HOW DO YOU KNOW WHEN YOUR BALL IS WORN?
New squash balls have a matte, rough appearance. Your ball will wear out at a different rate depending on your court, your strings and how you hit it. Once you can see a lot of marks or scratches on your ball, or when it starts looking shiny, it's time to change it. You can still use it, but it will be very slippy. It will slip on the floor or walls and end up splitting.
Change it before that happens!