I have never seen any color change. It's white, stayed white even when I tested it on water with vegie oil mixed in it. I wanted to see what it looked like when water was put on it. It just lumped up to absorb the water, so as far as I can say, it works, at least it does for me.
As I have said, I do turn the ball every 20-30 min, and I keep the ball in the bag for 2-3 hours. Left one once 8 hours, I just forgot to get it out and got busy, didn't hurt the ball at all (it was my wife's GameBreaker)and as much as she's an Ebonite freak, if it'd had hurt the ball, she'd let me know !
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az guy aka: R & L Bowlers Pro
rlbowlerspro@cox.net