Thread: Rockwell hardness and honing

Discussion topic ... not a lesson from me.

The recent thread "Swaty Stones for finishing" got me
pondering about why we want to use a light touch for honing
and how it is possible for such a variety of hones from
Arkansas to Waterstones all qualify as razor hones.

In the method for measuring hardness a hard object
either a hardened ball, or a tungsten carbide or diamond
probe is pressed into the object being measured. The
amount of pressure used can be large (150 kilogram) and the
resulting depth of penetration of an indenter is measured.

Hardness

For finish honing we want as shallow an indent or scratch as
possible so the multitude of particles that result from a
fine grit combine with a light touch to produce uniform and
shallow abrasions.

Bevel setting is slightly different. We want more aggressive
abrasion so the sharp bits need to be further apart and
bigger to generate larger cuts. Between bevel setting
and finish honing the key is to eliminate the furrows from
the previous hone and maintain the geometry.

A slurry is interesting in that the grit in the slurry tumbles and
generates local very high pressure zones. Pasted strops are the
reverse of slurry in that they do not present their grit
with much authority and thus tend to polish more.

So the key point is that a light touch no mater what the hone
will generate much smaller abrasions and this consistent light
touch is critical for a final finish no mater what hone is used.

All resulting in a strop ready edge.

Discuss, thoughts...