No. Wool does not kill bacteria and does not stop them multiplying. That has been tested directly, by counting the bacteria rather than looking at a plate, and the result was unambiguous.
Wool does pass the standard antibacterial test, which is why almost every wool bedding brand, including some of our suppliers and competitors, describes it as antimicrobial. It passes for a reason that has nothing to do with killing anything, and the reason is genuinely interesting.
We sell wool bedding. We are telling you this anyway, because the thing wool actually does is more useful than the thing it is credited with.
Where the belief comes from
Nobody invented this out of nothing. It comes from an observation anyone who has worn a merino base layer will recognise: wool clothing does not smell the way synthetic clothing does.
Odour in worn fabric comes from the activity of skin bacteria. So if a wool shirt smells less after three days than a polyester one does after one, the obvious explanation is that the wool is doing something to the bacteria.
It is a reasonable inference. It is also, as it turns out, the wrong one.
How the standard test works
The test is ISO 20645, an agar diffusion plate test, and it is the method behind most antibacterial claims on textiles.
A fabric sample is placed on a plate of nutrient agar that has been inoculated with bacteria, usually a gram-positive and a gram-negative strain. It is incubated at 37°C for 24 hours. Then the sample is lifted off and you look at the agar underneath.
A clear patch under the sample means no bacteria grew there, and the fabric is recorded as having an antibacterial effect.
Wool produces a clear patch. Across the tested organisms it rated a good effect, outperforming cotton and gauze.
One detail worth knowing. The standard was written to evaluate antibacterial treatments applied to textiles. Accredited laboratories describe it as applicable to fabrics with hygienic finishes or with antibacterial products incorporated in the fibre. It was never designed to assess whether a plain untreated fibre has the property on its own.
What one research team did differently
In 2022, researchers at the University of Zagreb, working with Université Grenoble Alpes, ran the standard test on untreated wool and cotton and then did something the standard does not ask for.
They lifted the fabric off, washed the bacteria back out of it, and counted them. At one hour, and again at 24 hours.
What they found
The bacteria were all alive. And there were considerably more of them than at the start.
The published conclusion is not hedged: it was shown without a doubt that neither textile material kills bacteria or inhibits cell multiplication. Both wool and cotton allowed bacteria to multiply freely over the 24 hours, while both were simultaneously producing the clear patch that certifies a fabric as antibacterial.
The real mechanism, which is better than the myth
Here is what is actually happening.
Bacteria do not simply sit on wool. They attach firmly to the fibres and build a biofilm as they multiply, anchoring themselves into the fibre surface. The researchers used X-ray microtomography to image the samples and found that how strongly bacteria attach depends on the surface topography of the fibre, which is why wool holds them more effectively than gauze does.
So when the sample is lifted off the agar plate, the entire colony comes with it, still attached to the wool.
The clear patch is not a graveyard. It is where the wool picked everything up and carried it away.
The authors note a genuine consequence of this: certain textiles, wool in this case, could exhibit antibacterial properties by removing excess bacteria that grow at the textile and skin interface when taken off the body. That is a real effect, and it is one reason wool clothing stays fresher. It applies rather better to a jumper you take off than to a duvet sitting inside a cover.
So why does wool not smell?
Because it holds the smell rather than the bacteria producing it.
The same paper points to the alternative explanation and describes the evidence for it as strong: wool bonds or adsorbs odorous fumes without inhibiting bacterial growth. The volatile compounds that make a fabric smell are absorbed into the fibre rather than released into the air around you.
This is more useful than an antimicrobial claim would be, because it explains something you can actually act on. Hang a wool duvet outside for an afternoon and the trapped compounds release, which is why airing a wool quilt works so well and why it needs washing far less often than people expect. That is not a marketing claim. It is the mechanism, and it is why our care instructions say what they say.
Who can legitimately claim antimicrobial, and how
Some wool bedding genuinely is antimicrobial. There is no mystery about how.
They add something. Applied antimicrobial finishes are a well-established textile technology, sold under registered trade names, and a manufacturer who applies one has bought the right to the claim. One of the largest Australian wool quilt makers does exactly this and is open about it in their product information.
That is legitimate and it is not what most shoppers think they are buying. The customer reads "antimicrobial wool" and understands it as a property of the wool. It is a property of the chemistry applied to the wool.
If you want a genuine antimicrobial claim on a wool quilt, you are buying treated wool. There is no third option, and untreated wool will not give it to you no matter how many labels say otherwise.
Why we will not claim it
Do Not Disturb makes wool duvets with nothing added to the wool. No antibacterial finish, no biocide, no flame retardant, and no shrink-resist treatment. Known in Australia as a wool quilt or doona.
That is the whole position, and it means we are not entitled to an antimicrobial claim. We could buy one tomorrow by having the wool treated, and then we would have to stop saying the thing we most want to say about it.
So we would rather be accurate about what wool does. It holds moisture and releases it. It holds odour compounds rather than letting them sit in the air. It needs airing more than it needs washing. None of that kills anything, and none of it needs to.
What this means when you are buying bedding
Treat "antimicrobial" on a wool product as a question, not a feature. Ask what was applied to make that true. If the answer is that it is a natural property of wool, the company either has not read the research or is hoping you have not.
Do not confuse it with hypoallergenic either. That word has no agreed definition in textiles and no certification behind it. We wrote about the related problem with the word organic in is there such a thing as an organic wool quilt.
And bacteria will grow on your bedding regardless. They grow on wool, on cotton, on polyester and on down. That is not alarming, it is why bedding gets washed and aired, and any material claiming otherwise has had something added to it.
What this means for you
If you are choosing wool bedding for its odour resistance, that is well founded and the mechanism is real. If you are choosing it because you believe the fibre is killing microbes, it is not, and no untreated wool product is.
The useful questions are what has been added to the wool, and what the material does on its own. Wool manages moisture extremely well and holds odour compounds extremely well. It does not need to be a disinfectant to be worth sleeping under.
FAQ
Is wool antibacterial? Not in the sense the word usually implies. A 2022 study tested untreated wool against the standard method and found it neither kills bacteria nor inhibits their multiplication. It does pass the standard test, because bacteria attach to the fibres and are carried away when the sample is lifted, which leaves a clear zone that reads as an antibacterial result.
Why do wool bedding brands say it is antimicrobial then? Some have had the wool treated with an applied antimicrobial finish, in which case the claim is true and belongs to the treatment. Others are repeating the standard test result without knowing what it measures.
Does wool resist odour? Yes, and this one is well supported. Wool bonds and adsorbs the volatile compounds that cause odour rather than releasing them into the air. It is why airing a wool quilt freshens it so effectively and why it needs washing far less often than other bedding.
Does that mean bacteria grow on my wool duvet? Bacteria grow on all bedding, whatever it is made of. Wool is not special in either direction here. Airing it regularly and washing it occasionally is the answer, as it is for everything else on your bed.
Is wool hypoallergenic? There is no agreed definition of hypoallergenic in textiles and no certification standard behind it, so the word means whatever the brand using it wants it to mean. We do not use it.
Sources
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Ivanković T, Rajić A, Ercegović Ražić S, Rolland du Roscoat S, Skenderi Z. Antibacterial Properties of Non-Modified Wool, Determined and Discussed in Relation to ISO 20645:2004 Standard. Molecules, 2022; 27:1876. DOI 10.3390/molecules27061876.
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ISO 20645:2004, Textile fabrics, determination of antibacterial activity, agar diffusion plate test.
A note on the limits of this. This is one study, testing six organisms on a woven wool fabric rather than on duvet filling. It is the only study we are aware of that counted the surviving bacteria rather than reading the plate, which is why we regard it as the better evidence. It is not the final word on wool and microbes, and we will update this if better work appears.
