The Complete Guide to Wool Duvets

A wool duvet is a quilt filled with sheep's fleece rather than down or polyester. The reason to consider one is not warmth, because down is warmer for its weight. It is moisture. Wool takes up to a third of its own weight in water vapour out of the air and gives it back again, and polyester manages under one per cent. That single difference decides how the duvet feels at three in the morning, how often you have to wash it, and what you are sleeping under in year five.

This guide covers everything we know about them, including the parts that do not flatter what we sell.

In Australia a wool duvet is called a wool quilt or a doona. Same product, different word. New Zealand says duvet inner.

 

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Contents

1. How wool duvets actually work

2. Wool against down and synthetic

3. What GSM means, and what it does not

4. Loose fill against a bonded sheet

5. Why duvets go flat, and whether yours can be saved

6. Why wool quilts clump, and what the industry does about it

7. Certifications: organic, antimicrobial and hypoallergenic

8. How to wash and care for a wool duvet

9. Sizes, and the Australian problem

10. What to ask before you buy

 

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1. How wool duvets actually work

You lose water vapour through your skin and your breath all night, without sweating at all. It goes into the thin layer of air between you and the duvet, and what happens to it next is decided almost entirely by the filling.

Humidity, more than heat on its own, is what wakes people. Polyester has nowhere to put the vapour, so it builds up. Wool absorbs it into the fibre without ever feeling damp, then releases it back to the room as conditions change.

Everything else about wool duvets flows from that one property: why they smell fresh, why they need washing so rarely, and why they last.

What wool is not. It is not the warmest filling per gram. Down is, and nothing else comes close. And it does not have down's loft, which is why people are often surprised when a wool duvet arrives looking flatter than they expected.

 

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2. Wool against down and synthetic

Four fillings, not three, because synthetic comes in two forms that behave differently.

Short version. Cold, dry bedroom and you want minimum weight: down. Warm or humid bedroom, or you wake up too hot: wool. Tight budget: hollowfibre, and price it per year before deciding it was cheap.

→ Wool vs down vs synthetic: which duvet filling is right for you

→ The real problems with feather and down duvets, including the one everyone gets wrong

 

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3. What GSM means, and what it does not

GSM is grams per square metre: the weight of filling in one square metre of the quilt. It is the standard warmth measure in Australia and New Zealand.

The limitation. GSM measures mass, not warmth. Warmth comes from trapped air, so the fibre and the construction both change what any GSM figure delivers. Several major Australian quilt brands say this themselves in their own buying guides.

If you are unsure between two weights, take the lighter one. The choice is not symmetrical. A quilt that turns out too light is fixed with a blanket over the top. A quilt that turns out too warm cannot be made lighter.

→ What GSM should a wool quilt be?

 

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4. Loose fill against a bonded sheet

This is the distinction almost nobody explains, and it matters more than the brand or the price.

Loose carded wool. The wool is fluffed into a batt, laid into the casing and quilted into channels. The stitching exists to stop loose wool moving. It is a containment system, and containment slows migration rather than preventing it.

A bonded sheet. The wool is needle-punched into a single continuous web before it ever goes into a quilt: millions of barbed needles driven through stacked layers of fleece until the fibres lock into one another. No glue, no resin, no binder. What comes out holds its own shape.

The consequence is that there is no loose fill inside to drift toward the foot of the bed, gather in corners, or ball up in a washing machine.

 

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5. Why duvets go flat, and whether yours can be saved

"Gone flat" is three different problems and only one is permanent.

The 30-second test. Hold the duvet up to a window. Even translucent light throughout means the filling is where it should be. Dark dense patches with bright thin areas between them show you exactly where the problem is.

The cause behind all three is usually moisture. Damp synthetic fibres mat. Damp down clusters go sticky and clumpy rather than airy. Which is why hot sleepers wear duvets out faster: the duvet that overheats you is being destroyed by the fact that it overheats you.

→ Why duvets go flat, and which ones you can save

 

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6. Why wool quilts clump, and what the industry does about it

Wool clumps differently from everything else, and the difference matters.

Wool fibres are covered in microscopic overlapping scales. Heat, moisture and agitation make those scales lift and lock into each other in a ratchet-like mechanism that only works one way. That is felting, and Woolmark describes the process as irreversible.

So where a clumped down duvet can usually be shaken out, a felted wool quilt cannot. The fibres themselves have changed.

The industry's fix is chemical. Most wool sold as machine washable has been through a shrink-resist treatment, usually chlorine-Hercosett, which erodes the scales and coats the fibre in a polymer. It works. It is also rarely mentioned on the packaging, and it is why in this category you are usually choosing between untreated and washable.

The alternative is mechanical. Needle-punching locks the fibres together on purpose, in a controlled way, before the quilt is made. No loose fibres, nothing to felt into a lump, and no coating required.

→ Why wool quilts clump, and what the industry does about it

 

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7. Certifications, and three words worth distrusting

Organic. Certified organic wool quilts exist, usually under GOTS, which requires at least 95% certified organic fibre and audits the whole supply chain. It is a serious standard. It is also a farming standard: it says nothing about fibre quality, and less than 1% of New Zealand wool is certified, so lots are typically bulked from many farms. You often trade traceability for the label.

Antimicrobial. Wool does not kill bacteria. A 2022 peer-reviewed study tested untreated wool and found it neither kills bacteria nor inhibits their multiplication, despite passing the standard antibacterial test. Wool bedding that genuinely is antimicrobial has had an antimicrobial finish applied to it.

Hypoallergenic. There is no agreed definition of this word in textiles and no certification behind it. It means whatever the brand using it wants it to mean.

→ Is there such a thing as an organic wool quilt?

→ Is wool actually antimicrobial? What happened when someone counted

 

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8. How to wash and care for a wool duvet

Wash it far less often than you think. Wool holds odour compounds rather than releasing them into the air, so hanging it outside for an afternoon does more than a wash. Once a year is enough for most people, and a duvet cover does most of the work.

When you do wash it, remove any one of heat, agitation or roughness and felting cannot happen:

• Cold water. Heat is what lifts the scales

• Wool cycle, front loader, or a top loader with no agitator

• Wool detergent, no fabric softener

• A machine big enough that it tumbles freely, or trapped detergent causes its own clumping

• Dry naturally and thoroughly, flat if you can, out of direct sun. No heat in a dryer

• Gently stretch it back into shape as it dries

Storage. Clean, completely dry, loosely, in something that breathes. Never a vacuum bag, which crushes the loft.

 

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9. Sizes, and the Australian problem

New Zealand and Australian duvet sizes are not the same, and this catches people out.

The Australian Super King is 270 x 240cm, which is larger in both directions than the New Zealand equivalent. If you are buying across the Tasman, check the dimensions rather than the name.

If nothing standard fits your bed, and boats, caravans and antique frames rarely do, made-to-order is worth asking about. Not every maker offers it.

 

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10. What to ask before you buy

Five questions. None of the answers is on the label.

Is the filling loose or bonded? This decides whether migration is in your future.

Has the wool been shrink-treated? If it is loose fill sold as machine washable, it almost certainly has.

Has it been tested for chemical residue? Measurable, unlike "natural" or "pure".

Was it carbonised? Wool with a lot of plant matter is often treated with acid to burn it out. Clean wool does not need it.

Where is the wool from, specifically? A named region and named farms, or a country and a shrug.

 

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Where our duvets sit

Do Not Disturb makes wool duvets from New Zealand strong wool grown on NZFAP-certified farms around Gisborne, needle-punched into a single bonded sheet at Te Poi, then cut, filled and finished by hand in our Auckland workroom. Two weights, six sizes, and custom sizes made to order.

Nothing is added to the wool at any stage. No antibacterial finish, no biocide, no flame retardant, no shrink-resist treatment. Independent residue testing returned the same result as certified organic wool tested alongside it.

What they are not. Not the warmest duvet you can buy, since our heaviest is 350gsm where some brands go to 700. Not the cheapest. And they do not have the loft of down. If your bedroom is cold and dry and you want maximum warmth for minimum weight, buy down.

We have been making them unchanged since 2023, and in four years we have not had one fail.

 

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FAQ

Are wool duvets warm enough for winter? It depends on the weight and the climate. In New Zealand and the southern Australian states a 350 to 500 GSM wool quilt handles winter. In Queensland, Western Australia and the Northern Territory many people use 200 to 350 GSM all year, including winter.

Are wool duvets too hot for summer? A heavy one is. A 200 to 300 GSM wool quilt suits most summers, and wool's moisture handling makes it more comfortable in humidity than synthetic at the same weight.

Can you machine wash a wool duvet? Some, not all. Untreated loose wool generally cannot survive a machine, which is why most washable wool quilts have been shrink-treated. A needle-punched bonded sheet can be washed cold on a wool cycle without any treatment. Always check with the maker.

How long does a wool duvet last? Longer than synthetic, which typically lasts two to five years. Precise figures for wool are hard to come by and we are not going to invent one for ours.

Is a wool duvet good for allergies? Wool has no dust mite data either way, and we are not going to claim it. What is established is that synthetic bedding carries more dust mite allergen than feather, not less, so the common assumption that synthetic is the safe choice is not supported.

What is the difference between a duvet, a quilt and a doona? Nothing. Same product, different names. New Zealand says duvet inner, Australia says quilt or doona.

 

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Everything in this guide, in full

• Wool vs down vs synthetic: which duvet filling is right for you

• The real problems with feather and down duvets

• What GSM should a wool quilt be?

• Why duvets go flat, and which ones you can save

• Why wool quilts clump, and what the industry does about it

• Is there such a thing as an organic wool quilt?

• Is wool actually antimicrobial?