Well not exactly. I'd imagine that the wet surface will always have lower gripping ability. You want to know if the wrinkled fingers have better grip on a wet

Well not exactly. I'd imagine that the wet surface will always have lower gripping ability. You want to know if the wrinkled fingers have better grip on a wet surface than unwrinkled fingers. You could wet the fingers and immediately test the grip (before wrinkles form), and then soak them in water until they wrinkle and do it again.