We have learned that some NuBall owners have used alcohol as a cleaning agent after using NuBall. Alcohol evaporates very quickly - this is why it feels cold when you get some on your hands. It does the same thing to a ball - it chills a part of the ball almost instantly when applied. This stresses the chemical structure of the coverstock, and does so even more when the ball is warm. At least one customer has had a ball crack when cleaning the ball using alcohol.
NuBall owners are advised to use any cleaning agent made for use on bowling balls - but to avoid use of alcohol at any time!