Nut Trouble,To Graphite or not to graphite ?

[Mr Scary]

I have a question about non locking traditional bone type nuts. I have heard from several people if you lube the string slots in the nut your guitar will stay in tune better. That does not make sense to me because if the string can slip and slide through the nut then the next place it will pull is the tuner unless you have locking tuners. So how does graphite or any other lubricant help ? I am not having any trouble with tuning or staying in but students have asked me this question and I dont no exactly what to tell them.:confuse:
Thanks

[Slight Return]

Lubricating the slots in the nut with graphite prevents hitching in the nut; that's about it. Hitching in the nut will cause string "pinging," and it will similarly tend to pinch strings and cause them to go out of tune. Basically, all you're doing when you put graphite in the slots is lubricating it so that the string will not get caught in the slot.