I have a special briefcase that I have put compartments in. I store them in a compartment. I am sure that my working area is clean and that when I am finished with them, I put them in a pocket or back in the briefcase. I also never combine using them with the plack ones. I use red. The black rubs off. I did however make the mistake of doing a routine with a friend whos hands were not clean. I just brushed the ball with my dry fingertips untill it was clean. It took some time. Don't use water to clean them, the color will come out. I also try to remove the lint that may collect on them durring the routine. It is not inappropriate to remove a piece of hair or lint that a ball has picked up after it has fallen and then continue.