Most seasoned explorers as well as some militaries use the layering system when it comes to their clothing. The number of layers to be worn will be dependent on the climates they will be in. A good basic layering system would be: 1. Base Layer, 2. Mid Layer and 3. Outer Layer. The layers differ by function and most often fabrics.

The base layer is also called the next to skin layer. The main function of base layers is to transport/move the perspiration efficiently away from the skin. This will allow the skin to stay as dry and comfortable. It is also important that the base layer is a snug fit. A snug fit will allow the base layer to carry out its function. A loose fit acts the opposite. The fabric is not in contact with the skin, hence it cannot carry out its intended function of transporting perspiration away from the skin. Some of the good base layer fabrics are Merino Wool or synthetic fabrics like polyester, nylon, polypropylene, rayon or simply a blend of these. Spandex is often used in fabric blends to allow for a snug fit.  Depending on the climate we are preparing up for, base layer can also come in different ‘weights’. The technical parameter that is most commonly used to indicate the ‘weight’ is the grams per square meter (gsm) or ounce per square yard (osy). As a rule of thumb, the heavier weights are meant for colder climates while the light weights are meant for moderately cool climates.

The mid layer’s main function is to provide insulation. It traps heat and air. Air as we know is a bad conductor of heat, and this helps to retain the heat that is generated by our body within. As with base layers, wools, wool blends as well as synthetic fabrics like polyester fleece and polyester blends are some of the good mid layer fabrics. Another common and effective mid layer is the down jacket. The down jacket is very effective as its puffiness creates thousands of air pockets which help to trap heat.

Wools, wool blends and polyester fleece are good insulators and breathe well, but the compromise is that cold winds are more likely to blow right through. Laminated fabrics and down jackets on the other hand provide good resistance to wind and rain, but are not as breathable.

The outer layer is the layer that protects the wearer from the elements. Outer layers also vary the most from simple wind resistant jackets to waterproof breathable shells. There is a myriad of possible fabrics that an outer layer can be made up of. Majority of the outer layer fabrics are technical fabrics. Outer layers can be generally classified into hard shells and soft shells. Hard shells are usually characterised by ‘hard’ fabrics which emphasis durability and lamination of membranes on the underside of the fabric as well as featuring ‘water proof tapes behind seams. Soft shells on the other hand often incorporate stretch fabrics or ‘soft’ fabrics that are more breathable and have a more comfortable feel. Soft shells allow wearers to move more freely while providing some protection from the elements. The quality of the hard shells is typically reflected in the fabrics used, the membranes used as well as the amount of ‘water proofing’ done. Good quality hard shells can be breathable and yet waterproof. This can be achieved as water molecules are larger than water vapour. The membrane will not allow the water molecules to enter the hard shell but at the same time, allow the water vapour to escape. Some hard shells do not have membranes laminated to the fabrics. They achieve light water resistance and wind resistance by the tight weaving of the fabric. Both hard shells and soft shells typically are treated with Durable Water Repellent (DWR) which causes precipitation to bead up and roll off.

However, the lines between hard shell and soft shell are blurring. Advances made in fabric technologies have enabled soft shell fabrics to provide the same waterproof protection as hard shell fabrics. Designs from the various manufacturers are incorporating the using of both hard shell and soft shell fabrics into the same outer layer have also blurred the definition between hard shell and soft shell.

The layering system is one of the keys to enjoying outdoor adventures. It allows wearers to regulate their body temperatures so that they can remain comfortable and function comfortably. Whether you’re doing a high energy activity or a more sedate activity, layering allows you to slip layers on and off to stay comfortable. The number of layers and the choice of layers will depend largely on the climate and the type of activities which will be carried out. I hope this is useful for all the adventurers. Stay safe and stay warm!

Ethan Foo Chwan Chieh, Manager
Defence Systems