there are various electrolysis methods. you can read more information under the electrolysis section of this board. blend method takes longer per each hair, but supposed to have 80-90 percent first time kill for each hair. thermolysis is much faster, but the rate is about 50% to kill each hair the first time around. of course, these are approximate numbers and only apply in the case that the electrolysis is really good at what they do. in addition, this will vary depending on how many of the hair you’re treating is in the anagen phase when you start. if the hair is not killed, the follicle becomes weaker and each time the hair comes back thinner if it’s not killed. but eventually, after 2-4 zaps, the hair should die.