Wool is nature’s performance fibre - warm, breathable and renewable. But when it comes to laundry day, even the most stylish wearers of wool find themselves Googling: how to wash a wool sweater. The good news? It’s easier than you think, and with the right care, your favorite knit can last for years - if not generations.
Wool Is Not Like Other Fabrics
Unlike cotton or synthetics, wool fibres have tiny scales on their surface - similar to the shingles on a roof. When wool is exposed to heat, moisture, and movement, these scales can open up and lock together. This process is called felting, and it causes the wool to shrink and lose its shape.
That’s why washing your wool pieces gently is so important - it can be the difference between a perfect fit and a child-sized jumper.
The Canadian Wool Council explains that wool felts when heat, moisture and friction cause the fibre’s outer scales to lock together - leading to irreversible shrinkage*.
How to Wash a Wool Sweater Without Ruining It
While dry cleaning is the recommended method for keeping your wool garments in top condition, we know it’s not always convenient. The good news? If you follow a few simple steps, a gentle cold wash at home can still care beautifully for your wool sweaters - without the risk of shrinking or misshaping.
Here's how:
- Choose your washing machine’s cold delicate or wool cycle.
- Use a pH-neutral wool detergent (we recommend using the Acca Kappa delicate laundry detergent).
- Set the spin speed to lowest or delicate - this reduces stress on the fibres.
- Place your sweater in a wash bag or pillowcase for extra protection.
- Lay flat to dry on a clean towel, reshaping gently and avoiding sunlight or heat.
Wool can absorb up to 30% of its weight in moisture without feeling damp, which is why drying flat is crucial - it prevents stretching while the moisture escapes *.
Because Merino wool is naturally odour-resistant, you likely won’t need to wash it after every wear. Airing it out between wears helps it stay fresh while preserving the integrity of the fibres.
Caring Between Washes
Knowing how to wash a wool sweater is one thing - knowing when not to is just as important. Airing it out after each wear and storing it properly will extend the time between washes and the life of your garment.
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Hang it outdoors (in the shade) for 30–60 minutes to freshen
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Use cedar balls or lavender pouches to deter moths (we recommend the Redecker Cedar Balls)
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Fold rather than hang to avoid shoulder distortion
Store your sweaters in a cotton pillowcase or breathable storage bag rather than plastic. Wool needs to “breathe,” even off-season.
What Other Guides Don’t Tell You (But We Will)
Sweater surgery:
Did your wool sweater shrink? You might be able to stretch it back. Soak it again in cold water with hair conditioner, then lay flat and stretch gently into shape*. (Not guaranteed, but sometimes worth a try.)
Cold soak refresh:
If your sweater doesn’t smell but feels limp, a cold water soak without detergent can revive its bounce.
Fabric resting:
Wool needs time between wears to “rebound.” Rotate between pieces if you wear wool daily - just like a good pair of boots. And because wool is naturally odour resistant, it doesn't need a wash after every wear - a simple airing out on a hanger, or near an open window, is all it takes to keep your knitwear feeling fresh.
Conclusion: A Little Care Goes a Long Way
Whether it’s your everyday essential or a treasured piece from the Iris and Wool collection, knowing how to wash a wool sweater is more than a domestic skill - it’s a quiet act of sustainability. When treated right, wool doesn’t just last; it improves with age, softening and shaping to your lifestyle.
By following these gentle washing steps and giving your knitwear the care it deserves, you’re not only preserving the fabric but honouring the craftsmanship, the grower, and the generations of women who’ve worn wool with pride.
Because at Iris and Wool, we believe fashion should be loved longer, worn more thoughtfully, and washed a little less.
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References:
* Canadian Wool Council - Wool felting – https://wool.ca/images/uploads/files/care/wool-fact-sheets-charcteristics.pdf
* International Wool Textile Organisation – https://iwto.org
* HGTV - Unshrinking a wool sweater - https://www.hgtv.com/lifestyle/clean-and-organize/the-secret-to-un-shrinking-a-wool-sweater
