A measured gush of synthetic urine is released onto a topsheet lying on a stack of standard filter paper, and electrodes time how long the liquid takes to get through, usually a few seconds or less. Repeat insults on the same spot show whether the hydrophilic finish washes off. Fast, stable strike-through with low rewet is the main liquid-handling target for diaper and pad topsheets.
First strike-through is 2.1 seconds but the third insult is 6, so the finish is washing out.
Test aged samples as well as fresh ones, because some hydrophilic finishes migrate or fade in the warehouse.
Also heard as
- strike-through time
- liquid strike-through
- STT
Do not mix it up with
- Rewet: Rewet measures liquid that comes back up through the topsheet after absorption, not how fast it went down.
Related terms
Rewet
Amount of liquid that comes back up through a topsheet under pressure after the pad has absorbed it.
Topsheet
Soft, liquid-permeable nonwoven layer of a diaper or pad that touches the skin.
Wet-out
Line and lab talk for how readily a fabric lets liquid soak in and spread instead of beading on top.
ADL
Acquisition distribution layer: the lofty layer under a diaper topsheet that takes in liquid and spreads it to the core.