Regardless of age, gender or the nature of your daily work, a regular yoga practice is great for your body and mind. This type of activity opens up space to fully focus on your breath, get to know your body,
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Published: 12/15/2025💡 Tips|🚿 Clothing care
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How to wash thermal underwear? Practical tips and advice
How to wash thermal underwear to keep it in good shape for years to come? Explore proven methods and rules for washing thermal underwear that will help keep it functional for longer. With our practical tips, your thermal underwear will remain lightweight, breathable and comfy for many winter seasons to come, keeping you comfortable during training sessions and lounging.
Table of content
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👕 Gentle wash – wash by hand or in a washing machine at max. 30°C, selecting the sports or delicate cycle.
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🚫 No chemicals – avoid fabric softeners, bleaches, and enzymatic powders, which damage the fibers.
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🧴 Special detergents – use detergents designed for technical or sports clothing.
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🌬️ Dry flat – do not wring out or dry on a radiator; choose a well-ventilated, shaded place.
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🧦 Washing frequency – wash synthetic underwear after each workout, merino less often – after several uses, remembering to air it out.
🧺 How to wash thermal underwear – the most important rules
Thermal underwear - so what kind of pieces?
We could define thermal underwear the following way: Thermal underwear is a specialised type of clothing. Its main task is to effectively wick away sweat from the skin, which prevents the sensation of wetness and overheating during the exercise. So much for definitions. It has quite a number of advantages, and those who enjoy comfortable feel during their workouts - as well as athletes - love it for the fact that it keeps the skin dry during exercise and keeps you comfortable throughout the workout. This underwear is often called a ‘second skin’ as it clings to the body while allowing it to breathe and regulate body temperature.
Browse the thermal underwear category and choose your favourite model!
Washing thermal underwear properly is key to maintaining its properties and durability. Improper care can impair the material’s moisture-wicking capacity, shorten its life and diminish wearing comfort. Therefore, it’s worth knowing how to wash thermal underwear and being familiar with the rules that help keep the underwear in excellent condition.
How to wash thermal underwear? Practical tips
Washing thermal underwear requires a gentle approach and following a few important rules to preserve its properties and durability for longer.
Below we have gathered key information on the subject:
Hand-washing or machine-washing?
Hand-washing is the safest method, especially for delicate fabrics or underwear with the admixture of merino wool. Use tepid water and a special detergent, gently compressing the material. Avoiding rubbing and wringing.
Pro tip: for clothes made of merino wool, lanolin works better than a chemical detergent.
If you opt for machine-washing the underwear, always put it into a delicates wash bag. Choose a gentle or sports cycle, set the temperature to a maximum of 30°C and a low spin speed or go for a no spin option.
The right temperature
Wash thermal underwear at a low temperature, at a maximum of 30°C. Higher temperatures can damage the fibres and lose the thermal properties of the fabric as well as its breathability.
Detergents and laundry detergents
Use only detergents designed for washing technical or sports textiles. Avoid softeners and bleach, which can damage the fabric's structure and reduce its functionality.
Washing in a delicates wash bag
The delicates wash bag protects the underwear from mechanical damage and stretching during cleaning in the washing machine.
Follow these rules to ensure that your thermal underwear lasts for a long time and retains its properties even after many washes.
How often to wash thermal underwear?
It depends primarily on the frequency of use and the type of material from which it is made.
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Synthetic fabrics (e.g. polyester): wash this type of underwear after each intense workout, as sweat and salts can weaken the fibres and cause unpleasant odour. To ensure it retains its properties, wash the underwear even after wearing them really briefly.
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Natural fabrics (e.g. merino wool): underwear made of natural fibres can be washed less frequently, usually after several uses. Still, make sure to air it regularly. Frequent washing can damage delicate fibres and shorten the fabric’s lifespan.
Between washes, it is important to properly refresh thermal underwear - it is most recommended to air it outdoors. This helps remove unpleasant odours and moisture without the necessity to wash it every single time.
Drying and storing thermal underwear
Proper drying of thermal underwear is just as important as its proper washing, as the right methods allow the material to remain functional and durable for longer. Learn about the most important rules:
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Drying on a flat surface: After washing, gently squeeze off excess water but avoid wringing it out, as it can damage the fibre structure. Then spread the underwear on a flat surface, such as on a drying rack or a clean towel, which will further collect excess water. Such drying method prevents loss of shape and elasticity of the material.
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Avoid tumble dryers and heaters: High temperatures and the mechanical action of dryers are an easy way to destroy the delicate fibres and thermal properties of clothing. Drying next to a direct heat source, such as a radiator or dryer, is particularly harmful and should be definitely avoided.
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Drying in a well-ventilated place: For drying, choose a place that is shaded, cool and well ventilated so that the underwear can dry evenly. This will prevent unpleasant odours and bacterial growth.
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Storage: Storage conditions are just as important. Once the underwear is dry, store it in a well-ventilated place, avoiding cramped and damp spaces. Ideally, it should be loosely folded or hung on a hanger, which will keep its original shape and ensure unrestricted flow of air.
If you consistently stick to these rules, you will extend the lifetime of your thermal underwear and maintain its breathability and thermal insulation properties.
What to avoid when washing thermal underwear?
Want to preserve the properties and durability of thermal underwear? Avoid these few key mistakes when doing laundry:
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Enzyme washing powders - standard washing powders often contain enzymes and particles that can damage the delicate structure of thermal fibres by weakening the moisture-wicking ability and reducing the breathability of the fabric.
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Fabric softeners and bleach - these chemicals clog microporous fabrics, deteriorating their functionality. What's more, they can lead to faster material wear and loss of elasticity.
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Wringing out underwear - mechanical wringing causes the fibres to lose shape and contributes to premature wear. After washing, it is better to gently squeeze off the excess water without applying strong force.
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Drying at high temperatures - tumble dryers or warm radiators are another sins we tend to commit. Unfortunately, high temperatures destroy material structure, cause the fibres to shrink and lose their thermal properties. Thermal underwear is best dried flat in a well-ventilated, shady place.
Sources:
- https://www.skalnik.pl/blog/jak-prac-bielizne-termoaktywna/
- https://www.rowertour.com/blog/jak-prac-bielizne-termoaktywna
- https://brubeck.pl/blog/jak-prac-odziez-termoaktywna-najwazniejsze-porady/
- https://outdoorzy.pl/blog/jak-dbac-o-bielizne-termoaktywna
- https://esotiq.com/pl/pl/blog/jak-prac-bielizne-termoaktywna
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€22.90
The lowest price in the last 30 days before the reduction
€25.90
€22.90
The lowest price in the last 30 days before the reduction
€25.90
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€30.90
The lowest price in the last 30 days before the reduction
€34.99
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€30.90
The lowest price in the last 30 days before the reduction
€34.99
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€30.90
The lowest price in the last 30 days before the reduction
€34.99
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€19.90
The lowest price in the last 30 days before the reduction
€25.90
€42.90
The lowest price in the last 30 days before the reduction
€49.99
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€19.90
The lowest price in the last 30 days before the reduction
€29.99
❓FAQ – How to wash thermal underwear?
How to wash thermal underwear so that it retains its properties?
What detergents are best for washing thermal underwear?
Can thermal underwear be washed in a washing machine?
How often should you wash thermal underwear?
How to dry thermal underwear properly?
Can fabric softeners be used on thermal underwear?
How should thermal underwear be stored after washing?
How to remove stubborn odors from thermal underwear?
4F Editorial Team
The 4F editorial team is a group of experts who live and breathe sports and value an active lifestyle. Drawing on the experience of the 4F brand, we show that exercise is a source of energy, balance, and well-being. We provide reliable training advice, follow trends in sports fashion, and support our readers in discovering their motivation to take action.
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