Hopefully someone that knows more about it can give some more info on it. All I know is it is supposed to remove contaminates that have imbedded themselves in the paint. It doesn't seem to be abrasive, using the spray detailer as lube for it makes it just glide across the paint with very little resistance at all.
At first I didn't think it was really doing anything but when I wiped the first section dry it looked like I'd just spent the day polishing and waxing it. The paint at that point felt smooth as glass when I'd drag my hand across the finish.
The clay was whitish so as you go you are supposed to turn it and kneed it around to keep the part that is against the paint as clean as possible. Somehow something about it just grabs the stuff that is stuck in the paint, without taking off the paint. I did notice a bit of color on the clay when I used it on an old non-clearcoated finish, but not much.
It goes very fast since it glides so easily and you can just slide your other hand around feeling for rough areas as you go to make sure you got everything. I'm not sure exactly how long it took as I wound up doing 3 cars with it the same evening
I've never used it on a brand new car but the finish after using it was better and smoother than when the car was new. I've read posts from people that recommend it for new ones.
-Trevor