Why Do My Wool Covers Smell And What To Do About It

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Wool diaper covers are great because they’re natural, allow breathing, are biodegradable, and last so long without being washed.

But what does it mean when they start to smell like pee, ammonia, fish, or wet dog, as the users commonly describe the bad smells?

As a general rule, wool diaper covers start to smell when the amount of lanolin around the wool fibers isn’t sufficient to neutralize the urine fully. Additionally, using detergents that are incompliant with wool can cause different smells, especially if they aren’t rinsed thoroughly.

Read on for a more thorough explanation of the reason for the wool covers’ smell and how to solve the smelly situation so you can get back to comfortably using your wool covers as soon as possible.

A burgundy nighttime Disana wool cover.
A burgundy nighttime Disana wool cover.

When Do Wool Diaper Covers Start to Smell?

Not Enough Lanolin to Neutralize Urine

After all the lanolin has been used up (if a wool cover is lanolized correctly, it typically lasts 2-3 weeks), it won’t neutralize the urine anymore, and wool will absorb the pee and start to smell.

Learn here why wool covers need to be lanolized at all.

If your wool covers start smelling like pee after only a couple of days, you haven’t lanolized them correctly (you either didn’t use enough lanolin or emulsified it properly, so it wasn’t applied to the cover evenly).

If you’ve noticed lanolin spots on your wool covers, you need to change your lanolization method – read this post!

Read this post for a complete step-by-step guide to lanolizing wool!

Detergent Residue

Using a lanolin-enriched wool detergent (affiliate link to Amazon), you’ll save time by not having to lanolizing it after each use, which is as great as it sounds!

But it is possible that you’re not rinsing it thoroughly enough, especially out of fear of rinsing out the lanolin. As a result, you could get detergent residue in your wool, causing unwanted fragrances over time.

Detergent residue can also happen with detergents specialized for wool care and don’t contain lanolin. I recently washed a wool cover we’re using overnight with a detergent for delicate laundry (including wool), and I had to rinse the cover in at least four times the water quantity used for the wash itself.

I usually use a lanolin-enriched detergent for wool covers, but I had just run out of it, so I used this other wool detergent. The washing and rinsing water were quite murky, making me think I hadn’t been rinsing the lanolin-enriched detergent properly, leaving some detergent residue behind.

Also, ensure you’re not using too much detergent for washing your wool covers. Follow the instructions on the detergent label!

Not Using a Wool Specialized Detergent

If you’re using a regular detergent, especially the ones with bleaching agents, enzymes, and phosphates, you’re risking holes and deterioration of the wool fabric (source).

Holes are bad in a wool diaper cover but damaging the integrity of the wool fibers can make it harder to use as well. Wool might felt, shrink or become too brittle to be adequately lanolized, resulting in a smelly wool cover.

Leaving a Wool Cover Too Long without Washing

This one happened to me recently.

I’m rotating between three nighttime Disana wool covers (multiple stores sell Disana wool covers on Amazon – I linked to the cheapest one!). When one of them needs washing and lanolizing, I do that and use the next one until the second one needs washing and lanolizing.

(To be honest, two nighttime wool covers would be sufficient for alternating between them, but I have an extra one from when my older daughter and my younger son wore nighttime diapers simultaneously (they were similar in size). I was rotating three wool covers for two siblings, and it worked out nicely. Now that my older daughter doesn’t need them anymore, I’m left with an extra one.)

So I noticed that the wool cover I was using started to smell like pee a bit, and it felt more damp than usual in the morning. I decided to use the next cover over the coming days. I didn’t wash the cover right away (because I have three covers, I’m taking too much time to do this), and I hung it to dry.

Then an unexpected trip to the hospital with my son happened, and we were there for about two weeks. When we got home, my husband mistakenly used the nighttime wool cover that was supposed to be washed long ago, and it smelled very badly in the morning.

The wool cover smelled like fish!

I’m guessing this was a combination of old and new urine that got absorbed in the wool cover since no more lanolin could repel the moisture back into the absorbent fitted diaper.

The smell disappeared completely once I washed the smelly wool cover (this time right away!).

For a complete guide on washing wool diaper covers, check out this post – it’s all you’ll need for perfectly clean wool covers!

Why Do Wool Diaper Covers Last So Long without Being Washed?

Lanolin is a wax wool-bearing animals secrete (like sheep), whose primary role is to protect their coats from water (source).

Lanolin is composed mainly of waxy esters, lanolin alcohols, lanolin fatty acids, and lanolin hydrocarbons. When lanolin comes in contact with urine, the water will hydrolyze the esters into lanolin alcohols and fatty acids. The fatty acids will then react with ammonia in urine and neutralize it by forming a salt (source).

Because of its waterproof properties, wool covers must have enough lanolin around the wool fibers for them to not leak.

As long as there is enough lanolin in the wool covers, it will neutralize the urine, and the pee smell will disappear after a short while of airing the wool cover.

How to Make Wool Diaper Covers Last longer without Smelling?

Wool covers typically last a couple of weeks without a wash on their own, but here are a few tips to ensure you’ll get the most use out of your covers.

Add More Absorption

Wool can absorb up to 30 % of its weight in water. Luckily the lanolin is there to neutralize the urine and prevent urine absorption.

However, you can make the lanolin last longer by using more absorbent diapers underneath the cover, such as fitted diapers (affiliate link to Amazon), instead of pre-flats (affiliate link to Amazon). If you’re already using fitted diapers, consider adding a bamboo or hemp booster (affiliate links to Amazon) to increase absorbency.

This way, the absorbent diaper part will do the most of the job and leave more lanolin for next time.

Lanolize Properly

To ensure your wool cover will last at least 2 to 3 weeks before needing to be washed, you’ll need to lanolize it effectively.

Lanolizing typically needs to be done after every wash, except if you’re using a lanolin-enriched wool detergent (affiliate link to Amazon). Then you can skip the lanolizing step after every other wash.

Read this post about the best lanolin for lanolizing wool covers if you still don’t have one.

Use a Specialized Wool Detergent

Wool is a very different fabric from cotton and synthetics, which needs special care.

Always ensure you’re not using aggressive “heavy duty” regular detergents on wool.

Wool needs a very gentle specialized detergent (affiliate link to Amazon). These are usually marketed as intended for wool or delicate fabrics, so if you have one at home, use it.

Avoid Fabric Softeners

This probably goes without saying, but it’s worth stating it here.

Never ever use a fabric softener on wool!

Fabric softeners form an oily coating around individual fibers, making wool harder to breathe and regulating moisture, which is one of the best reasons to use wool covers.

Here’s a list of products you should never use with cloth diapers – check it out!


When I first became a mom, it shocked me how much more waste we produced by adding a tiny little member to our family. Since then, it's become very important to me to be more sustainable as a family. I'm excited to share with you what I'm learning along the way!

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