Why Do Wool Diaper Covers Need to Be Lanolized?

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You may have heard how amazing wool is, especially when it comes to using it as a cover for absorbent cloth diaper parts.

Wool is famous for having antibacterial and antifungal properties – all thanks to lanolin which is naturally present in wool.

So why do you need to lanolize wool covers if lanolin is already present in wool?

Wool covers need to be lanolized every couple of weeks because lanolin wears off the covers because it neutralizes urine that comes in contact with it. Lanolizing wool is crucial for keeping the wool cover water-resistant and maintaining the wool’s antibacterial and antifungal properties.

Read more about why it is necessary to lanolize wool, how often you need to do it and how you lanolize wool.

Why Do We Lanolize Wool?

Lanolin is a wax usually secreted by sheep to help their coat stay water-resistant. It has antibacterial and antifungal properties. Thanks to lanolin, wool is naturally self-cleaning. Lanolin also keeps wool odor-free.

As such, it is valuable when wool is used as a diaper cover.

When lanolin comes in contact with urine, the lanolin fatty acids react with ammonia and neutralize it by forming a salt. The wool cover only needs to be air-dried after a diaper change, and the odor disappears.

This means that lanolin is continuously wearing off when you’re using wool covers, especially if the wool covers come in contact with a lot of urine.

Once the lanolin is all used up, wool covers will absorb the urine and start to smell.

This is why wool diaper covers need to be lanolized when lanolin is all used up.

Black wool diaper cover in a lanolin bath in a kitchen pot.

What Does It Mean to Lanolize Wool Covers?

Lanolizing wool covers means that new lanolin is reintroduced into wool to restore the natural state of wool.

Lanolin is usually introduced into wool by soaking wool covers in a lanolin emulsion, commonly referred to as a lanolin bath.

A few other methods are available, but they’re generally used to supplement the main way – soaking in the lanolin bath.

Other means of applying lanolin entail:

  • spot-rubbing lanolin onto a cover,
  • using a lanolin spray,
  • and using a lanolin-enriched wool detergent, which will save you at least one lanolization after washing the covers because the detergent won’t wash all of the lanolin away as wool detergents without lanolin do.

How Often Do You Need to Lanolize Wool Covers?

Wool diaper covers generally need to be lanolized every 2-4 weeks unless they get soiled sooner. This period depends on the absorbency of the cloth diapers underneath the cover and the amount of pee that comes into contact with the covers.

You’ll see it’s time to lanolize wool covers when they start to smell like urine after the diaper change, and the odor doesn’t disappear after about an hour or two. An even more obvious sign is a leak.

Read all about the reasons why your wool covers might smell and how to prevent this from happening to you.

Wool covers will last much longer if you use more absorbency underneath them.

For example, hemp fitted diapers (affiliate link to Amazon) are much more absorbent than a simple flat diaper (affiliate link to Amazon), meaning less urine will come in contact with the cover. After each diaper change, more lanolin will be left intact, and the wool cover it last longer.

The time passed between two lanolin applications is also highly dependent on the peeing pattern of your child.

Some children, especially when they grow older, start peeing a lot more at once as opposed to little trickles all the time when they’re little. The cover usually uses more lanolin to neutralize all the urine with so-called “heavy wetters”.

I have also noticed that a new cover won’t last as long without lanolization as a wool cover that has already been in use for a couple of months. I guess some of the lanolin stays inside the wool even after washing it, and more is added each time we lanolize.

If you don’t have time to wash and lanolize right away (because these two processes certainly are somewhat time-consuming), there are a couple of tricks to help you put off these two procedures.

One is to use a lanolin spray (link to Etsy store) that you spray onto the cover, and the other one is to use a wool liner (link to Etsy store) that you have previously lanolized. By placing it onto the cover, the lanolized liner will help you neutralize urine and keep the wool cover good for a week or two. A wool liner is probably a better idea for daytime wool covers because it will cover almost all the area of the wool cover. Since it won’t cover all the area of wool pull-ups (my definition of a nighttime wool cover), it might not be as helpful in those.

How Do You Lanolize Wool Covers?

Now that you know how important it is to frequently lanolize your wool covers, you’re probably wondering how to do this.

Always make sure you’re only lanolizing clean wool covers. This means you must wash them with a specialized wool detergent (affiliate link to Amazon) when you notice smells and/or leaks.

If you’re not sure how to wash your wool covers, here’s a detailed post that will help you get clean covers every time.

Some instructions say you should only lanolize dry wool, while others are fine with lanolizing wet wool.

I’ve always followed the directions on the wool covers I purchased, which state to dry the wool before lanolizing it. After the wool covers are dry, I go and lanolize them.

Pure solid lanolin.

For lanolization, you obviously need lanolin.

You can use pure solid lanolin (affiliate link to Amazon), commonly available in drugstores, or a dedicated already prepared lanolin emulsion.

Read this post about choosing the best lanolin for lanolizing wool covers.

Either way, you must prepare a lanolin bath for your wool cover(s).

If you’re using pure solid lanolin, you definitely need to read this post first – it will prevent you from ending up with lanolin spots all over your wool covers!

I won’t go into much detail here, so check out the above post, where I identified foolproof ways to prepare the lanolin emulsion so you won’t end up with lanolin patches all over your wool covers.

Ensure lanolin is completely emulsified and that the lanolin bath is no hotter than 30° Celsius/86° Fahrenheit because wool can felt and shrink if the water is too hot. I usually use a kitchen pot for the lanolin bath, but you can also use mason jars or any other appropriate containers at home.

Then turn your clean, dry wool cover inside out (the inside of the cover is the most important to be correctly lanolized) and slowly submerge it in the lanolin bath. Wool absorbs water very slowly, so you need to immerse it at a very slow pace.

A heavy plate over the lanolin bath inside the kitchen pot.

After the entire cover is submerged in the lanolin bath, I usually put a heavy plate over it to help keep it underwater. If you’re using a mason jar, fill it up, so the cover is entirely under water.

Keep the cover in the lanolin bath for about 3-4 hours, pour the excess fluid away and then roll the wool cover with a towel to press out excess water.

Then place the lanolized wool cover on a towel that’s put onto a drying rack horizontally. Remove the towel after a couple of hours to remove the moisture that’s keeping the wool covers from drying.

I turn the cover inside out and back every morning and evening until it’s completely dry.

Then it’s ready to be used!

I created a comprehensive step-by-step guide to lanolizing wool covers in this post, so 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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