I never tried it, and I'm not sure I want to. My present plan of action is to refill them with the same or a similar juice till they die, then toss them. It sounds like a lot of trouble to clean them out. However, if I'm going to be sampling lots of flavors, I'm going to be buying lots of cartos. So maybe I should rethink that. Anyway, I amassed a bunch of info from people when this topic last came up, and I could PM it to you, as I have done for others. It takes 2 messages, it's so long. Some people seem to have good luck with a machine that cleans jewelry. That sounds efficient and less trouble than some other methods, though it means buying another piece of machinery. Anyway, let me know if you want everyone's various methods of cleaning cartos.