CARE ASSISTANT
ENThree things one number can mean
An absorbency figure looks like a single fact. Behind it sit three different properties, and most packs and most data sheets publish only the first. Knowing which one you are holding is the whole skill.
The first is total absorption capacity: how much liquid the product holds when it is loaded to its ceiling in a laboratory. It is a comparison tool rather than a target, because a product is not worn to its ceiling in use. Read it the way you read the volume of a fuel tank.
The second is the rate of absorption, often shortened to ROA: how quickly the core takes the liquid in. It matters when liquid arrives quickly rather than slowly, and a product with a high ceiling and a slow core can still leak.
The third is rewet, also called moisture return: how much liquid comes back towards the surface when the product is pressed by sitting or by body weight. This is the one the skin experiences. Two products with the same capacity can behave differently here, and a capacity figure will not tell you which is which.
So a lone number answers one of those three questions and leaves the other two open. That is not dishonest in itself; it becomes misleading when it is offered as the summary of a product. When you compare, compare property by property.
One more habit worth keeping: capacity belongs to a size, not to a product name. The same model in 2XL and in 4XL/5XL does not hold the same volume, and a figure quoted without its size cannot be checked.
The test liquid changes everything
Take one product, one method, one laboratory, and run the test twice with two different liquids. You will get two numbers far apart. Neither of them is a lie, and they are not comparable.
Water is the generous liquid. It wets freely, and the superabsorbent polymer used in absorbent cores swells with very little to hold it back. A figure measured in water is the flattering one, and it is the one that looks best on a pack.
A 0.9 % NaCl saline solution, usually called saline, is much closer to what the product meets in use. Its ions limit how far the polymer can swell, so the core holds less. On our products the saline figure comes out at roughly 22 % of the water figure.
That ratio is the thing worth carrying away from this guide. A product rated in water and a product rated in saline can look like different classes of product when they are not. When one sheet shows a figure several times another's, suspect the liquid before you suspect the engineering.
Nateen publishes the saline figure. We chose the lower number deliberately, because it is the one that survives a comparison, and the conditions are named with it: overall absorption capacity, Rothwell method, 0.9 % NaCl saline solution, ISO 11948-1.
If a sheet does not name its liquid, ask. A supplier who measures properly will answer in one line, and that answer costs them nothing. Until it arrives, a water figure and a saline figure are not two grades of the same thing; they cannot be set side by side at all.
The Rothwell method in plain words
ISO 11948-1 is the international standard for testing urine-absorbing aids as whole products, rather than testing a square of core material. The Rothwell method is the handling sequence it describes. In plain words it has four steps.
Weigh the product dry. Immerse it completely in the test liquid and leave it for the time the method sets. Lift it and let it drain for the set drip time. Weigh it again, and the difference between the wet and the dry weight is the total absorption capacity.
The immersion matters because it removes the operator. No one is pouring liquid at a chosen spot at a chosen speed, so the sequence is built for two laboratories to arrive at comparable figures on the same product.
The drain matters for the opposite reason. Without it you would be weighing liquid that is merely sitting on the surface and would run out at the first movement. Those draining minutes are what separates a capacity from a puddle.
What a standard reference cannot tell you on its own is which liquid was in the tank. Sheets quote standards loosely, and a figure obtained in water is never comparable with a figure obtained in saline, however the standard is named beside it. Method and liquid belong on the same line as the number.
One more thing we do, and it works against us on paper: where a laboratory measurement exists for a size, we publish the measurement in place of the calculation, even though it lands three to five per cent below the calculated value. The observed figure is the one we would want to be judged on.
Drop scales and four honest questions
Many packs show a row of drops instead of a volume. It is a friendly idea and a useful one, as long as you know what it is: an in-house scale, set by each brand for its own range.
Nothing converts those scales between brands. The same count of drops on two different ranges was not defined against the same volume, the same liquid or the same wear time. Comparing them produces a conclusion with nothing underneath it.
There is a sharper trap. A large number printed on a pack is not always a count of drops at all, and a prominent twelve may mean twelve hours of intended wear. The icon and the unit are two separate pieces of information, and only one of them is usually printed.
Inside a single range, a drop scale earns its place. It orders products from light to heavy in a way anyone can read standing at a shelf, which is more than a four-digit millilitre figure does for most people.
So when two sheets are in front of you, four questions decide whether they can be compared at all. Ask them in this order, and stop at the first one that comes back without an answer.
If the answers do not come, you have still learned something. A figure with no method behind it is a claim rather than a measurement, and it should not outrank a lower figure that arrives with its conditions attached.
| What the sheet says | How to read it |
|---|---|
| An absorbency figure with no liquid named | Ask which liquid was used. In 0.9 % saline the figure comes out at roughly 22 % of the same product's water figure. |
| "ISO 11948-1" quoted on its own | A standard reference is not a measurement. Ask which test liquid was used and whether the number is a capacity: a water figure is never comparable with a saline one. |
| "Rothwell method, 0.9 % NaCl, ISO 11948-1" | Overall absorption capacity under immersion, comparable with any other saline figure measured the same way. This is what Nateen publishes. |
| A single number offered as the whole picture | Capacity only. It says nothing about how fast the core takes liquid in, or how much comes back towards the skin under pressure. |
| A row of drops, or a numbered drop rating | An in-house scale. Drops do not convert between brands, and a large printed number sometimes means hours of wear rather than drops. |
| "Up to 12 hours" | A usage claim, not a measurement. Wear time depends on the person, on how much arrives at once and on the fit of the size. |
| A calculated value, or a laboratory value | Where a laboratory measurement exists, Nateen publishes it in place of the calculation; it lands 3 to 5 % below the calculated figure. |
| A capacity quoted without its size | Capacity follows size. Measured in Combi X-Ultra Bariatric: 4,300 ml in 2XL, 4,486 ml in 3XL, 4,500 ml in 4XL/5XL. |
What we publish and what we do not
Here is our own disclosure, in full. Beside every Nateen product we publish the overall absorption capacity, measured by the Rothwell method in 0.9 % NaCl saline solution to ISO 11948-1. That is one property, measured one way, in one liquid, and we name all three.
Where a laboratory measurement exists for a size, it replaces the calculated figure. In the Combi X-Ultra Bariatric range the measured values are 4,300 ml in 2XL, 4,486 ml in 3XL and 4,500 ml in 4XL/5XL. The indicative waists for those sizes are 170 to 205 cm in 2XL and 185 to 230 cm in 3XL.
Figures belong to sizes, and the range is wide: briefs with tabs, the Combi range, in XS to 5XL; absorbent underwear and pants, the Flexi range, in S to 3XL; underpads; and shaped pads. There are in-between sizes for young people with disabilities, and premature sizes in the baby range. Every size is given in centimetres and in inches, and bags generally hold ten pieces.
Now what we do not publish yet. The rate of absorption and rewet are not on our sheets today. When they are, the method and the test liquid will be stated beside them exactly as they are stated beside the capacity figure.
We would rather name that gap than let a capacity figure quietly stand in for the other two measures. A sheet that looks complete and is not costs a buyer far more than a sheet with an honest blank in it.
A last word on wear time. Capacity is a laboratory ceiling, not a promise of hours, and what a product does across a day depends on the person, on how much arrives at once, on the fit of the size and on the routine around it. If the size is the open question, the waist measurements on each product page, in centimetres and in inches, are the place to start.
FAQ
Why is one brand's absorbency figure so much higher than another's?
Most often because the two were measured in different liquids. For the same product, the figure obtained in 0.9 % saline comes out at roughly 22 % of the figure obtained in water, so a gap of several times over can sit entirely in the test rather than in the product. Ask both suppliers for the liquid and the method before drawing any conclusion.
What does ISO 11948-1 actually measure?
It measures the whole product rather than a sample of core material: the product is weighed dry, immersed in the test liquid, lifted and allowed to drain, then weighed again. The difference between the two weights is the total absorption capacity. The standard sets that handling, but the number tells you little without the test liquid written next to it, because a water figure and a saline figure are not comparable.
What do the drops on the packaging mean?
They are an in-house scale that each brand sets for its own range, useful for ranking light to heavy on one shelf and meaningless between brands. There is no conversion from one brand's drops to another's. Watch the unit as well, because a large number on a pack sometimes refers to hours of intended wear rather than drops.
- ISO 11948-1 — whole-product testing of urine-absorbing aids
- Nateen product technical sheets
- Nateen laboratory measurements, 2026