In my case, I never used anything other than a hand-sprayed car wash.
Also, my brakes were less than 6 months old and never even got dirty - why would I need a hardcore cleaner? I didn't.
There were less than 5 times that I had the car hand-washed and I am not 100% sure exactly what may have happened then - maybe they used something a bit harsher but I wouldn't think that most car washes would use harsh cleaners?
It is a bummer - However, I am refinishing the calipers with powder coat and will figure out what to do for the rotor hats.
I would not buy this kit again, unless I raced the car regularly (which I don't) and of course I would choose a company with better customer service.