you can use the clay over and over, you should be able to use it more than 4 times (if you cut it into 4 cubes and 1 cube is good for the whole car, meaning 4 uses). we claybar cars all the time at work and weve had the same bar for over a year and a half and its still perfect. you can just use water and a spray bottle as lubricant and spray water on the claybar too. you just have to make sure everything is well lubricated, or the clay wont want to slide across the surface, it will stick and leave little clumps of clay.