do you keep your lips moist or do you not put anything on them? because when i kept them moist with the un-petroleum jelly or anything else, they never got tough. they were always soft and then fell of very easily. and when i first started my experiment the skin stayed on for a little over a week. but if you arent putting anything on them then yes they will get tough. mine used to crust up like a scab when i put nothing on them. and i think most peoples do.