Let's look at base layers, some of the modern materials and their properties involves and how to best use them when climbing.

Ever had a day when you walked to the crag with your heavy climbing rucksack and arrived at the bottom to find your cotton T-shirt totally soaking wet, right down the middle of your back? Then, before you know it, the sun has disappeared, the wind is getting stronger and you're getting really quite chilled. So - what should you wear?

Wicking

If you're doing any form of high activity and you start to sweat, you need a base layer garment that actively removes (wicks) perspiration from your skin. Wet skin looses heat rapidly, and no matter how breathable your three-weeks wages worth of state-of-the-art Gore Tex jackets, it is like any system, only as good as the weakest link. If the weather gets fierce and you start getting wet, wearing your cotton T-shirt can massively increase your chances of getting hypothermia. Don't get caught out!

Features

Most base layers these days are made from natural Merino wool or manmade synthetic fabrics. There are pros and cons to each. Base layer garments should have the following features:

• Fast drying - essential for reducing heat loss and maintaining a high comfort level.
• Flat seams in areas that rub i.e. under the arms and around the waist.
• Comfortable against the skin.
• Anti-odour or anti-bacterial finish - this can become a major issue if you're about to spend a long time on a trip or expedition. Merino wool is less smelly than synthetic. Nowadays you can get synthetic tops with added silver ions, coconut husks and other miscellaneous items woven in to reputedly neutralise bacteria and the smell!

More tips

There are a wide variety of weights of fabric used for base layers. Which one you use depends on your chosen activity and the temperature you intend to use it in.

For hot summer days, or travelling to hot climates, a very lightweight top is key. They dry off more quickly and offer less warmth and bulk. Most manufacturers provide a Sun Protection Factor (SPF) rating with their garments so check these are suitable for you needs. Lighter coloured tops will absorb less heat so go for them in preference.

If you need more sun protection or if you require a more diverse and more durable fabric increase the weight.

For high activity sports look out for stretchy fabrics that work with your body and as the temperature gets cooler increase the thickness of your base layer. It helps if these are quite a close fit your body.

For winter sports with chance of limited activity, Micro fleece or Powerstretch can provide essential warmth. Powerstretch is an all time favourite for climbers in the winter. It has excellent freedom of movement and toasty warm properties. It can be used as a base layer with the brushed side next to your skin and smooth side sits on the outside allowing uninhibited articulation between layers. In the autumn and spring months wear Powerstretch as a single layer - it can give you that extra bit of warmth when you're cragging or bouldering, plus it's more wind resistant than most fleece materials and a lot lighter too.