Cotton, bamboo and plant-based fibres in diapers and wipes

“Made with cotton.” “Bamboo soft.” “Plant-based.” Diaper and wipe packaging has gone green, and it’s natural to assume that fibres from plants must be gentler than fibres from a refinery. The truth is more interesting. A disposable diaper is a stack of specialized layers, plant fibres fit into only some of them, and the things that decide whether your baby gets a rash have surprisingly little to do with where the fibre came from.

The four layers of a disposable diaper

Absorbent hygiene products, from baby diapers to adult incontinence pads, share the same basic build. A 2023 review of these products describes four layers:

• The topsheet, the soft, permeable surface against the skin. It’s typically a nonwoven fabric (fibres bonded into a sheet rather than woven) made of polypropylene or polyethylene fibres, designed to let urine pass through quickly rather than hold it.
• The acquisition layer, sometimes called a secondary topsheet, made of modified cellulose and polyester. Its job is to move liquid away from the skin and spread it into the core.
• The absorbent core: superabsorbent polymer blended with cellulose, which is wood pulp fluff. This is where the urine ends up.
• The backsheet, a waterproof polyethylene film, often laminated to a soft nonwoven so the outside feels like cloth. Many are “breathable”, meaning the film lets water vapour out while keeping liquid in.

Add elastics, fastening tapes, adhesives and sometimes a lotion on the topsheet, and that’s a diaper.

The part that does the real work: superabsorbent polymer

The core is where plant fibre and chemistry meet. Cellulose fluff soaks up liquid quickly but gives it back under pressure, which is why old-style diapers felt soggy. Superabsorbent polymer, usually sodium polyacrylate, absorbs many times its weight in urine and turns it into a gel that stays put when your baby sits on it.

That matters for skin. A review of more than a hundred studies on neonatal skin care concluded that super-absorbent diapers reduce moisture at skin level and reduce diaper rash. A safety-assessment paper that measured how much liquid comes back to the skin surface when a wet diaper is pressed (the “rewet” fraction) put it at roughly 0.3% to 0.7% of what went in. The same paper found that when a topsheet carries a lotion, only about 3% to 4% of it transfers to skin.

So when a package says “plant-based core” or “made with wood pulp”, remember that every disposable core is mostly wood pulp already, and that the polymer is the ingredient keeping the skin dry.

Where cotton and other plant fibres actually go

When a diaper advertises cotton, bamboo or “plant-based” materials, it’s usually talking about one of three things:

• Fibres blended into the topsheet, so the surface that touches skin contains some cotton or viscose alongside the usual polypropylene.
• The outer cover, where a cotton-like nonwoven replaces a plastic-feel film.
• Plant-derived versions of the usual plastics, such as polyethylene made from sugar cane rather than petroleum. Chemically it’s the same plastic; only the raw material differs.

Wipes are simpler: the cloth (the basesheet) is a nonwoven usually made from wood pulp, polyester, polypropylene or a mix, and sometimes cotton or viscose. A wipe that says “plant-based fibres” is typically one where a plant fibre has replaced some of the polyester.

“Bamboo” usually means viscose

Bamboo is the marketing champion of the category, and it deserves a closer look. Bamboo stems can’t be spun into soft fabric mechanically the way cotton or flax can. Instead, the plant is dissolved in chemicals to extract its cellulose, which is then pushed through spinnerets into fibre. The result is viscose, also called rayon, the same manufactured fibre that can be made from any tree.

Canada’s Competition Bureau has issued guidance on this under the Textile Labelling Act: “bamboo” on its own isn’t an acceptable fibre name for these products. They have to be labelled “viscose from bamboo”, “rayon from bamboo” or a similar process-specific name, because the finished material is a manufactured fibre, not the plant.

None of this makes viscose bad. It’s soft, absorbent and comfortable. It just isn’t what the word “bamboo” makes people picture.

What plant fibres change for skin, and what they don’t

Here’s the fair version of the case for cotton and viscose against skin: they’re soft, they absorb a little moisture into the fibre itself, and many parents find them more comfortable on a baby. Softness reduces friction, and friction on wet skin is one of the ingredients of diaper rash. That’s a real, if modest, plus.

What they don’t change:

• Wetness. Rash is driven by how long skin stays wet and how alkaline it gets from urine and stool. That’s decided by the core, the acquisition layer and how often you change the diaper, not by the topsheet fibre.
• Breathability. In a series of double-blind trials, infants in highly breathable diapers had 38% to 50% less severe diaper rash, including confirmed yeast infections, than infants in standard non-breathable ones, and the more breathable the diaper, the lower the rash rate. Breathability comes from the backsheet film, not the fibre.
• Allergy. Cotton and viscose are rarely allergens. But neither is polypropylene. The things in a diaper that can cause allergic reactions are fragrance, lotions, dyes and adhesives, and a plant-based diaper can contain all of them. Check for “fragrance-free” separately.
• Fit. Leg cuffs, waistband and sizing decide leaks and chafing more than material does.

And a word on cloth. Cotton cloth diapers are the original plant-based option, and they’re a fine choice for many families. But dermatology references note that diaper rash was historically far more common with cloth than with modern disposables, because cloth holds urine against the skin. If you use cloth, change often and consider a liner.

How to read a plant-based label

• Look for where the plant fibre actually is. “Cotton-enhanced topsheet” is a specific claim; “made with plant-based materials” could mean almost anything.
• Treat “bamboo” as “viscose” and judge it on softness, not on healing powers.
• Check the things that matter more: fragrance-free, lotion-free if your baby has reacted before, a breathable backsheet, and a size that fits.
• Don’t pay extra expecting less rash. The evidence for that goes to dryness and breathability, which plant-based and conventional diapers can both deliver.

You can compare fragrance-free diapers, wipes and creams in our baby care listings.

Plant fibres in a diaper are mostly a comfort and environmental choice, and both are legitimate reasons to buy them. Just don’t let the leaf on the package do your thinking about rash: keep the skin dry, change promptly, skip fragrance, and if a rash keeps coming back whatever you use, ask your doctor or pharmacist to take a look.