Thread: Belgian, Japanese...other weird, slurrific hones?

Originally Posted by avatar1999

I have to agree with Sham on this one. Slurry is the removal of particles from the stone. If the other stones didn't produce a slurry, the stone would never wear out and never need to be re-lapped.

It may not make a noticeable slurry, or one that is beneficial, but I think technically it does produce one IMO.

Oh, sure. I didn't mean that non-slurry stones like black or translucent Arks were like Kryptonite and could never be abraded (though they can certainly seem that way when you're trying to lap them ) I just meant that to my knowledge – and perhaps I'm wrong about this – the result of such abrasion would not be a garnet-rich abrasive milk capable of accelerating or otherwise significantly altering the honing process, which is what people generally mean by slurry. In other words, you could, with effort, work up a milky substance on the surface of any natural stone (or any artificial stone so long as it wasn't a metal plate like a DMT) but it wouldn't necessary change the cutting action.

But maybe I'm wrong about this? Has anyone here used a slurry to speed up a hard ark, for example, and succeeded? I'd be curious.

Originally Posted by northpaw

Thanks, guys.

I thought Belgian hones were similar to Japanese hones, in that the garnets would break down in the slurry, but now I understand that using slurry with them simply speeds up the honing process - as it does with other natural hones.

Guess those Japanese stones are in a class of their own as far as how they work.

This is all incorrect. Thuringian hones, like the Escher, and also the Japanese natural hones, have silica grains for abrasive particles.
The Belgian hones use spessartine garnets, which is some form of faceted crystals. Spessartine Garnets show no cleavage.
Very roughly put, silica is quartz in non crystalline form and it does fall apart in smaller particles when submit to pressure.

Silica based hones rely on the fineness of the particles for a great edge.

Spessartine garnet bases hones (as for as I know only Coticule and BBW) rely on particles that cut a wide yet very shallow pattern.


a Spessartine Garnet Crystal


Silica particles.

Originally Posted by avatar1999

I have to agree with Sham on this one. Slurry is the removal of particles from the stone. If the other stones didn't produce a slurry, the stone would never wear out and never need to be re-lapped.

It may not make a noticeable slurry, or one that is beneficial, but I think technically it does produce one IMO.

The arkansas and similar hones don't wear by the removal of particles, at least not as a primary mechanism. The particles themselves gradually wear down. As with the Nakayama this is important for them to reach their potential. Arkansas stones produce better edges as they break in and the rounded tops of the abrasives become flatter and even slower-cutting. They may occasionally popout of the binder but this is a fairly unusual occurrence.

This is also why arkansas stones are such a cast-iron b*tch to lap.

Originally Posted by mparker762

The arkansas and similar hones don't wear by the removal of particles, at least not as a primary mechanism. The particles themselves gradually wear down. As with the Nakayama this is important for them to reach their potential. Arkansas stones produce better edges as they break in and the rounded tops of the abrasives become flatter and even slower-cutting. They may occasionally popout of the binder but this is a fairly unusual occurrence.

This is also why arkansas stones are such a cast-iron b*tch to lap.

this is basically correct.Arkansas stones will mostly(particules) wear down.Not all of them they will some come off too. Actually new arkansas stones has this problem more then old ones.
it is novaculite mostly contain silicon dioxide.
This is the original question was asked

As far as I've heard, Belgians and Japanese natural hones are the only two hones that make magical slurry (i.e. the slurry contains round garnets, or it's wonderfully frangible, etc.). Do any other hones have special slurry, or just those two?

The idea in this question was.do they make slurry or not. Not how they make slurry. Answer is they all do.

Actually, that wasn't quite what I meant. Sorry if I wasn't clear.

I have a few natural stones: Arkansas translucent, C12k, Dragon's Tongue, and a borrowed Thuringian. I know that with some effort a slurry can be made on all of them, and my understanding was that it typically makes the honing action faster, coarser, or some combination of the two.

My understanding of the Japanese hones was that they are so special because the particles in their slurry break down so finely, producing a better and better edge as you hone. This is why I thought that it's recommended to use a rubbing stone and make a slurry before you start, while this is not the "standard" way of using other natural hones (that I know of).

To put it another way: if you start with a Japanese stone and use it with just water, it might give you the equivalent of 20,000 grit, while using it with a slurry will eventually produce the equivalent of a higher grit. My question was whether or not other hones are known to work this way.

For example, why wouldn't the silica in the slurry from an Escher also progressively break down and make a better edge than just using it with water, considering the below info?

Originally Posted by Bart

Thuringian hones, like the Escher, and also the Japanese natural hones, have silica grains for abrasive particles.
Very roughly put, silica is quartz in non crystalline form and it does fall apart in smaller particles when submit to pressure.
Silica based hones rely on the fineness of the particles for a great edge.

Originally Posted by northpaw

Actually, that wasn't quite what I meant. Sorry if I wasn't clear.

I have a few natural stones: Arkansas translucent, C12k, Dragon's Tongue, and a borrowed Thuringian. I know that with some effort a slurry can be made on all of them, and my understanding was that it typically makes the honing action faster, coarser, or some combination of the two.

My understanding of the Japanese hones was that they are so special because the particles in their slurry break down so finely, producing a better and better edge as you hone. This is why I thought that it's recommended to use a rubbing stone and make a slurry before you start, while this is not the "standard" way of using other natural hones (that I know of).

To put it another way: if you start with a Japanese stone and use it with just water, it might give you the equivalent of 20,000 grit, while using it with a slurry will eventually produce the equivalent of a higher grit. My question was whether or not other hones are known to work this way.

For example, why wouldn't the silica in the slurry from an Escher also progressively break down and make a better edge than just using it with water, considering the below info?

I'm no expert, and other than the Coticule, which is famous for slurry, and basically the C12k, which when you produce a slurry will cut your work in half I.E. 100 lapps without, 50 lapps with, and I have a Nakayama and a slurry stone for it, but I don't use it.
I like it without, and it's top notch finisher. The slurry produced on a Nakayama is almost non existent, I guess it would speed it up, but I rarely use, and savor every moment when I'm using it.....

Even on one of my Escher's it say's, ( it still has the directions) When you draw your blade from heel to toe, A fine slime will be produced to "Enlargen the cutting propeties of the hone". I can try to take a pic if anyone is interested.

My thinking is this, and again, I'm not an expert. If a hone is 8000 grit, say like a Coticule, When you raise a slurry, it's not going to be a 4000 grit. That's impossible. The garnet's will not change. You'll just have more of them to assist in the honing, or speed it up. But the overall grit of your hone stays the same. Now, you can use a Coticule Slurry stone on a BBW.
That's interesting....

Slurries just increase speed, not the size of the grit. IMHO.

Originally Posted by zib

My thinking is this, and again, I'm not an expert. If a hone is 8000 grit, say like a Coticule, When you raise a slurry, it's not going to be a 4000 grit. That's impossible. The garnet's will not change. You'll just have more of them to assist in the honing, or speed it up. But the overall grit of your hone stays the same. Now, you can use a Coticule Slurry stone on a BBW.
That's interesting....

Slurries just increase speed, not the size of the grit. IMHO.

a given grit, in the right matrix/binder, can cut finer that the grit alone in a slurry.
spyderco hones (the UltraFine if i recall correctly) are said to be a rather large grit, but in a particular matrix that lets it cut more shallow/fine.

Originally Posted by zib

Slurries just increase speed, not the size of the grit. IMHO.

This much is certainly true, as to state otherwise would be a physical impossibility.
However, use of a slurry with a coticule definately does reduce the sharpness of the edge (Probably why it was quite confusingly said to act like a lower grit hone). This is thought to be due to the edge colliding head on with the garnets in the slurry.
The reverse seems to be true for Japanese naturals. Use of a slurry with these stones seems to have the ability to impart a sharper edge, but I don't know a lot about these hones.

So while the use of slurry does generally increase speed it also has an effect on the sharpness of the edge which can be attained with that particular hone.

No matter the slurry made whether garnets or alumina there is a self limiting process because you keep adding water which dilutes the particles and as you hone they wash off (unless you have some device so they keep building up on the stone) and new coarser stuff is produced and the grinding and wash away process continues.