Sanitary Pants Materials
Two disposable menstrual pants can look identical and behave completely differently, because the difference sits in the layer stack. This page explains what each layer does, which material choices are open to a buyer, and how to write them into a specification a factory can actually quote against.
The layer stack
Every disposable sanitary pant is a stack of five functional layers plus adhesives. Specify them top to bottom, because a change in one layer usually forces a change in the next.
| Layer | Job | If it is wrong |
|---|---|---|
| Topsheet | Pass liquid through, feel dry | Wet feeling, skin complaints |
| ADL | Spread a sudden surge before the core takes it | Side leakage on heavy flow |
| Core | Store liquid under pressure | Leaks when sitting or lying down |
| Backsheet | Block liquid, optionally breathe | Strike-through, or condensation and odour |
| Cuffs | Form a physical barrier at the leg | Leaks at the leg opening regardless of core |
Absorbent core
The core is fluff pulp and superabsorbent polymer (SAP), usually with a tissue wrap. The two components trade off against each other:
- More pulp — absorbs fast, feels thicker, can release liquid back under body weight.
- More SAP — holds more per gram and holds it under pressure, but absorbs more slowly, so a surge can run off before it is taken up.
That is why the ADL exists, and why a core is never specified by absorbency alone. Ask a supplier for three numbers together: core weight, SAP percentage, and the absorption and rewet results for that exact construction. A quote with only an absorbency figure cannot be compared with anything.
The most useful question you can ask: "what is the core weight in grams and the SAP ratio, and what were the rewet results?" A supplier who answers precisely is quoting a product. One who answers "high absorbency" is quoting a brochure.
Topsheet
The topsheet is a hydrophilic nonwoven or a perforated film. Three practical options:
- Spunbond nonwoven — soft, cheap, widely used. Slower to let liquid through than a perforated film.
- Through-air bonded nonwoven — bulkier and softer, better for premium positioning and for postpartum products where skin contact matters.
- Perforated film — fastest liquid transfer and a very dry surface, but less soft and noisier.
Ask for the fabric weight (gsm) and the supplier name. Fabric weight is the usual place a cost reduction is hidden: the product still looks the same and feels thinner in use.
Backsheet
The backsheet is either a PE film or a film laminated to a nonwoven. The choice is a trade-off, not a quality ranking:
| Option | Strength | Weakness |
|---|---|---|
| Standard PE film | Reliable liquid block, lowest cost | No breathability; condensation and odour |
| Breathable PE film | Lets vapour escape, cooler in use | Higher cost; breathability must not compromise the block |
| Cloth-like nonwoven laminate | Quiet, textile hand-feel, premium perception | Highest cost, and bulkier to pack |
Breathability and odour are the same trade-off, and both are decided here. A film that blocks liquid completely also traps humidity, and a warm, damp microclimate is what turns an ordinary wear interval into a noticeable smell. The material side of each is set out in breathable menstrual pants and odor control in menstrual pants.
If a supplier claims breathability, ask for the moisture vapour transmission rate and the hydrostatic head together. One without the other describes half a material.
Cuffs and waistband
Most leaks reported as "the core did not hold enough" are actually leg-cuff failures. Ask about:
- Cuff material — hydrophobic nonwoven, and its weight.
- Elastic strands — one or two, and the elongation used.
- Cuff height — a taller cuff contains more, but can bunch.
- Waistband — elastic thread count and stretch recovery after repeated extension.
Stretch recovery is the number worth testing. A waistband that stretches well but does not recover will not keep a loaded garment in place.
Writing the specification
A specification a factory can quote against has four parts: the layer stack with material and weight, the performance targets with test methods, the size grading, and the packaging. If any part is missing, the supplier fills the gap with whatever is already on their line.
Put the same document into the purchase order and reference it in the quality agreement. The inspection side is covered in the acceptance criteria, and the product-level view in disposable menstrual pants.
The layer most briefs miss
The stack table above lists an ADL between the topsheet and the core, and it is the layer buyers most often forget to specify. The acquisition distribution layer spreads a sudden arrival of liquid across the core so the core can take it up, instead of the liquid running to the sides. It adds no capacity; it buys time.
Whether you need one depends on the arrival rate rather than the total volume:
- Overnight and heavy flow — yes. A single gush arrives faster than a high-SAP core absorbs, and the overflow travels sideways along the cuff. The constructions are compared in overnight period pants and heavy-flow menstrual pants.
- Postpartum — usually yes, for the same reason, and because the product is worn longer between changes.
- Light daytime and teen products — often not. A thinner stack without an ADL is cheaper and the arrival rate does not justify it.
If it is specified, specify it properly: fibre type, weight in gsm, and the pattern or embossing that does the spreading. An ADL written only as "with ADL" is not a specification, because the cheapest version of it is a light spunbond that spreads very little.
Cut a sample open. With dry scissors, split a sample along its length and separate the layers. A real ADL is a distinct sheet between the topsheet and the core wrap, usually with a visible pattern. If the topsheet sits straight on the fluff there is no ADL, whatever the quotation says. Do this once on the approved sample and keep the cut sample with the signed paperwork.
Detecting a substituted material
A substituted material is the quietest failure in this category, because the product still looks right. A nonwoven a few grams lighter, a film a couple of microns thinner, or a different pulp grade changes the cost and surfaces months later as a complaint. You cannot see it on arrival, and the supplier may not regard it as a change at all.
Three checks catch most of it and none needs a laboratory:
| Check | How | What it catches |
|---|---|---|
| Piece weight | Ten pieces on a 0.01 g scale, against the approved sample | Lighter core, thinner film, less SAP |
| Calliper and dimensions | Thickness at three points, length and width on a flat sample | Thinner stack, size grading drift |
| Layer identification | Cut one open and compare layer count, ADL and cuff material | Removed ADL, changed cuff nonwoven |
Record those numbers on the approved sealed sample when you sign it off: weight per piece, thickness, length and width. That record is the entire check. Without a number written down at approval, "it feels lighter" is an opinion and cannot be enforced.
Then put the material names and weights in the purchase order as well as the specification. The purchase order is the document you can act on; the specification is the one that gets filed. The inspection side of the same problem is in sanitary pants quality control.
Skin contact: what skin friendly has to be made of
Skin-friendliness is a claim, not a material. Three things actually drive it: what the topsheet is made of and how it is finished, what is left in it from manufacture, and how much moisture is held against the skin.
- Topsheet construction. Spunbond, SMS or a hot-air-through carded nonwoven, each with a stated basis weight. Carded topsheets feel softer and more cloth-like; apertured topsheets move fluid faster but feel more synthetic.
- pH of the finished product. Ask for the aqueous-extract pH on a production sample rather than the claim. Skin sits mildly acidic, and a product far outside that band is where irritation complaints start.
- Residuals and additives. Fragrance and printed dye on the topsheet are the two most common irritant sources. Fluorescent brightening agents and residual formaldehyde belong on the same list of things to require a report for.
- Occlusion. A breathable backsheet lowers humidity. If you intend to claim breathability, specify the moisture vapour transmission rate in grams per square metre per 24 hours rather than the word breathable.
Hypoallergenic and dermatologically tested are not regulated terms in most markets. They only mean something when a test report is attached: ask for the laboratory, the protocol (an in-vitro skin irritation test or a recognised patch-test protocol), the panel size and the date. A supplier who cannot produce the report has made no claim you can use.
Make it contractual: list the topsheet type, basis weight, pH range, the prohibited additives and the required test reports in the specification, then verify against pre-shipment samples. The inspection side of the same problem is in sanitary pants quality control.
Frequently asked questions
- Does a heavier core always mean better absorbency?
No. A heavier pulp core absorbs quickly but can release liquid under pressure. SAP content and the presence of an ADL matter as much as total weight.
- What is an ADL and do I need one?
An acquisition distribution layer spreads a sudden surge so the core can absorb it. Overnight and heavy-flow products usually need one; light daytime products often do not.
- Can I specify the nonwoven supplier?
You can ask, and for a premium product you should. Confirm whether the named material is used in mass production or only in the sample.
- Is a breathable backsheet worth the cost?
It depends on wear time and climate. For long-wear and hot markets the comfort difference is real; for short daytime wear the benefit is smaller than the cost.
Latest industry notes
Short write-ups from our sourcing team on compliance, trade events and material changes that affect purchase orders.
- Trade Shows & Sourcing EventsWhat to Bring to a Supplier Meeting So the Follow-Up Moves2026-11-01
- Materials & QualityAbsorbency and Rewet Testing for Menstrual Pants: What to Request2026-10-15
- Materials & QualityDisposable Menstrual Pants Quality Control: A Buyer Checklist2026-10-15
Specify materials with confidence
Send the layer stack you need, or the performance target and the market. A material-level brief gets a comparable quotation instead of a generic price per piece.