Glasgow Caledonian University Mountaineering Club Adventures: Selecting Your Warm Layer

There are many types of warm layer from a down jacket to a simple fleece. All have their uses alongside different advantages and disadvantages of the different material used.

Materials

Down - This is extremely warm and very expensive. But when it becomes wet or damp it loses most of its insulation properties. In Scotland down wouldn't be particularly useful as it will get wet quite quickly and therefore not be insulating in a short time. Down has its main use in the Alps or the Poles where it is dry rather than damp so the insulation isn't affected.
Synthetic - These are not quite as warm as down but in the UK this doesn't make a great deal of difference with the temperatures we get. When a synthetic material gets wet it can retain up to about 75% of its warmth. These are still expensive jackets but are worth investing in (normally called Belay Jackets). Synthetic jackets are useful as an extra layer to throw over all existing layers when you stop to add extra insulation to prevent you cooling down (this is useful especially in winter).
Fleece - This is the cheapest of the materials and the most useful, they are lightweight and can be packed away quickly. They can be layered on top of each other to increase the warmth. They retain most of their warmth if they get wet. While it is a synthetic fabric, it is separate in this list as it is not filled. Fleece Jackets are mainly useful as the Mid Layer of the layering system because of their insulating properties and the lightweight properties in comparison to other materials.
Wool - This becomes really heavy when wet and is not recommended at all for mountaineering with.
Softshell - Effectively this is a fleece jacket that is coated so that it doesn't let any air through and is water resistant (not waterproof!). This is versitile and very useful, it adds extra insulation properties to a Fleece and is still very lightweight.

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