avoid like plague.
fills up the rock's pores forever.
plus, it's sticky, so whatever you touch will stick on your hands, that is not only chalk, but also dust, dirt, and so on. I briefly used it many years ago because I thought I was hardcore, but it's horrible, and made even worse by the fact that yes, it's pushed on unsuspecting punters that will use it with no clue where there's no need or reason (like on grit).