How to Wash and Lanolize Wool Diaper Covers

Wool diaper covers stay waterproof because of lanolin — the natural oil in wool that repels moisture. Washing slowly strips the lanolin away, which is why wool covers need periodic lanolizing to keep working. The process is simple: wash only when needed, lanolize every few weeks, and the cover stays water-resistant for years. Here's exactly how to do both.

The basics

Why wool covers need lanolizing

Wool diaper covers work because of lanolin — the natural oil sheep produce to waterproof their own coats. When wool is processed into fabric, some lanolin remains in the fibers, giving the cover its ability to absorb moisture while staying dry on the outside. A well-lanolized wool cover can absorb up to a third of its weight in urine without feeling wet.

Lanolin slowly depletes with washing and use. Once depleted, the cover stops repelling water — you'll notice it feels damp on the outside after just one use, or that baby's clothing gets wet. Re-lanolizing restores the protection. It's the single care step that makes wool diaper covers last for years instead of months.

Frequency

How often to wash and lanolize

Wash: every 1–2 weeks

Only when the cover is visibly soiled or has developed odor that airing out hasn't resolved. Wool is naturally antibacterial, so covers can be aired between uses without washing.

Lanolize: every 2–4 weeks

Or after every 3–4 washes. Test by dampening a small spot with water — if it beads up, you're fine. If it absorbs, it's time to lanolize.

Air out: between every use

Between uses, hang the cover in a well-ventilated area. Fresh air and sunlight neutralize odor. This step alone extends time between washes significantly.

New covers usually need lanolizing before first use

Most wool diaper covers ship with varying amounts of lanolin depending on how they were processed. Disana and Reiff covers typically benefit from lanolizing before first use. Test by wetting a small area — if water beads up and rolls off, the cover is ready. If water absorbs into the fibers, lanolize first.

Products needed

What to buy

You need two products total. Neither is expensive, and both last a long time.

For washing: a wool-safe cleaner

Any wool-safe detergent works. Popular options include Eucalan (contains a small amount of lanolin, which helps maintain water resistance between full lanolizing sessions), mild unscented baby shampoo, or a dedicated wool wash from brands like SOAK or LANACare. Avoid standard laundry detergent — enzymes in it will digest wool fibers over time.

For lanolizing: pure solid lanolin

Pure solid lanolin is the standard choice. The same lanolin products sold for breastfeeding — Lansinoh and Medela are the most common — work well, are widely available, and are food-safe. A small tub lasts many months of regular lanolizing. Avoid anything scented or mixed with other oils.

Wool-safe detergent Pure solid lanolin Enzyme-free Unscented

Step-by-step

How to wash a wool diaper cover

Wash first, then lanolize separately. Doing both in one step creates uneven lanolin coverage.

Step 1. Fill the basin with lukewarm water

Fill a clean basin or sink with lukewarm water — around body temperature. Add a small amount of wool-safe detergent, mild baby shampoo, or a lanolin-enriched wool wash such as Eucalan. Agitate gently to dissolve.

Step 2. Submerge the cover

Place the diaper cover in the water and press gently to fully submerge. Do not rub, scrub, or wring — friction will felt the wool.

Step 3. Soak

Let the cover soak for 10 to 15 minutes. Swish gently once or twice. For soiled covers, a longer soak of 20 to 30 minutes is fine.

Step 4. Rinse

Drain the basin. Refill with clean water at the same temperature — sudden temperature changes can shock the fibers. Gently press the cover to release soapy water. Repeat with fresh water until no suds remain.

Step 5. Press out excess water

Lift the cover supporting its full weight. Press gently against the basin to release water. Do not wring or twist.

At this point, move directly into lanolizing if the cover is due for it, or lay flat to dry if it isn't. If drying, lay on a clean towel, roll and press to absorb moisture, then transfer to a second dry towel and lay flat.

Step-by-step

How to lanolize a wool diaper cover

Lanolizing is straightforward but the order of steps matters. Skipping the emulsification step is the number one cause of greasy spots.

Step 1. Melt the lanolin

Place 1/4 to 1/2 teaspoon of pure solid lanolin in a small heat-safe bowl or mug. Add 1/2 cup of very hot (just-boiled) water and a few drops of wool wash or baby shampoo. The shampoo helps the lanolin emulsify into the water. Stir until the lanolin fully dissolves and the water looks milky.

Step 2. Prepare the lanolin bath

Fill a clean basin or sink with lukewarm water — no warmer than body temperature. Pour the melted lanolin mixture into the basin and stir gently to distribute.

Step 3. Wet the cover first

Before placing the cover in the lanolin bath, dampen it in plain lukewarm water. Wet wool absorbs lanolin more evenly than dry wool, which can leave greasy spots.

Step 4. Soak the cover in the lanolin bath

Place the damp cover in the lanolin bath and press gently to submerge. Let it soak for 15 minutes to several hours — the longer the soak, the more lanolin absorbs. Overnight soaks are fine and often recommended for covers that have lost their water resistance.

Step 5. Press out and roll in a towel

Remove the cover, supporting its weight. Do not rinse — the lanolin needs to stay in the fibers. Press gently to release excess water. Lay flat on a clean dry towel, roll up with the cover inside, and press along the roll to absorb moisture.

Step 6. Lay flat to dry

Transfer to a second dry towel. Smooth the cover into shape and lay flat to air dry. Drying takes 12 to 48 hours. Do not use heat, direct sun, or a dryer. The cover is ready to use once fully dry.

Tip: let the lanolin cure

If you lanolize in the evening, the cover will be ready by morning of the second day. Don't rush drying with heat — not only does it risk damage, but lanolin bonds to wool fibers better during slow, gradual drying. A cover dried slowly at room temperature holds its water resistance longer than one dried fast.

Troubleshooting

Common problems and how to fix them

My cover is leaking

Leaking usually means one of three things. First, the lanolin didn't fully dissolve during lanolizing (parts of the cover were untreated) — re-lanolize with careful attention to the melting step. Second, the cover hasn't had enough lanolizing time — try an overnight soak instead of 15 minutes. Third, the cover has reached the end of its useful life and the fibers are too worn to repel water even with full lanolin — if re-lanolizing doesn't help, the cover needs replacing.

My cover has greasy spots

Greasy spots happen when lanolin didn't fully emulsify into the water before the cover went in — undissolved lanolin stuck to specific areas. To fix: melt a small amount of wool wash (no additional lanolin) in hot water, add to a fresh lukewarm basin, and briefly soak the cover to redistribute existing lanolin. Next time, make sure the lanolin mixture looks uniformly milky before adding it to the main bath.

The lanolin won't dissolve in hot water

The water wasn't hot enough, or there wasn't enough emulsifier. Use just-boiled water (not merely warm), and always include a few drops of wool wash or baby shampoo — these act as emulsifiers and are what allow lanolin (an oil) to blend with water. Without an emulsifier, the lanolin will separate back out no matter how hot the water is.

My cover smells even after washing

Most commonly either leftover detergent or ammonia buildup from urine. Try soaking the cover in lukewarm water with a tablespoon of white vinegar for 15 minutes, then rinsing thoroughly and lanolizing again. Vinegar neutralizes ammonia and clears detergent residue. If the smell persists after a full wash and re-lanolize cycle, the cover may need stripping — a one-time deeper clean with multiple rinses in hot (not boiling) water.

My cover shrunk

Shrinkage happens from heat, agitation, or both. Cool water, gentle handling, and flat drying prevent it entirely. If an item has shrunk, try a lukewarm soak with a small amount of hair conditioner, then gently stretch back to shape while damp. Some shrinkage is recoverable this way, but severe shrinkage is usually permanent.

FAQ

Frequently asked questions

How often should I lanolize a wool diaper cover?

Re-lanolize when the cover stops repelling water — you'll notice it feels damp on the outside after use instead of beading up. For most families using covers daily, that works out to every 2 to 4 weeks, or roughly after every 3 to 4 washes. There's no harm in lanolizing more often; over-lanolizing only makes the cover slightly greasy, which washes out.

How often should I wash a wool diaper cover?

Far less often than you'd think. Wool is naturally antibacterial, so a clean-looking cover can be aired out between uses and worn for 1 to 2 weeks before needing a wash. Only wash when the cover is visibly soiled with feces, smells even after airing, or has developed damp spots that won't dry. Most parents wash once every 2 weeks of regular use.

What lanolin should I use?

Pure solid lanolin is the standard choice — the same kind used for breastfeeding (Lansinoh, Medela) works well and is easy to find. Some parents prefer dedicated wool-wash products with built-in lanolin, like Eucalan or LANACare, which combine cleaning and lanolizing in one step but are less concentrated. Avoid anything scented or with added oils beyond pure lanolin.

Can I lanolize without washing first?

Yes, if the cover is clean. For a cover that's already clean but has lost water resistance, skip the washing step and go straight to lanolizing. Wash first when the cover is soiled, smelly, or has been in use for a few weeks. New covers usually need lanolizing before first use, as most ship without lanolin coating.

Why does my cover leak even after lanolizing?

Leaking usually means one of three things: the lanolin didn't fully dissolve during lanolizing (leaving parts of the cover untreated), the cover hasn't had enough lanolizing time (try an overnight soak), or the cover has reached the end of its life and the fibers are too worn to repel water. Re-lanolizing with a longer soak usually fixes the first two.

My cover has greasy spots. What went wrong?

Greasy spots happen when lanolin didn't fully emulsify into the water before soaking — the undissolved lanolin stuck to specific areas of the cover. To fix: re-melt a small amount of wool wash (without more lanolin) in hot water, add it to a fresh lukewarm bath, and soak the cover briefly to redistribute. For next time, make sure the lanolin mixture looks uniformly milky before adding it to the main bath.

Do new wool diaper covers need to be lanolized before first use?

Most do. Wool diaper covers ship with varying amounts of lanolin depending on the brand and how they were processed. Disana and Reiff covers typically benefit from an initial lanolizing before first use to ensure full water resistance. When in doubt, test by dampening a small area — if water beads up and rolls off, you're fine. If it absorbs, lanolize first.

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