@Paul you might want to read what Marty aka Euclid and I are both saying again, it is actually the same thing, I just think the TNT is more effective then he does :)
The top corner of the hone or the side corner of the hone works very well you just need to be more careful on using it..
If you look at many of the Vintage Eschers and Coticules you can find evidence of the "Corner Drag" left on the hones