These days they are referred to as a “base layer” and are usually made from some very scientific-sounding material and come with a big, obvious logo to satisfy status-seekers. “Plastic” is another name for what they are made of. Some of these may work while you are out in the cold, but I have found most of them uncomfortable, warm and sweaty when I come inside. Pile and fleece are also a type of plastic, but if it’s quite cold, they are hard to beat for a synthetic and aren’t as uncomfortably warm indoors.

Of course, whatever material is used, this layer should have zip openings to vent unnecessary heat. A minimum is the short zipper at the neck, but a full front zipper and underarm zippers are better. Tops should be more than long enough to tuck into the waistband of the bottoms. The bottoms usually come without zipper openings, but some higher-quality (more expensive) bottoms have a half circle zipper opening on the butt so any gender can take care of personal business.

When I first arrived in the Yukon in 1977, “fishnet” long johns were very common. The netting left an airspace next to your skin and they were actually quite effective. Sadly they were 100 per cent cotton and, as a result, were damp from perspiration almost all the time. Any cotton against your skin will become damp and may bring on hypothermia.

Polypropylene was, and still is, quite popular. It dries very quickly and works well as underwear, gloves, hats, socks or mitt-liners. It has also been relatively inexpensive. It has at least two negative aspects. Some brands provide you with the worst body odour you’ve ever experienced and, like all plastics, it melts and sticks to your flesh in a fire situation such as a tent fire, or an accident with an airplane.

Silk is very good to use against your skin. It comes in various weights in tops, bottoms, socks, hats, etc. It works well to keep the heat in and is also fairly comfortable to wear after coming indoors. The lighter weight silks are fairly fragile and are easy to tear or run, especially at the front of the knees.

Wool is probably at the top of the list as far as being versatile and dependable. If you can bear it next to your skin, coarse wool or nylon blends work well and are less expensive than high-tech stuff. Put it on over silk or even polypro to remove the “itch factor.”

Merino wool garments are expensive but very effective and do not itch at all against your skin. Merino comes with different brand names and also in various blends. The best is 100 per cent merino. It is a tough product and can be worn indoors comfortably in most situations. It rarely needs to be washed and does not cause you to smell badly. It can be washed on the “gentle” cycle in cold water and laid out on a flat surface to dry.

Pound for pound, down is the best insulator for clothing and sleeping bags. One downside is that down loses the ability to insulate when it gets wet. A the previously mentioned materials retain that capability when wet. They also also allow for some air circulation (breathability) while down is usually in a double-walled nylon sleeve that prevents any air circulation.