Merino wool is one of the finest natural fibres on earth. It’s softer, lighter, and more breathable than standard wool. It does need a bit of care to stay that way, though - which is why we put together this guide on how to wash a merino wool sweater.

Aran Sweater Market has crafted authentic Irish wool sweaters for generations, so this isn’t the first time someone’s come to us for advice on properly washing a merino wool sweater - or how to dry a merino wool sweater. 

It's much simpler than you might expect. It just takes more work than your average sweater since we recommend hand-washing and special drying instructions. 

Can You Wash a Merino Wool Sweater?

Let’s get one thing out of the way - can you wash a merino wool sweater? Absolutely - and you should, when the time comes. The key takeaway from this overview of how to wash a merino wool sweater is that you can't treat it the same way as a cotton T-shirt or your favourite pair of socks.

Each strand of merino wool is covered in tiny overlapping scales, much finer than those on regular wool. That’s where merino’s wonderful softness comes from. They’re really vulnerable to damage from improper washing, though. 

Can you wash a merino wool sweater at home without a professional dry cleaner? Easily - you just need the right technique. It helps to know what the main risks are before we get into how to wash a merino wool sweater.

Risks of Improperly Washing a Merino Wool Sweater

Shrinkage is the biggest threat. Hot water and agitation permanently lock up merino fibres (a process called felting). There’s very little you can do to undo it once it's happened. 

Now, we do have a guide on how to unshrink a merino wool sweater if you've already pulled a favourite jumper out of the dryer only to find it two sizes smaller. But prevention is always the better path.

Washing a merino wool sweater incorrectly can also cause pilling - those small fabric bobbles that form on the surface. Again, we walk you through how to remove pilling from a wool sweater in our blog, but why not avoid the issues in the first place? 

Other risks include loss of shape at the neckline and cuffs, colour fading from harsh chemicals, and weakened fibres that shorten the garment's lifespan. This begs the question - is it possible to machine wash merino wool sweaters at all?

Should You Ever Machine Wash Merino Wool Sweater?

The follow-up to “can you wash a merino wool sweater” is usually “can I just throw it in the machine?” The honest answer: ideally not.

Some care labels do allow it. Lighter merino pieces can sometimes handle a gentle cycle. But should you regularly machine wash merino wool sweater items? We wouldn't recommend it. Even on a delicate setting, the drum's agitation stresses the fibres in ways that hand washing simply doesn't.

Here’s the quick guide if you absolutely must use a machine:

1. Turn the sweater inside out
2. Place it in a mesh laundry bag
3. Select cold water on the gentlest cycle
4. Use a wool-specific detergent
5. Skip the spin cycle if your machine allows it 

Hand washing takes roughly 10 minutes, though, and gives you way more control. The little extra effort is well worth it for a garment you've invested in.

How to Wash a Merino Wool Sweater: Step-by-Step Guide to Washing a Merino Wool Sweater (and Drying it!)

Right - on to the practical part. The whole process becomes second nature once you know how to wash a merino wool sweater by hand. Here's our tried-and-tested approach, the same method we recommend to anyone caring for a merino wool sweater for women or a men's merino wool sweater from our collection at Aran Sweater Market.

Pre-Treating Any Stains

Address any spots before submerging the whole garment. Apply a small amount of wool-safe detergent directly to the stain and let it sit for 5-10 minutes. Gently work it in with your fingertips. DO NOT aggressively scrub, as the friction can cause localised felting.

A mix of cool water and white vinegar (two parts water, one part vinegar) dabbed onto the stain works well even for stubborn marks like red wine or coffee. Let it sit, then proceed with the full wash. Read our full guide on how to remove old stains from wool sweater if need be.

Our Approach to Hand-Washing Merino Wool Sweaters

Fill a basin or clean sink with cool to lukewarm water (never hot). Add a capful of wool-specific detergent. Woolite Cold Water Wash works nicely, though any detergent labelled for wool or delicates will do.

Submerge the sweater and gently press it through the water. Let it soak for 5-10 minutes. The whole point of washing a merino wool sweater by hand is control, so resist the urge to wring, twist, or scrub. Just let the detergent do its work. We can’t emphasise this enough - gentle, gentle, gentle!

Drain the soapy water, refill with clean cool water, and press the sweater through again to rinse. You may need to do this twice. You're done when the water runs clear.

Let the Sweater Air-Dry Flat (Don't Hang it)

Learning how to wash a merino wool sweater is only half the story. Knowing how to dry merino wool sweater garments correctly is just as important, and it's where many people slip up. Never hang a wet merino sweater. The weight of the water stretches it out of shape, particularly at the shoulders and neckline.

Instead, lay the sweater flat on a clean, dry towel. Roll the towel up with the sweater inside to press out excess moisture - don't wring. Unroll, reshape the garment on a fresh towel or mesh drying rack, smooth out the sleeves, and leave it to air dry away from direct heat or sunlight. This typically takes 24-48 hours, depending on the knit's weight.

Does your merino feel a bit stiff once it's dry? Our guide on how to soften wool sweater fibres has a few simple tricks to bring that softness back.

Proper Storage Guidelines

Fold the sweater once it’s fully dry. Never hang it as this slowly but surely distorts the shoulders and stretches the fabric in exactly the ways that carefully washing a merino wool sweater prevents.

Store folded sweaters in a breathable cotton bag or on a shelf with decent air circulation. Cedar blocks or lavender sachets work brilliantly as moth deterrents without the chemical smell of mothballs. Have a read through our guide on the best way to store wool sweaters for more thorough seasonal storage advice.

Closing Thoughts on How to Clean a Merino Wool Sweater

Knowing how to clean merino wool sweater garments properly turns what seems daunting into something genuinely simple. And once you've sorted how to dry merino wool sweater items flat instead of hanging, your garment will stay soft, shapely, and looking sharp for years.

Every sweater at Aran is crafted from natural fibres in Ireland, carrying forward the knitting traditions that have defined the Aran Islands for centuries. Cable stitches representing the fishermen's ropes, honeycomb patterns reflecting hard work, and diamond details wishing prosperity. These garments tell a story that goes far deeper than fashion. 

Browse our 100% wool sweaters, from the merino wool cardigan range to our full selection of wool sweaters for women and wool sweaters for men. Every garment ships with a Certificate of Authenticity from Ireland, and we're proud to hold a 4.7 rating across nearly 50,000 reviews on Trustpilot. Discover the Aran Sweater Market difference today!

Frequently Asked Questions

Can you machine wash merino wool sweaters?

You might be able to get away with it, but hand washing is always safer. Machine agitation causes felting, which is essentially irreversible shrinkage. 

Does merino wool shrink in the washing machine?

Yes, often because of hot water and tumble drying. Even cold water on a gentle cycle won’t eliminate the risk altogether, though. We don’t recommend you machine-wash merino wool sweater items.

What happens if you wash merino wool with regular detergent?

Standard detergents can break down protein-based stains, and wool is a protein fibre itself. Always use a wool-specific or pH-neutral detergent when washing a merino wool sweater to avoid stripping softness and natural water resistance.

What should I wash merino wool with?

Woolite Cold Water Wash or Eucalan cleans without stripping the natural lanolin that keeps merino soft and slightly water-resistant. A mild baby shampoo works in a pinch, too. Just use something that explicitly says it’s made for wool fibres and you should be fine.

Can you use Dawn dish soap on merino wool?

It can work for spot-treating stains in an emergency but it's not formulated for wool and lacks the proper pH balance, so don't make it your regular go-to.