Wool School — Cloth Diapering Basics
Maybe a friend mentioned wool covers and you're not sure whether to take them seriously. Maybe you started researching cloth diapers, found a thread full of acronyms, and quietly closed the tab. Maybe you tried cloth before and it felt like too much laundry, too many pieces, or too many rules.
You don't need to know any of this before you start. Once you strip away the terminology, cloth diapering is actually pretty simple.
A note on pricing: cloth diaper prices vary widely and that's not a bad thing. Fabric content, custom dyeing, artistry, construction quality, and who is making the diaper all affect what something costs. A hand-dyed, small-batch fitted from an independent maker is a different thing from a mass-produced insert. Neither is wrong. Just know what you're buying and why.
A diaper has two jobs
Every diaper system needs to do two things:
Absorb moisture.
Keep that moisture contained.
Sometimes those two jobs happen inside one product. Sometimes they're separated into an absorbent diaper and an outer cover. Understanding that one difference makes everything else in cloth diapering much easier to follow.
The main types of cloth diapers
There are a lot of names, but most cloth diapers fall into a few basic groups.
Flats
A flat is a large piece of absorbent fabric that you fold around your baby. Simple, inexpensive, easy to wash, and quick to dry — different folds let you place more absorbency exactly where your baby needs it.
Prefolds
Similar to flats, but the fabric is already sewn into sections with extra layers through the centre. They can be folded around the body or folded into a pad and placed inside a cover.
Contours
A contour is an hourglass-shaped absorbent diaper that wraps around your baby — somewhere between a prefold and a fitted, taking the best of both. Like a prefold, it's simple and unfussy. Like a fitted, it has a shaped body that wraps around rather than lying flat.
Traditionally, contours have no elastic in the legs or waist and no closures. Some do come with leg elastic, which helps with containment, but a classic contour relies on the cover (or a Snappi or pins) to hold everything in place. They are not waterproof and always need a cover over top.
Contours can be made from any absorbent material — cotton, hemp, bamboo, or a combination. The soaker layer is usually sewn directly into the body of the diaper, though some have a snap-in soaker for added flexibility. They work well with doublers for heavier wetters or overnight use.
One thing worth knowing: without leg elastic, there can be some blowout risk if the cover doesn't fit snugly. Fasten them well and choose a good cover, because contours do loosen a little with wear. When the system works, it works beautifully — and they're one of the more customizable options out there because no closures means infinite adjustability.
Fitted diapers
Fitted diapers are shaped like a diaper and usually fasten around the waist. The key difference is that the absorbent material wraps around the entire body — front, back, sides, and centre — instead of sitting only through the centre. We call this 360-degree absorbency. A fitted diaper still needs a waterproof or water-resistant cover over top. This is where wool really shines.
Fitted diapers come with either a sewn-in soaker or a snap-in soaker. A sewn-in soaker is simpler to use; a snap-in gives you the option to remove it for faster drying or to swap in extra absorbency. Some fitteds fasten at the front with snaps or hook-and-loop; others fasten at the sides, which can give a trimmer front and a more adjustable fit around the waist and thighs independently. Side-snapping fitteds also tend to avoid "wing droop" — when the wings of a front-snapping diaper sag out at the leg openings.
Pocket diapers
Usually a PUL outer shell with a fabric lining and an opening where absorbent inserts are stuffed inside. Easy to put on once assembled and a common introduction to modern cloth diapering. The inserts come out for washing, which helps them get cleaner than if everything were permanently sewn together.
The pocket opening can be at the back (most common) or the front. A front opening is generally easier to stuff and lets you shake out a soiled insert without touching it. Some styles have openings at both ends — these are sometimes called sleeve diapers — so you don't have to pull the insert out at all before washing; it agitates loose in the machine.
One thing to be aware of with pocket diapers in hot weather: the synthetic materials used for both the outer and the inner lining trap heat. In very warm climates, some families find that natural-fibre options like fitteds or prefolds are more comfortable for babies playing outside in summer.
All-in-two diapers
A reusable outer shell with removable absorbency inside — either snapped in or laid in. When only the absorbent portion is wet, you can often replace the insert and reuse the shell for another change before washing the cover. Because the soaker isn't permanently attached, AI2s dry much faster than all-in-ones.
There's also a wool version of this concept worth knowing about: a wool cover with a snap-in or lay-in cotton or bamboo soaker. Everything breathes, nothing synthetic, and the cover can be aired between uses just like a standard wool cover. A lovely system if you can find one.
All-in-one diapers
The absorbency and waterproof outer layer are built into one piece. Convenient because there's nothing to assemble, but every layer needs to be washed and dried together each time. AIOs with soakers that are partially sewn in (rather than buried inside) tend to dry significantly faster than those with fully internal soakers — worth checking before you buy.
Hybrid diapers
A hybrid diaper uses a reusable waterproof cover with a disposable biodegradable insert. The inserts are made from natural materials rather than the plastics and chemicals in conventional disposables, and some are flushable. The cover gets reused; only the insert is discarded.
This is a genuinely useful option for travel, daycare, or any situation where washing isn't practical. Most hybrid covers also work perfectly well with a prefold or flat laid inside, so you can switch between cloth and biodegradable inserts in the same cover depending on the day.
Swim diapers
Cloth swim diapers have a water-resistant outer layer and a soft inner, but they're not designed to absorb — they're designed to contain. The key feature is strong leg and waist elastic. Most public pools and water parks require swim diapers, and a cloth version is reusable, more durable than disposable swim diapers (which can get mushy when wet), and usually just as cute as a regular bathing suit. A pocket diaper used without its insert works as a swim diaper in a pinch.
Training pants
Cloth training pants are made to look and feel like underwear but with enough containment for accidents during potty learning. Unlike disposable pull-ups, cloth trainers let children feel wetness, which is actually the point — that sensation is what helps them make the connection and want to get to the potty.
Pull-on styles work like underwear and are easy for kids to manage themselves. Snap-on styles unfasten at the hips, which makes cleanup easier if solids are involved. For overnight or longer stretches, pocket-style trainers let you add absorbency as needed. The basic rule is the same as with diapers: match the absorbency to what you actually need, and don't overthink it.
How fitted diapers fasten
Fitted diapers and covers come with a few different closure options, and people have strong feelings about their favourites.
Snaps are durable and stay put well. They take a little more effort to do up but don't wear out or catch on other laundry the way hook-and-loop can.
Hook and loop (sometimes called Velcro) is fast and easy, especially in those early newborn weeks when you're doing everything one-handed. The tabs do need to be folded back on themselves before washing so they don't grab everything in the machine.
Snappies are a popular alternative to old-school diaper pins. They stretch across the front of a flat or prefold and grip the fabric with small teeth — no poking, no fumbling.
Ties are the most traditional option and still used on some fitted styles, particularly hand-sewn or artisan diapers. They take practice but are simple once you've got the hang of it.
What is PUL?
You'll see this acronym everywhere in cloth diapering. PUL stands for polyurethane laminate — fabric that has been bonded with a thin waterproof layer. Most modern cloth diaper covers and many pocket and all-in-one diapers use PUL to contain moisture.
It works well. Wool simply approaches containment differently.
What goes inside — absorbency materials
Not all absorbency is the same, and understanding the difference between fibre types goes a long way toward solving leaks and getting a better fit for your baby's needs.
Cotton
Cotton is a fast absorber — it takes in fluid quickly, which is great for catching a sudden heavy wetting. The trade-off is that it can flood on a heavy wetter if there isn't enough of it or if it doesn't have a slower fibre alongside it to help hold the fluid in place. Cotton fleece is a notable exception: it's a heavier, denser absorber than soft interlock or stretchy cotton knits, and often handles higher output much more dependably.
Hemp
Hemp absorbs more slowly than cotton but holds significantly more. That makes it excellent for heavy wetters, longer stretches between changes, and overnight use. It's most effective when paired with a faster absorber like cotton on top — the cotton captures the initial rush while the hemp holds onto the volume underneath.
Bamboo
Bamboo fabric is soft, stretchy, and naturally grown, which draws a lot of people to it. It falls somewhere between cotton and hemp in terms of absorbency speed and capacity. Some families love it; others have reservations about the way the raw bamboo fibre gets processed into usable fabric, which involves a more intensive chemical process than you might expect from a "natural" fibre. Worth knowing going in.
Microfibre and synthetic inserts
Microfibre is inexpensive and widely available, and it's a common starter insert for pocket diapers. The downside is that synthetic fibres trap heat and moisture rather than breathing the way natural fibres do. They're also prone to compression leaks — when the diaper gets squeezed (sitting, car seats, being carried), the fluid gets pushed out rather than staying held. Many families start with microfibre and move toward natural fibres once they understand why things are leaking.
Why pair 360-degree absorbency with a wool cover?
This is what we consider one of the premium cloth diapering setups — and it's simpler than it sounds.
You start with a fitted or similarly full-coverage absorbent diaper underneath. That gives you absorbency around the body rather than relying only on a strip of material through the centre. Then a lanolin-treated wool cover goes over top.
The absorbent diaper handles the moisture. The wool provides the outer layer. They each have one job — and they can be cared for separately.
That separation has real practical advantages. The absorbency goes straight into your regular diaper wash without a PUL shell attached to it. Water and detergent move easily through the fabric, and there's nothing waterproof slowing the drying process. The wool cover, meanwhile, doesn't need to be washed every time the absorbent diaper does.
That means you invest in really good absorbency underneath and rotate a small number of wool covers on top.
Does a wool system cost more?
When people first see the price of a wool cover, they sometimes assume the entire system will be expensive. It helps to compare it against what a PUL stash actually looks like.
With PUL diapers — pockets, all-in-ones, covers — most families end up with 20 or more, and plenty have 50 to 100. Each one gets used and washed every single time, and the prints are genuinely so cute that the stash grows on its own. That's a real investment too, it's just spread across a lot of individual pieces.
With wool, three covers is a workable minimum. Five or six gives you much more breathing room. Some families do collect more because the colours are beautiful and it becomes its own kind of joy — but the baseline stash is small because the covers air dry and rotate rather than going into the wash after every change.
Your larger stash investment with wool is the absorbency underneath. Put more of your budget there, keep a small rotation of covers, and the system often ends up costing less overall than a full PUL collection.
Why full-coverage absorbency matters
Not all absorbency is arranged the same way. An insert or pad concentrates absorbency through the centre of the diaper. A fitted diaper surrounds more of the body with absorbent material.
That can be especially important for babies who are heavy wetters, sleep in one position for long stretches, move a lot, or need dependable overnight coverage.
The absorbency catches and holds the moisture. The wool is the backup and outer layer. That partnership is what makes the system work so well.
When your absorbency is doing its job, you're not asking the wool cover to compensate for anything. It's just there as the outer layer — doing exactly what it's designed to do.
Where Bumby comes in
Bumby makes the wool side of the system. Our covers are designed to go over the absorbency that works for your family — whether that's a flat, prefold, contour, fitted diaper, or another cloth system that could use an additional outer layer.
Some families also use wool over a disposable diaper when they want extra coverage, especially overnight. You don't have to replace everything you already own just because you want to try wool.
Wool bottoms — clothing and diaper cover in one
This is one of the oldest and most practical applications of wool in the diapering world, and it deserves its own mention.
Wool soakers, longies, shorties, and skirties are all garments that function simultaneously as outerwear and diaper cover. A pair of wool longies, for example, is simply a pair of pants — worn over a fitted diaper, they keep a baby warm, dressed, and covered all at once. No separate cover needed.
In cooler months especially, this is a genuinely magical system. One garment does two jobs. The baby looks like a baby, not like a diapering project. And because the wool is lanolized and breathable, it handles everything a dedicated cover would while also being the clothing layer for the day.
It's old-school in the best possible way — the kind of thing that makes you wonder why we moved away from it in the first place.
How wool works as a diaper cover
Wool behaves very differently from a laminated waterproof fabric. When treated with lanolin — the wax naturally associated with sheep's wool — wool becomes highly water-resistant while keeping all the natural properties that make it such an interesting fibre.
A properly lanolized wool cover can be aired between uses rather than automatically going into the laundry after every wet diaper. That's the part that surprises most people.
Your absorbency gets washed. Your wool gets reused.
Wool care is simpler than it sounds
Your Bumby cover arrives pre-lanolized and ready to use straight out of the package.
Between normal uses, let it air dry completely before putting it back into rotation. When it needs a proper wash, machine wash cold on a gentle cycle with a wool-safe detergent — we use and recommend Unicorn Clean (their heavier-duty wash, designed for cloth diapers). After washing, re-lanolize when needed and lay the cover flat to dry.
We have separate guides for washing and lanolizing, because once you understand how the diaper system works, those steps are much easier to learn in context.
How many diapers do you actually need?
This depends on how often you want to do laundry and the age of your baby. For the absorbent portion, many families start with a dozen or more and adjust from there. Newborns go through considerably more changes in a day, so a larger stash makes laundry more manageable.
For wool covers, three is a realistic minimum. Five or six gives you much more flexibility — enough to have one or two airing, one or two in use, and a spare on hand. Some families collect more over time because the colourways are beautiful, and that's a perfectly reasonable thing to happen.
You can mix diaper systems — and there are no rules here
There's no rule that says your entire diaper stash has to match. Lots of families use fitted diapers with wool overnight and pocket diapers during the day. Flats at home and disposables while travelling. Some use disposables most of the time and wool at night. Some use wool over a PUL system that was leaking and just needed a more forgiving outer layer.
That last one is worth saying clearly: wool works over PUL. If you've got pocket diapers or all-in-ones that are leaking and you're not sure why, a wool cover over top can buy you time and often solve the problem entirely. You don't have to commit to a whole new system to try wool. Put it over what you already have.
We're not here to tell you how to diaper your baby. We're here because we genuinely love wool and want to support whatever version of cloth — or not-entirely-cloth — diapering actually makes your life easier. No gatekeeping, no judgment about disposables, no pressure to do this any particular way.
If wool helps, great. If it helps sometimes, also great. Start with one cover, see how it fits into your life, and go from there.
Start with the part you want to solve
If leaks are your biggest problem — look at your absorbency first. Fibre choice and coverage matter more than most people expect.
If your absorbency is working but you want a different outer layer — explore wool.
If overnight diapering is the struggle — consider a hemp-and-cotton combination inside a full-coverage fitted, paired with a wool cover.
If you want clothing and a cover in one garment — look into wool bottoms. Especially in the cooler months, they're hard to beat.
If you have absolutely no idea where to begin — that's fine too. Start with the basics: absorbency underneath, cover on top. Everything else is just choosing which version of those two pieces works best for you.