Not all inserts and boosters are created equally. As well as the multitude of shapes and sizes, covered here, you might also need to consider what your inserts and boosters are made from. For brevity from here on in I’m just going to talk about inserts, but the same is true of boosters too.
There are five common fabrics used in nappy inserts. Each one has it’s own pros and cons. Sometimes they are blended together in an insert so you can get the benefit of each, whilst hopefully counteracting the disadvantages.
Below is a rough guide to the main fabrics, although remember that within each category inserts will be of varying quality and so it’s not simply the case that X will always be better than Y.
Certainly the cheapest fabric to manufacture, and therefore often included in some of the more affordable nappies. It is entirely synthetic, which is why it is cheap to produce. Microfibre cannot be placed directly against your baby’s skin as it will pull the natural moisture from their skin and make the area very sore. The microfibre fibres are also little hooks meaning they will scratch the skin’s surface which is why it feels a bit funny on your hands. Either stuff microfibre in a pocket, or place something else (either another booster or a liner) between the microfibre and your baby.
It is quick to absorb and holds a lot of liquid but prone to compression leaks, this can be overcome easily by adding a natural fibre to counteract the leak. Microfibre inserts do not require any prepping before use, just one wash to remove manufacturing residues and you’re good to go. It will also dry very quickly.
For me the biggest drawback is the shedding of micro plastics during the wash process.
Also a very affordable option. This is a natural fibre, although that doesn’t mean it is not extremely resource-intensive to grow and produce. Comes in a variety of types such as Birdseye, Terry towelling, or waffle weave. Look for organic cotton if you can afford to as that will not have been bleached. It can suffer from wear and tear, especially on edges of fabric where more friction will occur, bobbling is common too on flat weaves, although this is just a cosmetic issue. Those in hard-water areas will find it goes crispy after multiple washes. It will instantly soften once your baby wets the nappy, but if this bothers you then you can shake the nappy or rub it against itself once dry to soften it up. If there’s no elastics or PUL to worry about then it can be washed up to 90c and tumble dried.
It is the fastest absorber, you only need to try clear up some spilt water to see just how readily and easily cotton absorbs. Due to the natural oils it will require multiple washes to bring it up to full absorbency, up 10 washes in some cases. Overall I think cotton is very underrated from an absorbency perspective, although predominantly cotton nappies may not last for multiple babies due to wear and tear.
A more expensive option but one that has increasing popularity. Bamboo is obviously a natural plant and requires fairly low resources to grow. It is the manufacturing process to turn this plant into a fabric which is resource intensive and involves a multitude of chemicals. Therefore it is considered a processed fibre although it originates from a plant. Bamboo is normally blended with another fabric, this other fabric is key to how you can except the insert to perform. It has good absorbency, although not particularly quickly.
Bamboo is very soft to touch, although it will go crispy in hard-water areas this is not to the extent of other fabrics. Care must be taken not to dry bamboo against direct heat, such as a heated airer or radiator as this can damage the fibres. Prone to some shrinkage during washing, ensure you reshape inserts whilst damp to minimise this. Bamboo inserts will require to up 5 washes to reach full absorbency. Overall the biggest benefit for bamboo is its softness.
The most expensive fabric. Normally blended with cotton (at around a 45:55 hemp:cotton ratio), but sometimes bamboo instead. Hemp is the most absorbent fabric and locks that moisture in well. But it is slow to absorb and can harden so blending it with another fabric helps to counteract these issues. It is a natural material but a lot less resource intensive to grow compared to cotton, and less resource intensive to produce compared to bamboo.
Also prone to shrinkage from washing, ensure you reshape inserts whilst damp to minimise this. Because of how well hemp holds onto liquid you will need to ensure you have your wash routine nailed as without sufficient washing it is more likely to retains smells. I’ve never personally had an issue despite using hemp heavily for over a year. Due to the natural oils hemp inserts can take up to 10 prewashes to reach their maximum absorbency.
Often marketed as a bamboo insert with odour reducing properties (which isn’t actually true). Being dark grey in colour they will also hide any stains. Typically they will have a soft fleece outer which also acts as a stay-dry layer for your baby. This fleece outer is made from bamboo nanoparticles with are heated to an extremely high temperature to burn them. Hence charcoal bamboo.
In reality these inserts are often just microfibre. Of course microfibre has it’s place, but if you’re purchasing charcoal bamboo and expecting bamboo qualities then you may be disappointed.
Underneath the outer fleece (which is bamboo as such because it is made from bamboo nanoparticles) the absorbent layers are normally microfibre. Manufacturers can get away with calling them ‘charcoal bamboo’ because that is a correct (albeit slightly misleading) description of the outer fleece. But this fleece does not have any of the properties you might typically associate with bamboo, such as good absorbency, because it’s a fleece. And as I mentioned above it is a stay-dry layer so isn’t going to be absorbing anything.
There are of course actual charcoal bamboo inserts available. These have the same charcoal bamboo fleece, but inside the insert are layers of bamboo not microfibre. These will perform in the same way as a normal bamboo insert. It benefits from having a soft stay-dry layer but this also adds an extra bit of bulk so consider whether you need inserts that are able to go directly against the skin.
If the manufacturer or retailer doesn’t explicitly state the content of bamboo under the fleece, then assume these are microfibre.
So as you can see it really isn’t the case that one fabric is better than another. Each has their own uses. If an insert can hold 200ml of liquid, then it can hold 200ml of liquid. What it is made from is kind of irrelevant from that perspective.