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Why a thick pad doesn't necessarily absorb more
Thickness is something you feel in your hand. Absorption is measured — and the two have little to do with each other.
What absorbs in a modern pad is not the bulk of fluff: it is the superabsorbent polymer, a few grams of granules able to hold many times their own weight in liquid. A thin pad with enough of it absorbs more than a thick pad padded out with cellulose that has almost none.
Three measurements tell the truth, and laboratories apply them to standard methods. Free swell capacity first: what the product takes up with nothing pressing on it. Then absorption under load, which is to say while you are sitting on it. And finally rewet: how much liquid comes back up towards the skin under pressure. That last figure is what decides whether you feel dry.
Absorption under load is always lower than free capacity. That is exactly why a pad that drinks well lying flat on a table can give way once you sit on it. In the hygiene industry, absorption under load is expected to be in the range of eighteen to thirty grams per gram.
Another trap is the demonstration done with plain water. The salts in body fluids sharply reduce what the polymer can hold: a test with water gives far better figures than a test with saline, which is closer to reality. A video of someone pouring a glass of water onto a pad therefore proves nothing.
What to look at when buying: length, two hundred and forty millimetres for the day and two hundred and ninety for the night; side barriers; what the layer against the skin is made of, and whether it breathes; and finally the number of pieces in the pack. And ask whether the brand can show its test reports: a certified brand has them.
