Buyers' Guide -Baselayer Tops

Baffled by baselayers? Our latest Buyers' Guide will help you understand what baselayers do, the differences between the most common baselayer fabrics on the market, the pros and cons of different cuts and which type will suit you best.

When Berghaus surveyed walkers in the Lakes a few years back they found a good number were still wearing cotton tee-shirts under their expensive fleece and high tec breathable waterproofs.

This is a BAD THING. Cotton - think denim - soaks up water and holds it close to the skin, chilling your body and preventing sweat from evaporating through your layers.

Proper technical baselayer garments are designed to move moisture away from the skin and into your outer layers so it can be dissipated into the atmosphere. You'll stay drier, warmer and more comfortable and won't chill rapidly as soon as you stop. Dry clothing insulates better because water transmits heat more efficiently, so ideally you want to stay as dry as you can.

Your baselayer is there primarily to move moisture away from your skin, not to provide insulation - that's what your mid-layer is for.

Top tip We've found, all other things being equal, thinner baselayer fabrics move water across themselves and dry faster than thicker ones.

So what are we looking for in a baselayer?

• Wicking - the ability to move moisture out from the skin and spread it across the surface of the fabric so it can escape more quickly.
  
• Comfort - no one wants a hair shirt against their soft skin, so a soft, comfortable fabric is preferable.
  
• Anti-Stink - the best baselayers will resist odour for a day or more, the worst will pong unpleasantly after just a few hours use.
  
• Protection - although baselayers are often worn under other clothing, they can also become the outer layer, particularly in warm conditions, so sun protection may be a factor.

Top tip if you want to use a baselayer on a multi-day trip, anti-pong properties make life a lot more pleasant.

We've already touched on fit, but here's some more. Ideally your baselayer should fit closely enough to allow sweat to be soaked up easily. That means a snug fit will work best for most people, in really hot conditions though, it may be more comfortable to opt for a slightly looser cut.

Our favourite configuration is a long-sleeved top with a collar and a deep zip-neck. The sleeves can be rolled up for venting or rolled down for warmth or sun protection. A long zip can be opened for increased venting and a decent collar will help to protect the back of your neck from sunlight and chafing from other layers.

In all designs, check for flat-locked seams on the shoulders. They're flat and are far less likely to lead to discomfort under pack straps.

Check too for scratchy labels. Heat transfers that are simply printed onto the fabric side-step the issue neatly or cut them out carefully.

Top tip Long-sleeved zip-neck tops offer more versatility and are a good all-round choice. Look for flat-locked seams for comfort under pack straps.

FABRICS

There's now a wide range of fabrics out there, most have pros and cons, here's what to be aware of...

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Polyester

The most commonly used synthetic fibre is polyester. It usually wicks thanks to the structure of the yarn which has a different weave inside to outside helping to first move moisture then spread it out. It wicks very well and dries fast too.

Polyester doesn't have natural anti-pong properties, so it needs ether an anti-microbial treatment, which will eventually wear out, or silver impregnation like Xstatic, which is permanent and effective against smells.

As used by Lowe Alpine, Berghaus and countless others.

Excellent wicking, quick drying and can have good anti-pong properties. Petrochemical derivative, can smell if treatment not good.

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Polypropylene

Another synthetic fabric which works differently from polyester. Polypro' is hydrophobic meaning that it doesn't absorb moisture, so dries fast and moves moisture away from your skin, or at least doesn't hold it next to it.

It's best known as Helly Hansen's Lifa and used to have a real pong problem though that's now been largely solved, it can still get whiffy after a day on the hill. Also used by The North Face. In hot conditions can feel a bit plasticky.

Repels water and dries wickedly fast. Still needs washing after a day and arguable not as comfortable as polyester in the heat.

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Merino Wool

Merino is a feel good fabric in several ways. It's natural and renewable - comes from merino sheep - and ultra-fine fibres sidestep the itching issue you get with coarser wool making it comfortable next to the skin. It also has the handy property of feeling cool in warm conditions and warm in cold ones. Nice.

Merino works differently from synthetics. Rather than wicking moisture it can absorb lots of it while still remaining comfortable by holding it away from your skin and stil feels comfortable even when quite damp. That's great if you're a moderate to medium sweater, but if you run hot, you may be better off with a fast-wicking polyester top to move moisture away. Merino also takes longer to dry than synthetics.

As a bonus, merino doesn't pong and can be used for multi-day trips. It does develop a distinctive damp wool aroma when wet, but it's not unpleasant and not a problem.

There's more and more merino around, brands using it include Icebreaker, Smartwool, Rab, Embers and others. It is quite expensive though.

Comfortable, good moisture management, anti-stink properties, natural. Quite expensive, manages moisture rather than wicking it.

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Hybrids

A few companies use a mix of merino wool and synthetics. The idea is that the merino sits close to the skin for comfort and anti-odour while an outer layer of, say, polyester, moves the moisture away and outwards. The best of both worlds in theory.

We've found they can work very well - the Sportwool used by Macpac and Montane for example, and Odlo's similar arrangement - do seem to combine some of the properties of merino and synthetics, however the mix is crucial. One Helly version we tried combining polypro and merino actually seemed to offer the worst of both worlds, so choose carefully.

Synthetic and merino pluses in a single package. Hard to find, plus using the wrong combination can give disappointing results.

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IT'S YOUR CHOICE...

There's no absolute best choice, just what works best for you. In our experience, all the synthetics - polyester, polypro and Coolmax - work far better than a cotton tee shirt, though in general, the thinner the fabric the faster it will wick.

There are performance differences between different brands and types - we like Lowe Alpine's Dry Flo, Berghaus's Xstatic tops and GoLite C-Thru best - but any of them will be far better than a sodden tee.

We'd opt for a synthetic if you sweat lots and run hot or if you're on a tight budget.

The main alternative is merino wool we like the fabric a lot. It has natural anti-stink properties and remains comfortable even when damp or in hot or cold conditions. It's expensive though and strictly speaking, it doesn't wick though it will stay comfortable even when quite damp. It's also less hardwearing than some synthetics, we think.

Merino is great for cool to medium metabolisms and ideal for multi-day treks. It's also natural, though it's expensive with it.

Hybrids offer a bit of both and we like them as a good compromise choice.

Top tip Whatever fabric you choose, thinner ones will tend to be cooler and move moisture faster in the case of synthetics.

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MORE HELP AND ADVICE

This article should have given you some basic pointers. The good news is that there's a load more advice on OUTDOORSmagic:

Ask on the gear forum about general issues or specific items.

Check the member reviews section for user experiences of kit.

See OM editorial reviews on the front of the site for our impressions.

Ask Richard Gear if you have a specific question you need answering.