I plan to make some posts on clothing. Before I do so it is appropriate that I address the commonly encountered concept of “the Layering System”.
Many websites and books pay lip service to the Layering System. The problem is that this is usually oversimplified into a “lie to children” that omits important facets.
The typical version goes something like: “Your clothing needs to be in three layers. The under layer (buy some wicking underwear), the mid-layer (we sell really nice fleeces!) and the outer layer (have you seen our Gore-tex range?)”
Not technically false, but also lacking a lot of information you should also know.
The most important concept to grasp is that it is not the clothing that keeps you warm, but the air that the clothing traps. Several layers of thin garments may keep you much warmer than a single thicker (and possibly heavier) layer. The best insulation is still, dry air. Most materials that we call insulators serve to catch and hold such air.
I have addressed the topic of underwear in a number of other posts, so I will be brief here. Underwear is not just for wicking sweat off your skin surface. It is also there to prevent your body soiling the outer layers of clothing. Clean clothing traps air more effectively than that clogged up with oils, salt and other crud. Undergarments should be selected with of washing and quick drying properties in mind. Thin items will dry quicker than thicker. If it is very cold wear multiple thin layers of underwear. Carry a spare set of underwear. Depending on climate this may be simply a tee-shirt/ vest and a pair of underpants. Kephart tells us to change into our cleaner set for sleeping. If your underwear becomes sodden from exhaustion, change into the drier set. Use the dirty set to give your body a rub-down before donning the cleaner. Whenever practical, give the set your are not wearing a rinse or a wash. It may be prudent to change first if the set you are wearing is the dirtier.
This should actually be “mid-layers!”. A thick fleece jacket or jumper can only be on or off. This may mean a choice of too-cold or too-hot. Many of the mid-layer garments sold in outdoor shops tend toward being overly insulated. If your mid-layer is actually several layers of thin garments you have a more versatile system. This is likely to be warmer and lighter. Individual layers will be easier to wash and quicker to dry. Chances are you have a number of old shirts or thin jumpers that can be combined as very effective mid-layers. Minor damage or marks are not a problem in this role. Shirts may be more comfortable as mid-layers with the collars removed.
Your body may be sweating as well as producing heat. You want to get rid of this water vapour before it can condense, or even freeze. Even if there is metre-thick snow on the ground, vent your clothing occasionally to remove humid air.
The mid-layer(s) trap a layer of air that your body warms up. The outer layer prevents the wind blowing this warm air away, or the rain soaking into the mid-layers and displacing the air. Fleece jackets are often seen worn as the outermost garment. While this works with some models or under certain conditions, you will also find in other situations the wind will cut right through them.
You actually need a choice of outer layers. A rainproof is great if it is actually raining. In other conditions, even the breathable models may become clammy inside. Regularly venting your mid-layers is an important habit to acquire, even if you have top of the range breathables.
The more you wear rainproofs, the greater the likelihood they will be holed by thorns or other hazards. A few decades back “pac-a-macs” were fairly common. Rainproof garments that folded up into a small pocket or pouch when not required. These now seem hard to find and modern rainproofs tend to be more substantial, bulkier and more expensive. I have to think this may be a step backwards. On the other hand, some of the rain-ponchos on offer seem to be very light, compact and reasonable in price. They can also be used as groundsheets, shelters and so.
If you are not wearing your rainproof, you still need an outer layer that will retain the air your mid-layers are holding. Most cloths of a sufficiently tight weave can serve as a windproof. Most of your likely options are going to be cotton.
Cotton is not ideal as an outdoor material. If wool gets wet it retains most of its heat. Wet cotton is cold, and drains the body of heat trying to dry. While this is relatively well known, outdoor shops are full of cotton items they will try to sell you. Most military surplus items you may consider will be cotton. Cotton is easier to print in camouflage patterns, although the wide use of cotton in certain armies predates their adoption of camouflage. Most civilian, non-specialist items you might use instead of the above are also likely to be cotton.
You probably cannot avoid having some cotton items as your windproof layer. Sensible precautions are keeping a fire kit and rain-poncho on you. A change of clothing, carried in a waterproof bag, is also prudent.
For the lower body, cargo trousers and gaiters are a reasonable choice. The former can be modified as suggested elsewhere.
Combat jackets may seem a logical choice for the upper body. Their main problem is that in many conditions they tend to be too warm. You may be better basing your clothing system around a couple of bush-shirts, much as Kephart did. Field jackets and parkas can be added if the mercury drops.
A good bush-shirt may be cotton, but may also be found in fast-drying microfibres. Bush-shirts are a topic I will discuss in more depth in a future post. Relevant to today’s subject is that any shirt (or jacket) you plan to use as an outermost layer should be selected with room to wear several layers of insulation underneath. It should be at least a size larger than your usually wear. You should be able to comfortably wear it over a fleece jacket or NATO sweater, or their equivalent in thinner layers. In hot weather that space lets more air circulate.
As an aside, wearing a shirt over any insulation is a useful dodge to remember should you become separated from your jacket. A similar idea was to wear a combat jacket or bush-shirt over a waterproof jacket. This protected the waterproof from damage and reduced the noise that such a garment might make. It also might contribute to visual camouflage too. Although the outermost layer of clothing might get soaked, the waterproof kept the inner layers and wearer dry.
A few final points about the Layer System. The idea is that you can regulate or comfort and temperature by removing or donning garments as needed. Some means to carry unworn items will be needed. Stopping to change may not be practical. The rest of the platoon may not want to stand around while you redress, especially if your garment is under a mass of LBE and body armour! A common error in cold climates is to over-dress/ over-layer. If you are mobile, your level of clothing should ideally feel slightly chilly when standing around. Static roles such as sentry duty or manning foxholes will need more insulation. In any climate, do not neglect ventilation.