How to choose the best thermals – natural vs. synthetic thermals

Thinking of getting some thermals?  Good move.  Whether it’s for cold-weather sports, keeping warm during exam time, pajamas for lounging in the winter holidays, or just to keep you warm in those in-between months where it’s a bit on the cool side…

The big question is, of course, which is better – natural or synthetic thermals?  Some people automatically choose one or the other – “crunchy” people (known for their habits of a big bowl of crunchy granola for breakfast!) will probably grab the natural thermals without any hesitation, whereas people who have lots of faith in the abilities of modern science to improve our culture will no doubt be choosing the synthetic thermal underwear every time.

However, it might pay for both parties to take a look a the benefits of each type of thermal underwear.  The boundaries between natural vs synthetic thermal materials are now so often blurred that to say one is better over the other is to argue over which is better, apples or oranges.  Before the natural crowd holler that thermals made with natural fibres are better because anything natural is better than anything synthetic, let’s remember that a lot of new textiles considered to be “natural” are actually processed so far as to render them no longer purely “natural”.

Bamboo, for example, is a textile which began its life as unfertilized and unsprayed bamboo canes, but once processed into today’s bamboo fabric, is now considered to be a rayon.  Rayon is a name for a type of man-made fibre which may or may not originally have been sourced from a natural plant.  You may find thermals and other clothes which are labelled “rayon from natural fibre”, which means that the fibres used once came from a plant.  It’s fairly safe to assume that fabric labelled simply “rayon” came from synthetic fibres in the first place – one example is recycled plastic bottles, an increasingly popular choice for textile producers, making a very soft fibre and recycled too thus saving on the environmental impact of the garments made.

However, for all this talk of bamboo and rayon and other fancy man-made things which it can’t be denied, are pretty clever – there is still a whole lot to be said for natural fibres and natural cotton or wool thermals. Caring for thermal underwear made of natural materials is not hard – just remember to put them through on a gentle (wool) wash cycle.

I say cotton or wool because these are the most common fibres that natural thermals are made from, but within these categories there are many variations.  Let’s start with cotton, since that’s pretty simple.  The cotton plant has been used for at least 7000 years, maybe more, for the production of textiles.  It’s easy for textile producers to get hold of, so it’s inexpensive, and it breathes well and doesn’t require extra special processing so it’s widely available. Cotton makes for comfortable and soft, and is generally used to line thermal gloves as well.

Thermals made from cotton are soft and comfortable, cheap and widely available.  However, they do have one major drawback.  They hold moisture against the skin, which makes them completely useless for outdoors sports and endeavours such as hiking, camping or hunting.  Anything which will cause you to sweat requires you to wear underclothes that wick the moisture off your skin, otherwise you are going to be a candidate for chafing, clamminess, and maybe even frostbite if are wet and in cold conditions.  You don’t want to get sick in the wilderness, so please, for outdoors endeavours, avoid cotton thermal underwear, not matter how inexpensive and tempting they may seem.

Thermals made from wool are considered among the best you can buy.  Wool thermals are very good at keeping the warmth in and wicking the moisture out.   That’s because wool has natural wicking properties and is also designed to keep a sheep toasty warm – so wearing wool will also keep you toasty warm!

Some new advancements have been made in the breeding of fleece animals in recent years, and some of the most highly prized wools are Merino wool (a breed of sheep), possum (they’re not bred, but New Zealand is getting into possum wool processing since possums are a pest there – beautiful warm wool!), cashmere (from goats) and alpaca.  Alpaca thermals are a luxury indeed, lending warmth and wicking and a touch of class as well.

Then there’s man-made or synthetic thermals.  Don’t forget that many synthetic thermals are actually a blend of synthetic man-made and natural fibres. bringing the two together to truly get the best of both worlds.  Although these may be the most expensive option, due to clever processing and smaller runs of the garments, you will undoubtedly be impressed by the qualities of these garments.