Thread: What actually is Hardness in natural stones, and how it affects sharpening

When it comes to hardness I've always took it into account but its always been a lesser factor in determining cutting power IMO.

I have two coticules; a la verte and dressante. The Dressante doesn't leave a hint of a mark with the nail test but is a quick cutter and finisher but its a hard coticule. The la verte is very hard but quicker on water and easier to finish, so how that gets explained I haven't a clue.

I would go with the amount of mirror the surface of the natural hone creates when lapped and refined. In order of surface mirror from least to most noticeable of my hones; dressante, BBW, la verte, jnat, which correlates with how easy, sharp and how much of a polished bevel I can get off each hone. I would say the jnat is the sharpest for me but by a milidegree from my coticules, some are easier to get an edge but as with all natural hones its how you use them.

Remember that when we usually refer to hardness its with minerals which are relatively homogeneous substances. Most honing stones are rocks which are combinations of minerals so in one honing stone you may have minerals contained within, that range from a hardness of 4 or 5 up to 8 or nine (for example) and each mineral making up varying percentages of the rock.