My mattress/chair protectors, the type with a thin absorbent pad and some PUL-like waterproof backing, seem to have developed a very hydrophobic surface: I can bounce around water drops on the protector around and they aren't really absorbed if no extra pressure is applied. A leak might just dodge the pad and slide off a chair onto the floor. Once the surface does get wet, they absorb fine, but is there any way to make textiles like this less hydrophobic? Save than sewing on a layer of some other non-problematic fabric.

I've washed them with only with very plain / zeolite & fragrance free detergent, without fabric softeners, and dried them in a tumble drier per instructions... this obviously doesn't seem to be working and afaik softeners should only make it worse. Any ideas?