Absorbent Core for Diapers — Raw Material Guide for Manufacturers 2026
The absorbent core is the heart of every diaper. Topsheet, backsheet, and tapes get attention — but it is the absorbent core that determines how much fluid the diaper can hold, how dry the surface stays after wetting, and how long the diaper performs before leaking. For manufacturers, the absorbent core is also the single largest raw material cost line — typically 35–45% of total bill of materials.
This guide covers every component of a modern diaper absorbent core: fluff pulp, super absorbent polymer (SAP), acquisition and distribution layer (ADL), and the topsheet that feeds it. Specifications, typical loading ratios, performance optimisation, and sourcing from Favourite Fab in India.
Absorbent Core Architecture
A modern baby or adult diaper core has four functional layers:
- Topsheet: Skin-contact layer — hydrophilic spunbond, allows fluid through quickly, stays dry on top
- ADL (Acquisition & Distribution Layer): Below topsheet — receives the fluid surge and spreads it laterally before passing to the absorbent layer
- Absorbent layer: Mix of fluff pulp and SAP powder — captures and locks fluid
- Backsheet: Bottom barrier — prevents leak-through
The fluid path: skin → topsheet → ADL → absorbent layer → locked in SAP gel.
Component 1: Fluff Pulp
Fluff pulp is comminuted (defibrated) bleached softwood kraft pulp. It provides bulk, capillary action, and rapid acquisition capacity in the core. Unlike SAP, fluff releases fluid under pressure — but it acquires fluid 5–10× faster than SAP alone, which is why every diaper core uses both materials together.
Specifications
- Density in core: 0.10–0.20 g/cm³ (compressed)
- Loading rate: 5–15 g per baby diaper, 15–40 g per adult diaper
- Source species: Southern pine (US), Scandinavian softwood (Europe), eucalyptus (premium soft cores)
- HSN code: 4703 (chemical wood pulp)
Fluff pulp is sourced as compressed rolls or bales. Diaper machines defibrate the pulp on-line via hammermills before laying down the air-formed pad.
Component 2: SAP Powder (Super Absorbent Polymer)
SAP — chemically sodium polyacrylate — is a cross-linked polymer that swells into a gel when contacted with water-based fluid. It absorbs 30–60 times its own weight under pressure (AUL — Absorbency Under Load) and retains the fluid even when squeezed.
Grade selection by application
| Grade | Free Swell (g/g) | AUL @ 0.3 psi | Application |
|---|---|---|---|
| Baby diaper standard | 45–55 | 28–32 | Mass-market baby diaper |
| Baby diaper premium | 55–60 | 30–35 | Premium / overnight diaper |
| Adult diaper | 50–60 | 25–30 | Adult incontinence — higher gel strength |
| Sanitary pad | 40–50 | Less critical | Faster absorption priority |
Detailed specs: What is SAP powder | Bulk SAP price list
SAP loading optimisation
Modern diaper design has shifted toward higher SAP-to-fluff ratios over the past 15 years. The trend driver: thinner cores, lower transport cost, better consumer perception. Typical core compositions:
- Conventional core (10 years ago): 80% fluff / 20% SAP
- Standard core (today): 50% fluff / 50% SAP
- Thin core / pull-up: 30% fluff / 70% SAP
- Ultra-thin / fluffless: 0% fluff / 100% SAP (held in nonwoven channels)
Higher SAP ratios reduce diaper weight and bulk but require careful core engineering — without enough fluff or channelling, SAP can “gel-block” and reduce acquisition speed.
Component 3: Acquisition & Distribution Layer (ADL)
ADL is a high-loft nonwoven placed between the topsheet and the absorbent layer. Without an ADL, fluid pools at the topsheet causing rewet and leak. With a quality ADL, fluid is acquired in <1 second and spread across the core surface area before passing to SAP.
ADL specifications
- GSM: 25–50 GSM
- Construction: Through-air bonded bicomponent fibre (PE/PET) or resin-bonded carded
- Loft: 0.8–1.5 mm bulk
- Strike-through time: <1 second (first insult)
- Rewet: <0.5 g after three insults of 80 ml
Detailed page: Nonwoven raw material for baby diapers
Component 4: Hydrophilic Topsheet
The topsheet must allow fluid through fast (strike-through) while feeling dry on the skin (rewet resistance). Untreated PP nonwoven repels water — therefore topsheet PP is treated with a permanent hydrophilic finish (silicone-based or surfactant-based).
- Material: PP spunbond, hydrophilic treated
- GSM: 12–18 GSM (baby), 18–22 GSM (adult)
- Strike-through: <3 seconds
- Embossing: 3D pattern available — improves dry feel and reduces rewet
Core Performance Targets — How to Spec a Good Core
For Indian B2B production, target these performance benchmarks:
| Test | Baby Diaper Target | Adult Diaper Target |
|---|---|---|
| Total absorbency | 200–350 ml | 800–1,500 ml |
| Strike-through (1st insult) | <3 seconds | <5 seconds |
| Rewet (after 3 × 80 ml) | <1.0 g | <2.0 g |
| Retention under load | >80% of free swell | >75% of free swell |
Single-Source Supply — Favourite Fab
Favourite Fab supplies all four core components from one facility:
- Hydrophilic spunbond topsheet — 12–22 GSM, ±2% GSM tolerance
- ADL nonwoven — 25–50 GSM, both resin and through-air bonded
- SAP powder — baby and adult grades, 25 kg bags
- SMS / SMMS backsheet nonwoven — 16–25 GSM
The only component not produced in-house is fluff pulp (sourced via partner network from Domtar, Resolute, or local agents). For a complete sourcing plan, see the Diaper Raw Material Supplier India guide.
Also relevant: Setting Up a Diaper Factory — Investment & ROI
Frequently Asked Questions
How much SAP is in one baby diaper?
A standard medium-size baby diaper contains 6–10 g of SAP and 8–12 g of fluff pulp. Premium overnight diapers may use 12–14 g of SAP. Ultra-thin pull-up diapers use 10–13 g of SAP with 2–4 g of fluff or no fluff at all.
What is the difference between SAP for baby and adult diapers?
Adult diaper SAP is engineered for higher gel strength under prolonged load — it must hold fluid for 6–12 hours under body weight without gel-blocking. Baby diaper SAP prioritises speed and free swell capacity for shorter wear cycles.
Can I make a diaper without fluff pulp?
Yes. Fluffless or “zero-pulp” cores hold SAP in nonwoven channels (typically tissue or carded SMS). They are thinner and lighter but require specialised core-forming machinery and carry higher SAP cost per unit.
What is the typical core weight for a size-M baby diaper?
Size M baby diaper total core weight: 16–22 g (8–10 g SAP + 8–12 g fluff). Plus topsheet, ADL, and backsheet, total diaper weight is 28–35 g.
Where can I source SAP powder in India in bulk?
Favourite Fab supplies baby and adult grade SAP in 25 kg bags with MOQ of 500 kg. Larger contracts (5+ MT/month) get tiered pricing. See Where to buy SAP powder in bulk.
Does fluff pulp affect diaper softness?
Indirectly, yes. Higher fluff content gives a softer, more cushioned feel but increases bulk. Lower fluff with higher SAP gives a thinner, harder core with less cushion. Premium diapers balance the two and use a soft topsheet to mask any core stiffness.
Get Core Component Samples
Test your core design with samples of all four layers. Favourite Fab provides 1–5 metre rolls of topsheet, ADL, and backsheet plus 1–5 kg SAP samples for production trials.
- 📞 +91 95288 11566
- ✉️ sale@favouritehub.com
- 🌐 Request samples
Gaurav Garg
I'm Gaurav Garg, CEO of Favourite Fab, a company on a mission to revolutionize the nonwoven industry with sustainable practices. We work hand-in-hand with manufacturers and suppliers who share our commitment to eco-friendly production. With a deep interest in textile innovation, I'm passionate about educating consumers about sustainable material options and their potential to transform the nonwoven landscape.
