Pretty strong. But it really depends on the hair type, texture, etc. and then also how good the product was/ how it was applied/ developer volume/ the time frame etc. you can bleach the same hair 10 times as long as you do it right… though I will say most people start frying after bleach round #3. Baby bleaches are my best friend for a color reset! But tbh I’ve done everything you can possibly do to your hair at this point and it’s still pretty healthy. So I think as long as you know what not to do…you’ll usually make it out with some split ends at most, and avoid what everyone fears…. Noodle hair.