Large

In temperate conditions it doubles as a close-fitting mid or outer layer, but as this is a review of winter baselayers that's how we've judged the Eclipse. And on those terms it is hard to fault, with top notch fabric, a brilliant extra-long cut and all the details spot on.



Fabric: 88% polyester 12% spandex (260g/m2)

Weight: 311g (size M)

Price: £28

Best in Test Good Value Large

Basic but effective, the Laika's thick synthetic fabric is warmer than most, but also a little less breathable than the best. It's not great on odour control, but in pure value-for-money terms it's unbeatable.


Neothermo 1/2 Zip

Fabric: Polartec PowerGrid 92% Polyester, 8% Elastane (3.8oz/yd)

Weight: 231g (size M)

Price: £100

Only medium weight by the standards of this review, but the Neothermo is an effective insulator - it's actually billed as a fleece by Marmot. An excellent winter base that doubles as a midlayer in warmer conditions, its cut and performance are superb. We'd have given it 'highly recommended' but for the high price tag.

Jottnar Erling £70

Deep front zip and chest pocket
© Alex Berry

Drytooling - good way to work up a sweat
© Martin McKenna


Though it's not skin tight (at least on us) the Erling is quite close fitting in the body and forearms, which means minimal bulk for layering it under other clothing. It lacks thumbloops - which are not everyone's cup of tea in any case - but with plenty of length in the arms you can climb all day without exposing your wrists. The cut is very long in the body too, so the hem drops well below the waist, particularly at the rear. As a result the hem sits nicely under a harness, or tucks snugly into your trousers with no danger of riding up over the course of the day. In winter conditions in particular, a long body is just what you want. A double thickness of fabric at the neck feels good and snug, and helps the collar stand upright; if the collar had been cut a couple of centimetres higher however, wind protection for the neck would have been better still. On the other hand, when you're working up a sweat, the front zip drops extremely low for maximum venting. To keep out the draught, this zip is backed with a fabric strip. Seams on the shoulders are flatlocked for comfort under a rucksack, and though they aren't elsewhere in the body we've not noticed any chafing. A small zipped chest pocket is the only additional detail; we'd be unlikely to want that on the hill but have used it for door keys when out running.


Luxuriously soft, and a little thicker than some on test, the 100% polyester fabric has loads of stretch and provides a good level of warmth. This certainly feels like a winter weight base layer, though it's not too heavy for bridge-season use. Its close-woven outer face seems effective at keeping out a light breeze, and slides smoothly beneath other layers of clothing; on the inside a more open weave helps with moisture transport, and trapping air for insulation. Though this fabric is not a big brand name we've found it performs very well in use - quick drying, very breathable, and holding its shape well (suggesting that the Erling should be good for many seasons of hard use).

The smell test

With its 100% polyester fabric you'd expect the Erling to whiff a little, and indeed after a few hours it no longer seems as fresh as summer meadows. A couple of days in, and you can unmistakably smell yourself. But thanks to an odour-resistant treatment the honk is not too dreadful, at least by the standards of old school synthetic base layers. However if you do prefer not to carry a bit of an honest hard working smell around with you - and you don't have a problem with wool in direct contact with your skin - then Jottnar's Uller in yak wool looks an alternative worth considering.

Jottnar say:

New for 2017, the Erling is a highly breathable winter-weight synthetic base layer, designed to keep you dry and comfortable during strenuous activity in cool climates. Synthetic fibres give durability and shape-holding properties. Exceptional moisture-wicking ability, a deep-venting chest zip and flatlocked seams further aid temperature regulation, comfort and performance.

  • YKK chest half-zip for venting
  • Chest pocket with YKK zip
  • Flatlock seams
  • Odour resistant treatment
  • Weight: 284g (size L, our measure)
  • Fabric: 100% polyester 220g/m²
  • Sizes: S - XL men's only

For more info see

Berghaus Thermal Long Sleeved Zip Neck Baselayer £50

Berghaus Thermal Long Sleeved Zip Neck Baselayer on a windy climb/hillwalk combo  © Alex Berry
Berghaus Thermal Long Sleeved Zip Neck Baselayer on a windy climb/hillwalk combo
© Alex Berry


Long in the arms, the Thermal Long Sleeved Zip Neck Baselayer is also cut extremely long in the body, coming down well below the waist. In fact this is easily the longest top in the review. While this may not look too fashionable, out on the hill it is really welcome, eliminating the cold spots that you can get with a too-short base layer, and sitting very snugly under a harness. The cut is close-fitting throughout, yet movement is free and easy, with loads of stretch in the fabric. Though it's thick and warm, the collar is cut rather lower than we'd have preferred, leaving a fair bit of neck exposed. In very cold, windy conditions we've tended to back it up with a Buff. For ventilation the zip has a reasonable length, though others come lower for even more air flow. There's no draught excluding strip behind the zip.


Made from Berghaus' own stretchy Argentium fabric, backed with a fleecy inner grid for insulation, the Thermal Long Sleeved Zip Neck Baselayer feels very thick and warm - almost like an ultra-thin micro fleece. Despite its relative thickness, moisture management is good, and with the open weave of the fabric there's plenty of airflow - just what you want in a baselayer. There's no denying this is a beefy number though, so while it may be simply too insulated for high output activities in warmer conditions, if you're expecting some serious zub-zero winter action then this thickie would be a good choice. As a result it is not notably lightweight, coming in at 335g (size L). In terms of next-to-skin comfort the fabric does not have quite such a luxurious soft feel as some others on test, while the seams - and there are a lot - are bulky and prominent enough that you occasionally notice them in use.

The smell test

Argentium fabric incorporates anti-bacterial silver ion 'technology', which is said to help keep smells at bay. In our experience it works well for a single day, but after a couple of days of hard sweating the top is certainly not odour-free. Would a synthetic fabric with no silver whiff worse still? Almost certainly.

Berghaus say:

The men's Thermal LS Zip Neck Baselayer is a lightweight and breathable baselayer providing thermal protection to keep you warm and comfortable during your winter adventures... The Thermal Baselayer uses Argentium silver ion technology, making it anti-bacterial in nature, and providing moisture management and anti-odour protection. The half zip feature offers additional comfort and extra ventilation to help regulate your temperature while you're on the go.

  • Stretch binding at inner collar gives a closer, more comfortable fit
  • Zip neck allows for additional ventilation on the move
  • Lock down zip pull prevents zip from moving when not in use
  • Weight: 335g (size L - our measure)
  • Fabric: Argentium thermal grid fabric (240g/ m sq). UPF 50+. Thermal insulation 0.2-0.3 CLO
  • Sizes: S-XXL men's only

For more info see:

Mammut Trovat Pro Long Sleeved Half Zip £80

Mammut Trovat Pro Baselayer in use at Wharncliffe  © Alan James
Mammut Trovat Pro Baselayer in use at Wharncliffe
© Alan James


This top has a good snug fit all round - tight on the chest but with enough flexibility for free movement, and slightly looser on the arms (unless you have Popeye forearms). The cut is only just long enough - it does stay in a harness but there is little margin and a taller person than 1.80m might require a slightly longer top. There's a nice collar which is just the right height and tightness, with a decent mid-length zip for ventilation. Seams have been thoughtfully placed away from pressure points on shoulders and elbows.


This is the only baselayer in the review made from Polartec® Power Wool™ which is a bi-component fabric combining a merino wool interior and a synthetic fiber exterior. This is said to give comfort and warmth on the inside but allow moisture wicking from the outside layer. In use we found it to be extremely comfortable to wear and certainly better against the skin than many wool tops and, indeed, some old 100% synthetic tops. The fabric is very light and the top weighs only 195g. That is reflected in it not being the warmest 'second fleece' layer that you might be after for more extreme winter activities; but for general year-round use in less freezing weather this thickness is just the job.

The smell test

Polartec® Power Wool™ claims to reduce odour by pulling moisture away from your skin and transferring it to the outside layer where it spreads and evaporates more quickly. It also contains a silver salt which is supposed to inhibit the growth of odour-causing bacteria. Even after several fairly energetic trips the usual 'sweaty smell' was noticeably absent - maybe I hadn't been trying hard enough, but it certainly felt like I had!

Mammut say:

Perfect symbiosis. The Trovat Pro Half Zip Longsleeve is made from Polartec® Power Wool material, making it an ideal first choice for cold days. The wool on the inside keeps you warm and makes it feel comfortable to wear, while the synthetic material wicks moisture reliably to the outside.

  • Extremely comfortable to wear and ideal moisture management due to the combination of wool on the inside and synthetic material on the outside
  • Offset seams reduce friction on the shoulders
  • Extra-long front zip for better ventilation and good fit
  • Weight: 195g (size L - our measure)
  • Fabric: Polartec® Power Wool™
  • Sizes: S-XXL men's only

For more info see:

Rab Merino + 160 LS Zip £70

Wool - keeping sheep comfy up hills since, well, whenever...  © Dan Bailey
Wool - keeping sheep comfy up hills since, well, whenever...
© Dan Bailey


With a slim fit in the arms and body, the Merino + 160 LS Zip layers well under other clothing. There's plenty of length in the arms, so no cold wrists when climbing. However we find the body just a little short, which combined with a rather loose fit to the hem means that it does not stay tucked into trousers or a harness as well as some tops. There's good stretch in the fabric for freedom of movement, and the flatlocked seams won't chafe under rucksack straps. The collar holds its shape well but it is a little on the short side for optimum winter neck protection; it's also a fraction tight (though out tester does have a thick neck). On the plus side the very deep zip offers loads of ventilation, the zip is backed by a draught-excluding fabric strip, and the chunky pull tab is particularly glove-friendly.


We're not sure what '37.5™ technology' is, but what we can say is that Merino+ is a blend of wool and polyester fibres that offers the smell resistance of the former and the quick drying time of the latter. In terms of Rab's range of baselayers it's a midweight top, though one of the lightest on review here. It's not as warm as some of the heavier alternatives we've covered, and while that's a disadvantage in the coldest winter weather the positive flipside to this is that the Merino+ 160 is better suited to high output activities and warmer conditions. In our experience the fabric breathes well and dries quickly. It has plenty of stretch, but being thin it does have a certain 'flimsy' feel. Our wool-phobic reviewer finds it harsh and itchy next to the skin, but we'd bet that most normal people won't notice this.

The smell test

If you don't like doing laundry, or you're out for several days at a stretch, this is one of the less smelly tops on test. On one particular day out we wore it over a synthetic T-shirt. After a few sweaty hard-working hours the synthetic layer was really quite whiffy and fit only for the washing machine, but the Merino+ top remained completely smell free, and went straight back in the wardrobe.

Rab say:

The Merino +™ 160 Long Sleeve Zip Tee is a mid-weight baselayer tee optimised for warmth, temperature regulation and multi-day use, designed using a unique fusion of natural merino and synthetic fibres with 37.5™ technology.

The super fine merino wool offers softness, breathability and odour control, complemented by the durability of the synthetic fibres and the fast dry times. This intimate blend offers unsurpassed next to the skin performance.

Key technical features include a deep venting YKK chest zip for cooling off, a close-fitting collar and flat lock seams to maximise comfort. Merino +™ baselayers are designed in a slim fit to be worn next to skin.

  • Single jersey fabric construction
  • Deep venting YKK® chest zip, chin guard
  • Close fitting stand up collar
  • Flatlock low bulk seams
  • Weight: 233g (size L - our measure)
  • Fabric: Superfine Merino and polyester with 37.5™ Technology
  • Sizes: XS - XXL (men) 8 - 16 (women)

For more info see:

Montane Primino 220 £85


The Montane Primino 220 has a close fit, even on the thinnest of folk like our reviewer. The length of the garment is in the normal to long range, so it's great for tucking into trousers or under harnesses. It has long arms, and plenty of stretchy flexibility. Although it's not quite in the same league as some of the very longest zips in this test, the mid-length front zip provides a decent level of ventilation for those high workload days. A small strip of fabric also keeps the zip from contacting the skin and draughts at bay. There are no pockets, and nothing fancy about the Primino - simplicity is what we tend to look for in a base layer, so that's a plus in our book.


As the name suggests, Montane have used a blend of Merino wool (50%), PrimaLoft (25%) and Polyester (25%) to create the Primino. Montane say the Merino wool draws any moisture away from the body, while the wicking properties of the PrimaLoft yarns transport this moisture across the garment allowing it to dry quicker. This makes it quicker drying than a pure wool base layer, which we tend to find remain damp for longer than synthetics. In test we found the garment to function very well at keeping dry throughout the day. Montane say its 220g/m2 fabric weight is designed for polar or expedition use, but we've actually used the Primino for winter climbing, winter walking and rock climbing closer to home. It's a great "do it all" base layer for colder weather activities in the UK, and could be used as a stand-alone top in temperate conditions too.

The smell test

This base layer has been treated with Polygiene, an odour resistant treatment. It has now been out on four long winter days, and if there is any activity that will be sure to make you sweat and keep you damp, it's winter climbing. Thanks to its treatment, and the high wool content of the fabric, the Primino has stayed almost completely odour free - although the same can't be said about the user.

Montane say:

Blending the remarkable properties of Merino wool and PrimaLoft®, this baselayer is designed for active use in cold conditions. Premium Merino wool draws vapour sweat away from the body whilst high quality PrimaLoft® yarns wick liquid sweat across the outer surface, allowing it to dry quickly. Treated with odour resistant POLYGIENE® so you can wear it more and wash it less.

  • Versatile year round use
  • Odour resistant
  • Wicking and fast drying
  • Comfortable against skin
  • Flat locked seams
  • Weight: 215g (size S - our measure)
  • Fabric: Merino wool blended with PrimaLoft® fibres (220g/m2)
  • Sizes: S - XXL (men) 8-16 (women)

For more info see:

Arc'teryx Satoro AR Zip Neck Shirt LS £100

Breathes well, weighs little and resists odour  © Pegs Bailey
Breathes well, weighs little and resists odour
© Pegs Bailey


The skin-tight fit of the Satoro is great for both layering and wicking performance; but there's so much stretchy give in the fabric that it doesn't feel remotely restrictive. Sleeve length is good for climbing, and deep double-thickness cuffs give a good snug feel at the wrist. Body length is very generous too, with a hem that comes well below the waist. Unfortunately because the fabric is so stretchy and lightweight it does not have much tightness at the hem, so we have occasionally noticed it riding up when climbing. For the same reason the collar is also a bit loose, with a slight tendency to sag. A mid-length zip offers adequate ventilation, and though others are significantly deeper the breathability of the fabric here should help compensate. You also get a tiny zipped chest pocket, just big enough for a credit card.


As one of the lightest base layers on test the Satoro is less insulated for winter use, but would be cooler than many in summer. Arc'teryx have used something called Nucliex yarn here, a complicated-sounding blend where Merino fibres (81%) are wrapped around a nylon filament (12%), then given added stretchy robustness with some elastane (7%). The aim - as with all such blends - is to combine the smell-resistance of wool with the elastic durability of synthetic fibres, and the Satoro is certainly more stretchy than the similar-looking Rab Merino+; it's too soon to say if it's also more durable. If you tend to find wool next to your skin a bit itchy, the Satoro top will do little to convert you to the merits of Merino. Our resident anti-wool reviewer has found it most itchy when really hot and sweaty - out on a run, for instance. That said, in our unscientific and entirely subjective opinion it is one of the less itchy of the wool tops available, and over the course of long hill days we've managed to forget about it for hours at a time. The fabric offers minimal wind resistance. The advantage of its thinness is that it is breathable and comfy in use, and does not hold onto moisture. Nevertheless, being mostly wool it is not quite as quick drying as the best synthetic fabrics. In common with wool tops generally, it does not feel quite as robust as 100% synthetic alternatives either, and despite that elastane content we suspect that over time it may lose its form-fitting shape unless looked after very well.

The smell test

After a long sweaty day the Satoro is not entirely smell free; but all things being relative, it does not pong half as much as your typical synthetic base layer. If you're wearing a top non-stop for a several days, and washing isn't an option, then this one would be a good choice.

Arc'teryx say:

A midweight Merino wool baselayer designed for prolonged backcountry use, Satoro AR Zip Neck leverages the advanced fabric technology of Nucliex™ STR 180 wool. Each Nucliex™ yarn is created by wrapping Merino fibres around a nylon filament to combine the natural comfort, efficiency and odour resistance of wool with the strength and durability of the nylon core. Elastane fibres maintain the next-to-skin fit. The tall collar adds warmth, and a deep V-neck unzips for rapid ventilation.

  • Gusseted underarms and articulated sleeves
  • Laminated chest pocket with laminated zip
  • Tall collar with a deep zip neck provides warmth with rapid ventilation
  • Weight: 222g (size L - our measure)
  • Fabric: Nucliex™ STR - 180 Nylon Core Spun Merino - 81% Merino wool, 12% nylon, 7% elastane - 180g/m²
  • Sizes: S - XXL (men) XS - XL (women)

For more info see:

Alpkit Laika £28

Warmer than most, and superb value  © Toby Archer
Warmer than most, and superb value
© Toby Archer


The Alpkit Laika has a trim fit, but not super tight. Our reviewer found it fine to use as a baselayer next to the skin, but perhaps reflecting Alpkit's suggestion that it can be both a heavy-weight baselayer or a lightweight mid-layer, don't expect the fit to be as clingy as some super-stretchy baselayers are. The Laika is long enough in the body to stop it pulling out when climbing. All the seams are flat locked and comfortable against the skin, and it has functional thumb holes to help keep your hands warmer if you're not wearing gloves. A half zip allows for loads of ventilation too.


No fancy brand names here, Alpkit just says "88% polyester, 12% spandex" and it is picking a non branded material that allows Alpkit to sell you a Laika for the princely sum of 28 quid – a real bargain. The material itself has a snuggly brushed interior and a relatively smooth exterior. That smoothness makes the Laika layer very easily and means it is well suited for rock climbing and bouldering where you don't want to snag. It is also a bit more wind resistant that some of the more open weave fabrics, but of course also a bit less breathable as a result.

The smell test

If there was anything our review had against the Laika it was that it seemed to get a distinct pong quicker than some other base layers. Chucking it in the wash is easy to do, it comes out of the spin cycle almost dry anyway, and the smell has gone. But after a few hours hiking, or an hour on a bike, the smell was returning again. So yes, it might need washing more often than a baselayer four times its price, but effectively that means that for the same money you could have three of them in the wash and one clean to wear. OK, no one would do that - but there's no denying that the Laika is ridiculously good value.

Alpkit say:

Is it a heavier weight baselayer or lightweight midlayer? Don't sweat over the classification, Laika is pretty much two garments in one. A versatile inbetweener Laika will simplify your outdoor wardrobe whilst maximising your comfort during activity. It's smooth outer face mean it will shrug off all kinds of abuse.

  • Moisture wicking
  • Excellent stretch and recovery
  • Durable smooth face
  • Mid-height collar
  • Deep front zip for ventilation
  • Thumb loops
  • Flatlock seams
  • Weight: 311g (size M - our measure)
  • Fabric: 88% polyester, 12% spandex - 260g/m2
  • Sizes: S-XXL (men) 8-14 (women)

For more info see:

Salewa Ortles Light Fleece £110

Salewa Ortles - thick and warm for winter, though not as long as some  © Dan Bailey
Salewa Ortles - thick and warm for winter, though not as long as some
© Dan Bailey


The Ortles is cut quite tight throughout, which is good in a baselayer provided the fabric has sufficient stretch (it does). The arms have a good long cut. Unfortunately we find it very short in the body though, which gives it a tendency to pull up out of a harness when climbing - assuming you could tuck it under at all. Even when just walking, on several occasions when wearing the Ortles we've noticed a cold spot developing around the waist as the hem slowly rides up; an extra few cm would have made all the difference here. The collar is double thickness for extra warmth at the neck, and given the fabric's fleecy thickness this does feel particularly snug. It is cut high to give good neck protection, while the front zip drops good and low for effective venting. A fairly large zipped pocket high on the chest gives you the option to carry a few small bits and bobs, though we would only be likely to use this if wearing the Ortles as a top or mid-layer rather than as a base.


Whether you consider it a mega thick baselayer or a light and close-fitting micro fleece, the Ortles is one of the thickest tops in this review. As such, it is hard to make a direct comparison with some of the others; but as this is a group test of baselayers for winter we're not going to count its thickness against it. With its soft fleecy lining and smooth face fabric the Ortles' Polartec Powerdry Brushed (92% polyester, 8% elastane) makes it a very warm top indeed, and pretty wind resistant too by base layer standards. We've worn it on top of a t-shirt for cragging on chilly days; but likewise it functions as a next-to-skin layer in full winter conditions. We've also doubled it over another base layer for winter climbing, where it's served more like an extra midlayer. If you're winter climbing or mountaineering in proper sub-zero weather its thickness is an advantage; however when working hard or in more temperate conditions it will inevitably feel hotter and sweatier than a more conventional baselayer. As part of an all-weather layering system it is arguably less versatile than thinner tops; it does however fit a winter niche very well. Warmth aside, the fabric is very stretchy, with 8% elastane. With its fleecy inner face it feels luxuriously soft on the skin, and seems as quick drying as many another synthetic micro fleece. After a few days' worth of use, mainly climbing and some hillwalking, there's a little pilling on the outer face of the fabric down on the forearms which have presumably rubbed the most against other layers - nothing serious.

The smell test

The fabric is synthetic, and because of its thickness you may often find yourself sweating a fair bit if using the Ortles as a baselayer. As a result of both these factors, odour management is not the best, and after a day of hard use you definitely know about it. We have smelled worse, however.

Salewa say:

  • Front neck zip
  • Soft inner collar for increased comfort
  • Ergonomically shaped sleeves
  • Chest pocket designed for easy access while climbing or with a backpack
  • Ease of movement through stretch inserts
  • Optimal moisture transport to avoid chill effect
  • Stretch, double-stitched seaming
  • With bluesign® approved fabric
  • Comfortable fit through flat lock seams
  • Weight: 250g (size L - our measure)
  • Fabric: Polartec Powerdry Brushed 176 BS
  • Sizes: S - XXL (men) 40-48EU (women)

For more info see

Paramo Grid Technic £55

It's warm and quick drying  © Dan Bailey
It's warm and quick drying
© Dan Bailey


It's probably fair to say that Paramo are not generally known for streamlined cuts - but the Grid Technic base layer has a good close athletic fit for efficient wicking and easy layering under other clothing without compromising on movement. The arms are quite generous in length, and come with thumb loops to help hold them up when climbing. Length in the body is about middle of the road in terms of this review - another couple of centimetres might have been better, but the hem does come far enough below the waist to generally stay in place when tucked into trousers or under a harness. The collar has a decent height, but if (like our reviewer) you have a thick neck, then it does feel a little close at the throat. The zip is fairly short though, so the Grid Technic is does not offer as much venting as some of the tops on test; in its favour it is backed by an anti-snagging draught excluding strip. Meanwhile the seams feel quite raised, and after long wear we've found they can niggle a little - along the inner arm, for instance, and at the collarbone beneath a rucksack strap.


This is the first time we've used Nikwax's Parameta G, and it has proven itself a great choice of fabric for a base layer. Its distinctive raised pattern of tiny fleecy grid squares on the outer face is said to help disperse moisture across the surface for quick drying. With an open weave between the grid squares the fabric seems very breathable, so if you're wearing the Grid Technic as a stand alone top it feels cool. The theory is that when you then add extra layers on top, the base layer's grid pattern traps air to help keep you warm, thus offering 'two fabrics in one'. Having put it to the test over several autumn and winter days we'd say it works as billed, so although this is one of the lightest tops on test it's still an effective insulating base layer for winter use. It is certainly very quick drying too, and efficiently wicks sweats away when you're working hard. To double check its drying ability I used this base layer as a towel after a cold autumn dip in a burn (as you do), and then put it back on straight away (in the absence of alternatives). After a couple of minutes' wear, the top hardly felt damp to the skin.

The smell test

Hold your nose. After sleeping in the Grid Technic top for one night in a tent, and then spending the following day tramping about a couple of Munros, it smelled positively ripe.

Paramo say:

A versatile two-in-one baselayer which can keep you warm, or keep you cool. Equally suitable for high mountain use as for cycling or trekking. The Grid Technic uses Parameta® G fabric which provides both insulation and wicking properties. The design includes a zipped neck, thumb loops and an athletic cut.

  • Zip neck for variable ventilation with zip garage for comfort.
  • High collar for protection from sun or wind.
  • Long sleeves which can be easily rolled or pushed up.
  • Thumb loops to hold sleeves in place when required, reducing any gap between glove and jacket in order to maintain hand warmth.
  • Generous length to protect the lower back during all activities.
  • Contoured shape and athletic fit minimise excess fabric, reducing flap on the move.
  • Weight: 223g (size L - our measure)
  • Fabric: Nikwax Parameta G
  • Sizes: S - XXL (men) XS - XL (women)

For more info see

Mountain Equipment Eclipse Zip Tee £85

So well vented it's positively indecent  © Dan Bailey
So well vented it's positively indecent
© Dan Bailey
Zips up good and high for max snugness  © Dan Bailey
Zips up good and high for max snugness
© Dan Bailey


For us, the fit is absolutely spot on for a winter base layer. Close fitting yet cut for full freedom of movement, the Eclipse layers well under other clothing. Super-long in the body, with a hem that sits comfortably well below the waist, it stays firmly in place when tucked under trousers or a harness, and never seems to ride up when you're climbing. No cold spots around the waist, and almost complete bum coverage - what's not to like? The arms are cut long enough for climbing, and for extra coverage you get the option of thumb loops; the cuffs don't readily roll up over the forearms, which in summer weather is really the only disadvantage of the Eclipse's cut. The neck is brilliant, coming a little higher than most on test and standing up well to offer maximum warmth and protection. At the same time the front zip drops really low, right down to the base of the sternum, to give a massive amount of ventilation. When you're working hard and feeling a little too layered up, instead of faffing with clothes you can simply unzip all the way and bare your nipples to the world. Full beam ahead! Mountain Equipment have provided a spacious mesh-lined zip pocket on the chest, which is probably overkill for a baselayer but makes more sense if you're using the Eclipse Zip Tee as a stand-alone or mid layer.


Thicker and warmer than most in this review, this luxurious-feeling top is listed on Mountain Equipment's website under 'fleece clothing', but it's a hard one to categorise. The Eclipse can equally function as a light mid (or ever top) layer in spring and autumn, or as an extra-snug winter baselayer - and that's certainly how we've been using it. Made from two different weights of Polartec Power Dry, the fabric has a close-woven outer that slides smoothly beneath other clothing, while on the inside it's a fleecy micro-grid pattern that helps trap air for warmth without weight or bulk. It's basically a mirror image of Paramo's grid-out fabric, and in use it seems to function equally well. For its modest weight - less than 300g (size L) this top is really quite warm. The fabric is very stretchy yet feels robust; it wicks sweat away from the skin very effectively, and it's quick to dry. The fleece inner is comfy next to bare skin, and the flatlock seams don't irritate at all. It is perhaps a bit thick and warm for hotter conditions, but as this is a review of winter base layers we're not going to quibble.

The smell test

With a Polygiene treatment, this is notably less smelly than your average synthetic base. After wearing it for one night's camping and then on a fairly hard working scrambling day, for instance, there was undeniably a bit of a whiff - but not half as offensive as we had been expecting.

Mountain Equipment say:

A close fitting zip tee for any fast moving mountain sport that requires maximum insulation and stretch. A year-round piece for the most demanding applications, the Eclipse Zip Tee can be used as a heavyweight base or lightweight mid-layer. Wear it alone for rock climbing or as part of warmer layering system in the mountains; it is fast drying and completely unrestrictive.

  • Polygiene® anti-microbial technology; environmentally friendly and Bluesign® approved permanent odour control
  • Active fit
  • Flatlocked seams throughout for next-to-skin comfort
  • YKK® deep centre front zip for ventilation
  • Napoleon chest pocket with mesh back
  • Seam-free hips for comfort with a harness or rucksack
  • Weight: 290g (size L - our measure)
  • Fabric: Polartec Power Dry 200 fleece for warmth and minimal bulk; Power Dry 160 fleece panels in key areas
  • Sizes: S - XXL (men) 8 - 16 (women)

For more info see

Marmot Neothermo 1/2 Zip £100

There's a lot of insulation here, but you pay a lot for it too  © Toby Archer
There's a lot of insulation here, but you pay a lot for it too
© Toby Archer


The Neothermo has an excellent athletic fit. For our reviewer the medium was near perfect: snug but never tight and long arms meaning that even reaching up when using the thumb loops there was no pulling. The body is long – our reviewer could pull it down over his bum, absolutely no chance of it pulling out of climbing harness, making him suspect it would be a good choice for taller types as well. The half zip means lots of ventilation is possible, but in the cold it zips up to just under the chin for maximum neck coverage. The zip has a baffle behind making it very comfortable, even to sleep in. There is also a small zip chest pocket for keys or similar.


The Neothermo is made from Polartec® Power Grid, a lovely soft 'waffle' material. The grid pattern on the inside of Power Grid means excellent breathability plus increased insulation for lower weight. The weave on Power Grid is quite open so don't expect much wind resistance from it but this is a baselayer where wicking and breathability is the prime consideration – something the Neothermo is excellent at. Interestingly the more open weave doesn't seem to make it any less tough; on the first day out the reviewer accidentally ended up arm barring up a classic Rivelin HVS wide crack. The Neothermo emerged at the top unscathed, our reviewer slightly less so. Overall we've found the Neothermo makes a great winter weight baselayer or a great light micro-fleece over a snug, thin, light baselayer.

The smell test

Surprisingly good – yes, wear it all day including long sweaty walk-ins and the like and by evening there will be a bit of a whiff, but in the scheme of these things it's not too bad. Our reviewer wore the Neothermo constantly for a 24 hour trip that included a chilly overnight camp (where it worked well as a pyjama top) without stinking out the car on the drive home.

Marmot say:

The Polartec® Power Grid of the athletic fitting Neothermo ½ Zip is the perfect moisture-wicking layer that allows you to still get out in cold, cantankerous conditions and build a solid base.

  • Athletic fit
  • Flat Lock Construction
  • Zippered Chest Pocket
  • Elastic Bound Cuffs with Integrated Thumb Holes
  • Weight: 231g (size M - our measure)
  • Fabric: Polartec PowerGrid 92% Polyester, 8% Elastane Stretch 3.8 oz/yd
  • Sizes: S-XL (men) XS-XL (women)

For more info see:

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13 Feb, 2017
It's a shame that more budget brands aren't included. It would be interesting to see whether the big brands are worth the hefty price tag.
13 Feb, 2017
I have been using these tops for some time now and really cannot fault their performance:
13 Feb, 2017
I used the Alpkit Laika for the Spine Challenger layered over a Brynje Super Thermo "string vest" (shame you didn't review one of them too!). Worked well, although I agree I noticed it ponged a bit too!
13 Feb, 2017
Were none of the testers brave enough to try the Brynje mesh tops?
13 Feb, 2017
Also a fan. I have hooded and non-hood, both are great. I've compared the non-hood one with my Marmot thermo 1/2 zip (~£100rrp but I got it for £30) and there's very little difference in performance.
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