Hello Vahmurka, I had the situation with my Blue Diamond chalk that after a couple of hours use the radius of the tipp got smaller. In other words: the thickness of the tipp got less at the edge. Of course this is affected by the way I chalk and also by the fact that the chalk I had was pretty dry. The kamui chalk holds perfectly without giving pressure. Just my experience, that I wanted to tell. So you can see that this tipp shows that special sanding effect as other tipps show, or you can also think: Hey man, riedmich can't use a chalk in a proper way! ;-)