On the whole, thermal underwear is fairly tough stuff. It stands up to years of abuse, and you can generally expect many years of service life from good quality garments. However, there are some basic tips that can easily help you increase the life expectancy, and the comfort of the wear that you get from your thermals.
Basically, there are three main factors that will destroy your thermal underwear.
1. Shrinkage. It’s a big problem especially with polyester and other synthetic underwear, especially because so many people use clothes dryers these days. Yes, you might lose a few pounds and fit back into it, but generally once the fabric has shrunk it won’t be a stretchy and comfortable any more.
2. Staining: Mainly this is an aesthetic issue, since nobody likes to wear tops with yellow armpits, can also be accompanied by persistent bad smells … potentially cutting short the life of a garment.
3. Pilling. This is when the fabric develops little rolls, or little pills of fluff, fibres and other bits and pieces usually picked up in the wash cycle. Not only is pilling unsightly, it also makes the underwear very uncomfortable to wear when these little rolls are on the inside.
So let’s go through some basic care instructions for different types of thermal underwear.
WOOLEN THERMALS: Merino wool is by far the best material available for robust and effective insulating underclothes. It is naturally antibacterial, and maintains good insulating properties even when it gets wet, and therefore makes the best long underwear for cold weather. It is very important to only ever wash woolen thermal underwear in a cold, or at most lukewarm wash cycle. Warm water causes wool to pull together and tends to permanently damage the garments. Additionally, you should not use normal washing powder or disinfectant to wash wool garments as this will cause the fibers to mat together like felt. Always wash wool garments on a gentle cycle, as excessive agitation will cause the fibres in the thermals to mat together, causing shrinkage and distortion. It will feel rough and uncomfortable, and won’t keep you as warm anymore.
If wool stains, hang it in the sun for a few hours, don’t use bleach or similar substances on it.
COTTON THERMAL UNDERWEAR: Cotton is generally a very forgiving fibre, and you can wash using normal detergent on a normal wash cycle, even in hot water if need be. Be aware that if you wash cotton in hot water it will shrink somewhat, but this is nowhere near as severe as for wool. Generally the biggest issue with cotton thermals staining, and Pilling. To avoid staining, the first thing you can do is wash your clothes on a regular basis. This might sound like common sense, but it really is the best way to avoid stainless. This includes not allowing a clothes to sit around for a week after you wear them before they go in the wash. Stains result from components in your natural perspiration which react with the air and other materials which are found already in the fibres. If you come home really sweaty, take your thermal underwear straight off and if nothing else drop them in a bucket of cold water to soak. This will immediately help draw the ammonia and other components of perspiration from the fibres, making them easier to clean later. The same goes for other stains from soil and dirt, on thermal clothing or otherwise. There are plenty of proprietary anti-staining products out there, or you can even use a mild bleach solution to get the garments white again. Alternatively, if you like a natural approach, you can simply wait for a sunny day and give the thermals a full day in the sun. The UV rays in natural sunlight are incredibly good at bleaching clothes to a bright white, and they are also able to kill any bacteria which may be lurking in the fibres.
In order to prevent Cotton thermal underwear from pilling, the best thing you can do is avoid washing them with any other clothes that are likely to shed a lot of fibres. Are the worst offenders tend to be bath towels and fluffy socks, both of which lose a lot of very fine fibres. Also, make sure you regularly clean the leaf filters on your washing machine. It’s amazing how to stuff accumulates in there, and once it overflows, it simply washes back and gets stuck on your clothes. While it is possible to shave the fine pills or fluff back off, it takes forever. Sometimes you can use strips of packaging tape to clean it off, and some people use electric shavers too. The to the inside out. Although washing things inside out is often recommended, this is to preserve the outer appearance. In the case of thermals, we are usually more worried about the inside since this will sit closer to the skin. So leave them the right way out when they go in the machine.
POLYESTER THERMALS: Caring for thermals made of polyester and other similar synthetic fibres is easy, because they are generally very hard wearing. They do not suffer from pilling or staining as badly as natural fibres do, but they certainly make up for it in their tendency to shrink very badly the greatest cause of shrinkage is excessive feet. It shouldn’t come as a surprise, since everybody has at some stage thrown a plastic bag or a plastic bottle in the fire. The first thing that happens? The item shrivels down into practically nothing, into a tiny ball of molten plastic. The same thing basically happens with fine synthetic fibres when they are heated, even to a low temperature of about 60°C. Never, never never put polyester thermal underwear in the dryer on a hot cycle!!! It will come out looking like dolls clothing, and you will never be able to wear it again. The best way to care for polyester thermal underwear is to wash them normally (they can handle warm water for normal detergent) and either air dry them, since they drive very quickly, or put them on a very low dry cycle. Acrylic and polyester thermal underwear and does not kill too badly, but you should observe the same rules as for cotton. Clean your lint filters regularly, and wash them the right way out.
What if your thermals smell bad? Don’t be embarrassed, it doesn’t mean you are a dirty person. Fabric worn close to the skin can easily develop BO smell even when well washed. As already mentioned, air drying especially in direct sunlight can be one of the best ways to overcome smells and stains in all clothes. You can also add a small amount of disinfectant (preferably a natural one like sphagnum moss) to the wash, and if you really want to nuke bacteria AND mold use some anti fungal product such as grapefruit seed extract. Personally I go for sunlight – Its still free, and leaves everything with a fresh fragrance and soft feel that you just cant duplicate.