Thread: South African Hones....

Every natural I've seen has grit "balls" in it (if they are that nicely shaped) greater than 10k grit size to begin with, and if anything has grit in the 3-6 micron size that doesn't let go from its natural binder, it can be driven to razor polishing, as long as it wears.

10k size jis is somewhere south of 2 microns.

The only thing I worry about with a natural finisher is whether or not it will hold its grit without releasing it. If it does, I can use it. If it doesn't, I might be able to use it dry or with oil, but i don't like to do that unless the stone is an oil only stone (like an ark).

I'm always curious about natural grit size equivalences, they should almost be given with a full slurry, and disclosed as being hard enough to hold grit or not hard enough. I had a panic when I got my escher initially because I lapped it and it kept getting rid of grit for the first few razors. I could not get an edge the quality I'm used to off of it. It now finally has a nice shiny surface on it, and releases nothing. it's exactly where I want it, and I can get great edges off of it. I doubt the particle size in it is as small as the 12k grit people usually describe, but since it is hard enough to retain its grits, I can get an edge far better and finer than a friable 2 micron synthetic stone would ever give.

So, I'm backing rich's method with natural stones. If it's of any of the types that hold their grit, shave with it (and I'd add to do it with a known keen edge-taking very plain carbon steel razor). That'll tell you all you need to know.

Originally Posted by DaveW

Every natural I've seen has grit "balls" in it (if they are that nicely shaped) greater than 10k grit size to begin with, and if anything has grit in the 3-6 micron size that doesn't let go from its natural binder, it can be driven to razor polishing, as long as it wears.

10k size jis is somewhere south of 2 microns.

The only thing I worry about with a natural finisher is whether or not it will hold its grit without releasing it. If it does, I can use it. If it doesn't, I might be able to use it dry or with oil, but i don't like to do that unless the stone is an oil only stone (like an ark).

I'm always curious about natural grit size equivalences, they should almost be given with a full slurry, and disclosed as being hard enough to hold grit or not hard enough. I had a panic when I got my escher initially because I lapped it and it kept getting rid of grit for the first few razors. I could not get an edge the quality I'm used to off of it. It now finally has a nice shiny surface on it, and releases nothing. it's exactly where I want it, and I can get great edges off of it. I doubt the particle size in it is as small as the 12k grit people usually describe, but since it is hard enough to retain its grits, I can get an edge far better and finer than a friable 2 micron synthetic stone would ever give.

So, I'm backing rich's method with natural stones. If it's of any of the types that hold their grit, shave with it (and I'd add to do it with a known keen edge-taking very plain carbon steel razor). That'll tell you all you need to know.

I don't think it's about not shredding its particles. Even with a really hard stone, if it is not the slurry, it will be the metal particles from your razor or whatever you are honing, that will kill your edge.
Keep it under running water. Also don't hone while someone is vacuum cleaning (you will really see the lines from dust on your edge's polishing) and wait when it rains, that's when the edge looks at its best (I'm kidding now but it really looks cleaner).
The coarseness of a stone surface, when the stone is hard, has something to do with the edge you have while shaving. The shinier the surface of the stone, the better the results. It works for soft stones too.
The grit of the stone has little to do with the edge you have. For coticules, you shave with an 1-5k edge. And feels wonderful. The finest Japanese natural stones are around 8k. And feel awesome. Those flakes from Eschers and C12k'ses have a grit. And without slurry it is very clear. The mountains on its surface of the stone give a pattern on steel's surface, and the sum of the depth from their scratches gives us an estimated grit, always compared to man made stones. The first company I'm thinking about in that case is Naniwa SS or Norton. If they look and feel like an 8k, then it is near 8k. Or 12 or 3k. As simple as that.
Now if you find a stone and think that its grit is "around 10k" doesn't mean many things. But if another 100 people say the same thing, then it has to be around an estimated 10k

Originally Posted by DaveW

Every natural I've seen has grit "balls" in it (if they are that nicely shaped) greater than 10k grit size to begin with, and if anything has grit in the 3-6 micron size that doesn't let go from its natural binder, it can be driven to razor polishing, as long as it wears.

Coticules have spherical grit particles, Jnatas and Thuri/Escher are flakes not even remote resembpance to sphere, they are wide and not very thick.

The only thing I worry about with a natural finisher is whether or not it will hold its grit without releasing it. If it does, I can use it. If it doesn't, I might be able to use it dry or with oil, but i don't like to do that unless the stone is an oil only stone (like an ark).

a quality Jnat will be hard enough to not release slurry on its own. Releasing slurry is not good because it will mix with the worked slurry and mess up the refinement of the bevel. To overcome the hardness fo the stone one uses a softer slurry stone.

Originally Posted by mainaman

a quality Jnat will be hard enough to not release slurry on its own. Releasing slurry is not good because it will mix with the worked slurry and mess up the refinement of the bevel. To overcome the hardness fo the stone one uses a softer slurry stone.

Correct me if I'm (shudder) wrong .... IIRC the old posts about j-nats, from a few years ago, used to say that a nakayma asagi, for example, would gradually auto slurry and the particles would become finer and finer, eventually increasing the effective grit level of the hone ? During that specific session .... to be clear.

I was also under that impression Jimmy. This was given as the reason why the fine Jnat can provide such a seemingly neverending advancement in it's shaving edge. The slurry will break down as you hone into smaller and smaller particles, effectively abrading less and less steel, whilst polishing the edge. I've read the same things about Escher thuris as well,
but not until more recently.

Originally Posted by JimmyHAD

Correct me if I'm (shudder) wrong .... IIRC the old posts about j-nats, from a few years ago, used to say that a nakayma asagi, for example, would gradually auto slurry and the particles would become finer and finer, eventually increasing the effective grit level of the hone ? During that specific session .... to be clear.

When you work the slurry it will break down and refine the edge. If during the process there is a constant release of grit one will never reach the max level of refinement of slurry or edge. A way to get around this to some extent is to decrease the pressure used as the slurry is worked. Another way of doing it is to get a hard base stone that does not autoslurry and use softer slurry stone for the slurry.

Originally Posted by mainaman

When you work the slurry it will break down and refine the edge. If during the process there is a constant release of grit one will never reach the max level of refinement of slurry or edge. A way to get around this to some extent is to decrease the pressure used as the slurry is worked. Another way of doing it is to get a hard base stone that does not autoslurry and use softer slurry stone for the slurry.

Like an Ozuku.....

Is anyone using the purple welsh slate for a finisher still? How does the zulu compare?

Originally Posted by brooksie967

Is anyone using the purple welsh slate for a finisher still? How does the zulu compare?

Are those the hones that were for sale on Ebay, he had 3 different kinds?

Originally Posted by mainaman

Coticules have spherical grit particles, Jnatas and Thuri/Escher are flakes not even remote resembpance to sphere, they are wide and not very thick.

Right, thus the comment "if they are that nicely shaped". It's easier to talk about the size of the particles if the discussion is simplified. The surfaces of most hard stones look like stacked dandruff under a microscope.

a quality Jnat will be hard enough to not release slurry on its own. Releasing slurry is not good because it will mix with the worked slurry and mess up the refinement of the bevel. To overcome the hardness fo the stone one uses a softer slurry stone.

Exactly my point. I'm not aware of a good finish stone that is natural and that does release grit at any appreciable rate. If the particles were 1/10th the size that they are, it wouldn't be such a big deal. But there aren't any that are that small. Most natural stones that are hard and that have uniform reasonably small particles will make a good finisher if they hold their grit. It's hard to draw a line for a certain stone at an equivalent synthetic grit unless some sort of control is used (e.g., a certain exact amount of pressure is used on every single stone). Once you're working with a surface of a stone that is burnished to some extent, you can not necessarily create a finer edge with a stone that has 4 micron particles than one with 6 or 8, it depends on how they work worn in, and how you work with the stone. If the particles are similar shaped, and without regarding hardness, if a slurry is made, the larger particles will likely leave a coarser pattern.

But since we're trying to grade a finish stone based on what it's capable of, it's not really based on particle size within a relative range. Thus, my only real question is how hard is it bound together, how fast does it break in and will it still polish the work done by a slurry once it's broken in. Some super super hard stones still have to be conditioned a little bit from time to time as they are even slow to polish.