It is a sickness, even though I'm not a metal worker nor can I stand endless rubbing of the backs of cutters to flatten them, I have a sharpening jones.
Over on SMC there is a thread on Ark stones. I decided to expand it to include JNats. Here is what I published.
While natural stones have been around much longer than synthetic stones
they are not as easy to classify and to understand. The other thread on
the forum about Ark stones sent me to the shop this afternoon to check a
couple of things out. I like natural stones for honing and polishing
and will normally use man made stones to grind. For grinding the most
important thing is speed with less importance for the scratch pattern as
long as it isn't too deep or inconsistent. For honing and polishing
speed is pretty far down the list, what is important is the scratch
pattern. How deep, how steep, and how random the scratches left by the
stone are the three things that determine the quality of the cutting
Synthetic stones are easy, a 5,000 or 10,000 grit stone is, within
reason, pretty much like any other stone of the same grit. So the
sharpening process is easy to figure out, a 1000 grit to grind, a 5000
grit to hone and a 8000/10000 to polish and it makes little never mind
what make of stones you use. Heresy I know, one of the reasons civil
wars are so ugly is because they are fought over such small differences.
With natural stones grit has no meaning. Sometimes you will see a grit
range assigned to a stone but what that is telling you is the stone may
give a finish similar to a synthetic stone of that grit range. The only
real test is to take metal to stone and see what it does.
With Ark stones specific gravity can be a good starting point, the
higher the specific gravity the finer the stone will usually cut. With
JNats hardness can be a clue but so many things can affect the quality
of the finish the only way to know if a stone is a soul mate is to use
it. The reason for that is in the structure of a JNat. A synthetic stone
is made of sized grit particles that break free during the sharpening
process and while they will break down some they remain more or less
square particles. A JNat cutting particles are flake like and while they
do not change much in size in the slurry they do get thinner and
because they are flake like the scratch pattern is smoother.
This is just my opinion with nothing to back it up but one of the
reasons synthetic stones give such a shinny surface is because of their
sharp sided scratches. With JNats some of the most prized stones leave a
Kasumi or cloudy surface. In fact my favorite JNat finishing stone
isn't very hard but it makes slurry very easily and leaves a beautiful
Kasumi finish and edges that last a long time.