If we’re talking about wicking, lower capacity diapers seem to do this better. One of the things I love about my ABU Kiddos is that I can soak them almost to the back. Of course, they leak if I flood them constantly. They still aren’t in the upper tier of high capacity. I wouldn’t choose them for over night, but let’s be fair… overnight is when we can utilize more of a high SAP diaper because of gravity. But, sitting in my home office chair, I prefer the higher end of daytime-grade diapers BECAUSE of their wicking.
Suddenly, that daytime vs overnight difference is cast in stark relief. Maybe it’s more than just capacity?
To me, high SAP zones need to be shaped to be the most effective. Let’s theorize a new diaper design that gets the best of all worlds.
Suppose a two layer pad, one on the bottom (against waterproof plastic) that’s high capacity SAP. Then imagine a second layer where the SAP is concentrated around the periphery of the pad and the rest is much more fluff for fluid transmission. Put a permeable layer between them to encourage structural stability.
Now, you have a diaper with hydrodynamic barriers that will repel fluid into the middle as the SAP there gets saturated. The shape is almost like an inflatable raft filled with fluff. It would help with the “pee out the top” problem. Heck, it would help all around. And the swell pattern… would be like a hug around your crotch.