Buyers' Guide -Baselayer Tops

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

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.

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.

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.

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.

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.