Pulp vs SAP Nappies: What's the Actual Difference?

Walk into any supermarket and you'll find shelves full of nappies. But here's what most brands won't tell you: not all nappies are built the same way inside — and the difference matters a lot for your baby's comfort, skin health, and your sanity at 3am.

The two main absorbent core technologies you'll find in disposable nappies today are wood pulp fluff and SAP (Super Absorbent Polymer). Most nappies use some combination of both. A smaller number — including Crikey Bottoms — use SAP only.

What Are Pulp Nappies?

Traditional disposable nappies use a layer of wood pulp fluff (also called cellulose fluff pulp) as their primary absorbent material. This pulp soaks up liquid and holds it — but only to a point.

The problems with pulp:

It's bulky. A thick pulp core creates that padded, saggy nappy look as it absorbs moisture.

It can clump and break down when saturated, reducing effectiveness over time.

It holds moisture close to the skin. Even after absorption, pulp nappies can leave a damp feeling against your baby's bottom — because the liquid is trapped in the pulp layer, not locked away.

Pulp nappies are cheaper to produce, which is why most budget and mid-range nappies still rely on them.

What Are SAP Nappies?

SAP stands for Super Absorbent Polymer. It's a synthetic crystal-based material that can absorb up to 300 times its own weight in liquid and lock it into a gel — keeping it away from your baby's skin.

SAP is what gives premium nappies their performance. It's also what makes them feel dry to the touch even after multiple wees.

The Key Differences Side by Side

Bulk: Pulp nappies are noticeably thicker and bulkier, especially when wet. SAP-core nappies are slimmer and maintain their shape better over time.

Skin dryness: SAP locks moisture into a gel and keeps it away from skin. Pulp holds moisture in a layer that can stay in contact with the skin.

Leak protection: A well-designed SAP core distributes liquid quickly and holds it under pressure, making leaks less likely during active movement.

Nappy rash: Prolonged skin contact with moisture is a leading cause of nappy rash. Drier skin = less rash risk. SAP wins here.

Weight when wet: Pulp nappies become heavy and saggy when saturated. SAP-core nappies stay lighter and trimmer.

Why Crikey Bottoms Uses 100% SAP

At Crikey Bottoms, we don't use any wood pulp in our nappy core. Our formula is 100% SAP — the same technology used in hospital-grade wound dressings and clinical absorbent products.

This means our nappies are slimmer, lighter, and more effective at keeping moisture away from your baby's skin. No bulky padding. No soggy sag. Just a clean, fast-acting absorbent core that does the job properly.

We're not eco nappies. We're not bamboo nappies. We're pulp-free performance nappies made for Australian families who want something better — without compromising on comfort or reliability.

If you're ready to try a nappy that actually keeps your baby dry, check out the Crikey Bottoms range — available in sizes from newborn through to toddler.