Merino wool is a great natural material that is at its best in outdoor sports clothes. I have used different merino wool clothes mostly on hikes, in trail running I have preferred more technical materials. However, merino wool has superior properties compared to technical materials, so I have increasingly turned to merino wool on the running side as well.
Based on my own experiences, here’s a post about merino wool clothing for outdoor enthusiasts, about the properties of merino wool and how you choose and care for merino wool clothing.
What is merino wool?
Merino wool is grown by a specific breed of sheep, the merino sheep. You can find merino sheep especially in Australia, New Zealand and South Africa. Merino wool fibers are long and merino wool has significantly finer grade compared to wool from other breeds.
Merino wool's best features are:
- Merino wool is moisture-wicking: it does not feel wet even when damp
- Merino wool is insulating and temperature-regulating: it warms in cold weather, but feels cool in hot weather
- Merino wool is odour-resistant: it does not start to smell, even if the garment is worn for a long time
- Merino wool clothing does not need to be washed often
- Merino wool clothing does not itch at all, even if other wool qualities do.
Merino wool clothing breathes and feels pleasant on the skin. Wool fibers can absorb large amounts of moisture without the garment feeling wet. Merino wool doesn't wrinkle much, so it's ideal for packing in a small bundle in a backpack.
A technical running shirt is lighter than a merino wool shirt when hiking. The light weight pleases a lightweight backpacker: I always take a technical running shirt with me on a hike, too. However, the technical shirt feels cold when it gets wet, and especially when the movement stops. It also quickly starts to smell bad. I often find myself switching to a merino wool shirt after hiking for a while.
Merino wool does not start to smell, even if you wear it for a long time. This is especially noticeable on long hikes with socks and underlayers. Antibacterial fibers absorb sweat from the skin and keep odors ‘locked’ until washing. Fewer washing times save energy and save nature.
Merino wool also repels dirt and is antistatic. In addition, wool is less prone to catching fire than synthetic fibers. Merino wool is perfect for exploring nature regardless of season!
Does merino wool itch?
Merino wool is a fine wool fiber that feels soft against the skin compared to other wool materials and is usually non-itchy. However, some merino wool clothes are softer than others, some merino knits, for example, are a bit rough.
My skin is particularly sensitive to different materials, detergent residues and, for example, the seams of clothes, but merino wool and silk do not irritate or itch. Merino wool is naturally elastic, so it is an excellent material for exercise and outdoor adventures.
Can you be allergic to merino wool?
It is a common belief that you can be allergic to wool, and people with a wool allergy should not wear merino wool clothes. It has been a common understanding that wool irritates atopic and sensitive skin. However, several studies have been conducted on wool allergy, and for example Zallmann et al. (2017) found no evidence that wool fiber is an allergen. Moreover, studies have found, that wearing merino wool may even improve atopic dermatitis.
Woolen clothes may contain chemicals such as formaldehyde, chrome dye residues and lanolin, which cause an allergic reaction. In addition, the roughness of wool can cause skin irritation, but similar irritation can also be caused by other materials, for example, acrylic.
High-quality and fine-fiber (superfine merino wool) and ultrafine-fiber (ultrafine merino wool) merino wool clothes probably do not contain lanolin or chemicals after the manufacturing process, and the wool fiber in them is so fine that it does not cause skin irritation.
Is merino wool ethical?
Merino wool is a 100% natural product. Merino wool does not contain environmentally harmful microplastics. When merino wool reaches the end of its useful life, it composts completely and quickly. Merino wool is a renewable natural material: sheep grow a new soft wool coat every year.
The Mulesing-free label means that no unpleasant surgical procedures have been performed on the sheep. When you care about animal welfare, always choose a mulesing-free merino wool product.
Is merino wool hot in summer?
Merino wool feels warm in cool weather, and cool in hot weather, like another natural material, silk. In the summer, especially, the combination of silk and merino wool is amazing when hiking, for example as a base layer top material or in long pants.
Merino wool clothing has several strengths. Light merino wool clothes are naturally suitable for summer. For example, my own base layer pants made of a mixture of merino wool and silk from Northern Playground are wonderful and just right for a summer hike.
In winter, thicker (200g/m2 and stronger) merino wool layers become necessary. For example, Icebreaker's 260g base layer is so comfortable that I sometimes wear its shirt with jeans just in everyday life. A thicker merino wool base layer comes along with me on hikes in late autumn, a bit depending on the weather in the Nordics.
The best merino wool base layer
Underwear, top and panties, can also be merino wool. Merino wool underwear is so comfortable for outdoor activities that I would never switch from merino wool to other materials.
Ordinary sports tops are heavy at the seams, feel sweaty and smelly after just one long run. The merino wool sports top fits like a glove and doesn't feel like you're wearing something extra. After an adventure in nature, the top is almost as fresh as when you left. The same applies even to a two-week hike: the merino wool top doesn't start to smell.
A merino wool base layer, a long-sleeved shirt and long johns, is the perfect choice for outdoor layering. When choosing a merino wool underlayer, you should pay attention to the thickness, cut and size of the merino wool.
The thickness of merino wool is indicated in grams per square meter. For example, the label 150g/m2 means a fairly thin knit, 260g/m2 means a thick and warm knit. In summer, a thin knit is enough, in winter the best merino wool base layer is of course thick, and the strength of merino wool is 200g/m2 and above.
The merino wool base layer should not have thick uncomfortable seams. Check that the garment has flat seams. The pricey merino clothes have separate wedge pieces in the armpits of the shirt and the crotch of the pants, so that even a flat seam does not hit your skin when moving. A highly sensitive person appreciates wedge pieces very much.
In order for a merino wool base layer to warm you in winter, it must be close to the skin. When considering the appropriate size, take into account how stretchy the knit of the product is. If the knit is very elastic or loose, you should choose a smaller size.
In winter, you should also try merino wool in the middle layer and possibly in the shell layer as well. You can also choose thinner and thicker merino materials for gloves, hats and headbands, depending on the weather and the purpose of use. The timeless classic, the merino wool tube scarf, is a great and versatile piece of equipment for outdoor exercise all year round.
Does merino wool last in socks?
Hiking socks are often put to the test, even if you use liners with merino wool outer socks. Both 100% merino wool and synthetic fiber reinforced hiking socks will probably either flake or get holes at some point if you hike a lot.
I haven't really noticed a difference in my own full merino wool or mixed hiking socks. In terms of durability, the structure of the sock has been essential, i.e. that the knit is very sturdy and the sock is reinforced in the right places.
I have also switched to merino wool socks in trail running. They feel lovely and light on the feet and don't start to smell. When trail running, the trail running shoes often get wet as well. A merino wool running sock doesn't feel disgustingly wet when the water runs inside the shoe, and it doesn't rub blisters even when wet. This is important especially on long runs. Even the thin merino wool running socks have lasted amazingly well.
Do you have to wash merino wool before use?
Absolutely not! Merino wool can be washed in the washing machine and most garments can be tumble dried. However, a tumble dryer is not necessary - drying woolen clothes on a flat surface saves both energy and the garment.
Sometimes washing merino wool clothing before the first use can be necessary. Particularly sensitive skin can be irritated by the roughness of merino wool, even though it is one of the softest wool fibers. Washing softens merino wool clothing, so after a few washes the merino layer can feel comfortable, even if it was itchy at first.
Merino wool clothing is a long-lasting piece of equipment, as long as you take care of it properly. On the other hand, even with good care, wool wears out. When you hike or run hundreds and thousands of kilometers of trails, your socks eventually wear out, and moths gnaw holes in merino wool long johns and tube scarves.
How to wash merino wool clothes?
Turn merino wool clothes inside out before putting them in the washing machine. First clean any loose dirt from hiking socks and other merino wool outdoor clothing, so that they do not remain inside the sock or block the washing machine.
Wash merino wool clothes with a wool or delicate washing program at 30-40 degrees according to the garment's washing instructions. 30 degrees is enough if there are no mega stains on the garment. Use a detergent intended for wool or delicate laundry. Fragrance-free bio laundry detergent that does not contain protease enzyme is great.
Do not use bleaching agents or fabric softeners, they weaken the properties of wool fibers.
Preferably dry merino wool clothes by laying them flat e.g., on a towel. Shape the garment by lightly stretching and straightening the side seams. When hanging, a woolen garment can stretch out of shape, and a knitted polo shirt becomes a nightgown. Avoid drying in direct sunlight or near heat. The heat may change the color of the garment.
Storage of merino wool clothes
Put the merino wool garment in fresh air for a while after use. You don’t have to wash the garment that often. Take advantage of the frost in the winter: just like oriental woolen rugs, merino clothes also enjoy hanging outside and snow baths in the cold!
After a long hike or adventure run, washing becomes necessary. Moths really like merino wool, and they are attracted by the scents left on the garment from human skin.
Keep merino wool clothes in an airy place. If you pack the garment away from use for a longer period of time, for example according to the season, use protective bags that bugs can't get into. For example, put cedar wood pieces in storage boxes or wardrobes. Though, you might still find a sweater or tube scarf that looks like a cheese one day.
Extend the life of your merino wool outdoor clothes by repairing the wear and tear. Holes can also be easily patched from socks and knitwear – who cares if outdoor clothes are not brand new!
P.S. The sheep in the picture are not related to merino wool clothing - they are sheep grazing near Lyngstuva in Lyngen, Norway!
