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August 21, 2019 11 min read

In this blog we hope to create the ultimate guide to Women's Base Layers. If you are heading outdoors, whatever your adventure whether that's skiing, snowboarding, ski touring, split boarding, hiking, mountain biking, trail running or climbing making sure you have the right first layer* is really important. 

Why bother? Most of these activities involve working up a sweat, you are outdoors and exposed to the elements and having the right kit means that you can not only perform to the best of your abilities but also stay out as long as you want to. So ending up in hospital would be pretty bad, but we're also not a fan of returning back to base because we are too hot, cold, sweaty or even worse your kit has rubbed in places you really don't want it too!

We've taken a detailed look at the types of fabric base layers are made of including Merino Wool base layers, Polyester, Spandex, Cotton and Bamboo.

Today, there are literally thousands of base layers on the market, gone are they days of wearing old fashioned ladies thermal underwear to keep you warm! Today's fabrics are lightweight, warm or cool and with a focus on design that takes you from Mountain top to street without even having to change. We have also reviewed this season's most stylish Ski Base Layers too.

* other words for first layer include base layer, thermal, thermal underwear, skins, tights and pretty much any combination of the above! 

Here's what we'll cover

Choice of fabric 

Depending on your point of view this is arguably the most important part of choosing base layer. The material or fabric that the garment is made from will determine many of its performance features such as whether it is sweat wicking, lightweight, how stretchy it is and whether the fibres are natural or man made. Different fabrics also have different carbon footprints and impact on the environment.

First we'll discuss the different properties of the fabric and then we'll talk about the different kinds of fabric used in making women's thermal base layers.


Womens base layer infographic

Sweat Wicking: Most outdoor activities or sports will cause you to sweat as your body generates heat as you use your muscles to exercise. Sweating is important as it helps you to regulate your body temperature; but if that sweat (which is essentially salty water) sticks around on your clothes then it can make those clothes heavy and wet and could cause you to get cold quickly once you stop exercising.

This is particularly important if you are exposed to colder temperatures (such as when skiing or snowboarding) where your body temperature could drop very rapidly. Some fabrics "wick" or pull the sweat away from the body, the fibres are designed with a large surface area which picks up water and allows it to move to the outside of the fabric where it can quickly evaporate. These fabrics are also quick drying meaning that you won't be feeling cold and wet as you stop exercising, cool down or are exposed to the elements. 

Examples of sweat wicking base layers include Merino Wool base layers and Polyester base layers.

Cotton base layers are not particularly sweat wicking or quick drying making them a poor option for outdoor sports. Cotton fibres just love to hold on to water!

Stretch: We LOVE a bit of stretch in our fabric, not only does it make it super comfortable but also aids performance letting us stretch, bend or reach as far as our bodies will allow. As long as it isn't too clingy - we're looking for just the right balance of course!

The stretch in the fabric refers to its ability to stretch without breaking the fibres of the fabric, returning to its original length, some fabrics are more elastic than others.

Lycra®, Elastane, Spandex - what's the difference? Essentially they are all the same thing! Elastane for fabric use was invented in the 1950's, the American's liked to call it Spandex, and Lycra® was the original brand with a registered trademark. 

You generally won't find a garment made entirely out of Elastane, but it is blended with other fabrics such as Polyester or Merino Wool to make base layers with stretch properties. Generally using 5-20% Elastane would give the fabric stretch properties. 

Lastly Elastane is a man made polyurethane fibre, if it is added to a natural fibre such as Merino Wool these fibres can't be separated and so whilst the Merino Wool can biodegrade, the Elastane can't. If you are searching for an environmentally friendly base layer you may want to check whether the garment also contains some man made fibres. Some recycled Elastane is now available but with little existing infrastructure for recycling Elastane, there is a long way to go before reaching a truly circular economy here.

Lightweight: The best examples of lightweight base layers are usually made from Polyester or Merino Wool. Brands will also make women's base layers of different weighted fabric, this is measured in "GSM" or grams per metre squared, the higher the number, the thicker or heavier the fabric will be. 

Some brands will classify their base layers as "lightweight" "midweight" or "heavyweight" Odlo and Icebreaker both use similar classification systems to help you pick the right product. We'd suggest if you are being very active, and its warm picking a lightweight base layer and if you are doing a slower paced activity in cold weather picking a heavyweight base layer or warm base layer.

Natural Fibres: 

  • Merino Wool - Merino wool is a natural fibre produced by Merino sheep and is great for making clothes because it is finer and softer than regular wool. This also makes it the perfect fabric to wear next to the skin, as a base layer. We've written a whole blog post on Women's Merino Wool base layers, so if you are keen to learn more check it out.
  • Cotton - This is grown from the Cotton plant and made into a textile fibre. Cotton is a natural fibre but can use a lot of synthetic fertilisers and pesticides in the growing process, so if avoiding these is important to you then you might want to look for Organic Cotton products. As discussed above Cotton wouldn't be our first choice of base layer but a great fabric for making into a t-shirt for throwing on after sport.
  • Bamboo - Bamboo fibres are made from extracting the cellulose from the Bamboo plant. Although its a natural fibre, it takes a lot of processing to make the final bamboo fabric and some of these processes can be harmful to both the environment and workers if a closed loop process, or care is not taken; so it is important to consider who is manufacturing your bamboo clothing. For similar reasons to Cotton Bamboo wouldn't be our first choice of base layer.

Eco-Friendly: We have ticked Merino Wool, Bamboo and Polyester as being eco-friendly in our infographic, however each of the above comes with caveats! As described in the last paragraph, whilst Bamboo is a natural fibre and will bio-degrade some of the manufacturing processes to arrive at the finished product can be extremely harmful to the environment, so choose your supplier carefully! 

Merino Wool will also bio-degrade naturally however again we'd suggest you check your brand carefully and ensure that they are using Merino Wool from muelsing free sources (Muelsing is the process of removing strips of wool bearing skin from the Sheep). For example Mons Royale (shown below).

Mons Royale Merino Wool Base Layer

Perhaps surprisingly we have included Polyester as an eco-friendly fabric, you could probably argue both sides here but if you are going to buy a polyester base layer and you want to reduce your impact on the environment we suggest you go for a recycled polyester option. Brands are increasingly using recycled polyester rather than virgin polyester in their supply chains and consumers have the opportunity to demand a faster rate of change here. Recycled polyester fabric can easily be obtained from companies such as Repreve who repurpose recycled plastic bottles into polyester fibres using less water and energy than creating virgin polyester fibres.

Repreve recycled base layer tops

Wrapping up our section on base layer fabrics, there is certainly a lot of choice! We'd suggest a Polyester or Merino Wool base layer for the ultimate performance, and the addition of some Spandex or Elastane will give it a little more stretch. If you have any questions please let us know at hi@thelatitude.life and we'll do our best to help!

Design features in Women's Base Layers

There are some great, simple base layer's on the market such as the women's long sleeved base layer from Mons Royale below. However, Mons Royale have really paid attention to the detail in this simple top with some design features we will explain below including flat-lock seams, thumb loops and a dropped tail.

We've also written a blog post on the season's most stylish Women's base layers too.

What are flat-lock seams?

Sections of fabric are usually joined together by overlapping and sewing two pieces of fabric together, however this creates extra fabric within the garment which can then rub as you move your body during exercise. Flat-lock seams create a flat join between two pieces of fabric by lying the two sections side by side and sewing the two raw edges together, leaving no spare fabric and making sport MUCH more comfortable! 

 Mons Royale Long Sleeved Merino Base Layer

Mons Royale Bella Tech Merino Base Layer 

What are thumb loops?

The Marmite of ladies base layers! Love them or hate them? Let us know! Thumb loops are the addition of a thumb hole to a slightly longer length sleeve keeping your hands warmer if you are out in the cold. They can also help stop the sleeve riding up underneath another layer. Personally? We love them! As long as you find a brand that has paid attention to the size of the loop, a big loop or bulky fabric can make it quite uncomfortable. So choose your brand carefully (Mons Royale are a great choice here) and if you get tired of the loop just double back the sleeve!

What is a dropped tail?

If you are looking for a long base layer then consider one with a dropped tail, with slightly more fabric at the rear the base layer extends towards your bottom. This is a great design feature if you are skiing or snowboarding and want to tuck your top in to ensure you don't get snow down your ski pants when you take a fall! And we like it as a design feature too, giving the product a more relaxed look.

Hooded base layer

If you are looking for a hooded base layer then look no further than Eivy! Their original Icecold hooded base layer top is a great option. Eivy have designed their tops with skiers and snowboarders in mind and so the hoods fit sleekly under a helmet making them the ideal option if you don't want to wear a snowboard or ski balaclava. Some hooded tops can be a little bulky so this feature is worth considering carefully if you want to wear the hood under a helmet or down, and under a women's ski or snowboard jacket. Check out the Eivy Women's Ice Cold Leopard Print Base Layer Hooded Top below.


How to wear your base layer - the art of layering!

To maintain a constant body temperature, not too hot and not too cold a layering system is critical. Layers can be added or shed as needs be also trapping air in between the layers to help regulate temperature. This is such an important topic we are in the process of creating a guide just for layering. But we'll provide a shorter version here! 

  • First Layer - this is your ladies thermal, base layer or underwear. Whatever you call it, next to your ski you will want it to be comfortable, sweat wicking and the right weight of fabric to keep you warm or cool as needed
  • Second Layer - this is your women's mid-layer, insulator or fleece. This is usually the layer that adds some warmth and so will be made of a warm and fleecy fabric, typically Polyester, Merino Wool and may contain some down or insulating material.
  • Outerwear - there are a huge range of outerwear options on the market, the outer layer is usually waterproof (although this can vary significantly from jacket to jacket) and potentially also contain some insulation. There are many different types of Outerwear from insulated two layer jackets to three layer (3L) jackets (also sometimes called "shell jackets") or rain jackets. Again, we will cover this in another guide as its a hugely important decision to make. With an insulated two layer jacket you may well not need a mid-layer however this will depend on how much insulation the jacket contains, and of course the weather!

Types of Base Layer

Women's Base Layer Tops

We have covered a few of the key features above, if you are looking for a women's ski base layer top then we we'd definitely suggest going with a long sleeved option and consider a heavier weight fabric if you are skiing in mid-Winter or colder days. We stock a great range of long sleeved tops from Eivy, Nikita and Mons Royale.

Another feature to consider is a zipped top. Floa, a new British brand who have brought a highly technical offering to market (including a backcountry collection) are worth checking out. Their Merino half zip baselayer is shown below.

Floa all action merino half zip baselayer

Floa All Action Half Zip Merino Base Layer

If you are looking for a short sleeved vest top for Hiking we love the Findra Isla Merino blend vest top which is lightweight and coupled with a fine mesh for extra ventilation. Findra are another British brand, founded by Scottish Fashion designer Alex Feechan. Check it out below.

Findra Isla Ladies Merino Vest Top

Findra Women's Merino Isla Vest Top £38

Women's Base Layer Leggings

There are two main options for your bottom half, particularly if you are skiing or snowboarding. Either full length thermal leggings or a slightly shorter length, which is worth considering if you want a great fit with your ski or snowboard boot as it should finish slightly above the boot. Ski or snowboard brands have a whole range of different names for these slightly shorter pants, including 3/4 pants, 7/8 pants, Capri's or even "boot length!" Alternatively if you are looking for long thermal underwear then avoid these shorties! We've picked out two great choices below; the Patagonia Capilene Thermal Weight Boot-Length Bottom and the Eivy Ladies Base Layer Leggings in Orchard. The Eivy leggings are longer length, but fit well under a boot thanks to the fabric which although is brushed and warm on the inside, is stretchy and well fitting to ensure it doesn't ride up in a ski or snowboard boot.

Patagonia Boot Length Capilene Womens Thermal Leggings

Patagonia Women's Capilene® Thermal Weight Boot-Length Bottoms

Eivy Women's Thermal Leggings Orchard

Women's Ski All in One's or Ninja Suits

If you are looking for an all in one base layer then we have a couple of suggestions for you. The awesome brand Airblaster, from Portland, Oregon has turned what may have been considered the grown up version of a baby grow into a super cool, technical Ninja suit base layer. Made from a blend of super-fine Merino and Tencel has everything from a "pony portal" (for the pony tail of course!) to an easy pee-zy 350 deg waistband zip.

Mons Royale also stock a Merino Wool all in one they call a "Monsie" we can't wait for their new collection to land!

Women's Merino Ninja Suit Airblaster

Airblaster Women's Merino Ninja Suit

 Women's Base Layer Underwear

Gone are the days of wearing cotton pants from M&S and any old bra for your action sports! There has never been more choice of technical underwear. We are currently stocking the Mons Royale Merino Wool Bra which with a cross back design is lightly supportive and allowing a range of motion. Made from a Merino Wool / Nylon / Elastane blend it has all the great benefits of Merino listed above but also a decent amount of stretch to make it super comfortable.


We also love the Tribesports Thong made from a premium performance soft Nylon / Elastane blend. This has a luxury feel and is sweat-wicking and anti-bacterial and perfect for all sports.

Tribesports Pink Thong

Tribesports WomensThong Pink

And finally,

We've hope you've enjoyed our guide to women's base layers; if you think we have missed anything or would like to give us any feedback we'd love to hear from you hi@thelatitude.life. We have two other blogs in our base layer series so if you would like to know more about these specific topics then check them out!

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