Thread: Nakayama Maruka

Originally Posted by sstomcat

Ok, lot of great discussions here. Just trying to get the terminology straight. A NAgura could be a Mejiro, Tenjou Botan, or Koma. in Japanese circles, could be more kinds.

correct, it is a mine and the different seams are named with different names based on properties. There are ten different seams, but what is left of the mine is Mejiro, Tenjio, Botan, Koma.

A Tomo is a small piece of the same stone is my Beleif? For example if I'm using a Nakayama Kita the tomo nagura is a small Nakayama kita as well? Correct?

can be from any Jnat as long as it is not from Nagura mine.

Scientifically then we are grinding two equally similar surfaces (hard, homogeinity, granularity etc) like diamond on diamond. I therefore would like to assume but would refrain that this too will scratch both surface nagura and hone similarly and may probably raise very very less amount of slurry albeit very fine.

Natural stones do do not obey scientifi classifications, if it was that straight forward we would have very well defined grades of J-Nats except we do not.

Originally Posted by mainaman

Natural stones do do not obey scientific classifications, if it was that straight forward we would have very well defined grades of J-Nats except we do not.

Well, I do believe that the hardness and grit level is based on certain specifics. These specifics even not absolute in a natural occurring stone however form the basic crux of the particular stone. The chemical composition can be declassified if one chooses to but maybe for some reason it has not happened. I however see that numbers are specified in the form of Levels 1-5 or 1-10 for fineness and hardness almost universally. Am I missing something.?

Originally Posted by sstomcat

Well, I do believe that the hardness and grit level is based on certain specifics.

There is no grit level, naturals do not have nice round particles like synthetics do.

These specifics even not absolute in a natural occurring stone however form the basic crux of the particular stone. The chemical composition can be declassified if one chooses to but maybe for some reason it has not happened. I however see that numbers are specified in the form of Levels 1-5 or 1-10 for fineness and hardness almost universally. Am I missing something.?

Knowing the composition does not provide insight of hardness,speed, refinement. It is well known what makes those stones, that is about it. There is a general knowledge of what properties certain mines posses but that is all.

Lots of that has been discussed in various threads on the forum, if you like do a search and read on the subject.

Originally Posted by sstomcat

Well, I do believe that the hardness and grit level is based on certain specifics. These specifics even not absolute in a natural occurring stone however form the basic crux of the particular stone. The chemical composition can be declassified if one chooses to but maybe for some reason it has not happened. I however see that numbers are specified in the form of Levels 1-5 or 1-10 for fineness and hardness almost universally. Am I missing something.?

The chemical composition is in fact known, it's a mineral, based on SiO2 as most of the naturals. As for the shape of the crystals, we know that too. What makes a stone soft or hard is its porosity. Also, all of the Kyoto finishing stones are made out of the exact same mineral. You can take a look at Alex's blog for more information.

Originally Posted by Vasilis

The chemical composition is in fact known, it's a mineral, based on SiO2 as most of the naturals. As for the shape of the crystals, we know that too. What makes a stone soft or hard is its porosity. Also, all of the Kyoto finishing stones are made out of the exact same mineral. You can take a look at Alex's blog for more information.

There you go!, This is what I was ascribing to without knowing the specifics.

Originally Posted by mainaman

There is no grit level, naturals do not have nice round particles like synthetics do.

Knowing the composition does not provide insight of hardness,speed, refinement. It is well known what makes those stones, that is about it. There is a general knowledge of what properties certain mines posses but that is all.

Lots of that has been discussed in various threads on the forum, if you like do a search and read on the subject.

Almost every place that lists Jnats by some very knowledgeable folks list stones with levels for HArdness, Grit/Fineness, particle size cutting speed etc etc. This must be based on something I can only presume, granted we are not talking of round even sizes man made stones.

Originally Posted by JOB15

But dosnt a Nagura break down into finer pieces of slurry than base stone?

No. This is why a lot of us use diamond plates ,because the base stone is finer than any Nagura but not everyone has uber fine base stone which makes opinions vary.

I just honed up a blade.
After the 10k I decided to try the Nakayama with the DMT , its a credit card 1200 mesh.

I use this card to make slurries with the Chosera 1k and 5k, it feels worn and really smooth.
So made a slurry with near enough no pressure.
The slurry which was dark brown on a darkish stone makes it hard to see if its turning darker with metal.
Either way I honed away using 3 dilutions and then 5 laps with water.
The blade is popping hairs easily but I have to wait a few days for growth to test it.

I then decided to hone up another blade seen as I had the Chosera's soaked.
When I came to my Jnat I decided to use the Koma stone which is white or more of a cream colour .
Making a slurry I could see straight away that the slurry was very dark, meaning the DMT had disturbed the stones surface.
So I used a Tomo with pressure to get it smoothed out and not giving up its goods so easily.

This reminded me of when I lap the stone and then smoothen it out with a Nagura, the slurry is very dark because until it gets smoothed out then the slurry is purely the colour of the Nagura.

Maybe I should try to wear the DMT down more?

Originally Posted by sstomcat

Almost every place that lists Jnats by some very knowledgeable folks list stones with levels for HArdness, Grit/Fineness, particle size cutting speed etc etc. This must be based on something I can only presume, granted we are not talking of round even sizes man made stones.

I have always assumed that it works like this:
The seller acquires his stones from Japan or where ever. He/She having knowledge of these stones, tests them and decides , this one is about a 4 and this one is very hard its a definite 5+ and so on.. So I don't think its a scientific process .

Originally Posted by JOB15

I just honed up a blade.
After the 10k I decided to try the Nakayama with the DMT , its a credit card 1200 mesh.

I use this card to make slurries with the Chosera 1k and 5k, it feels worn and really smooth.
So made a slurry with near enough no pressure.
The slurry which was dark brown on a darkish stone makes it hard to see if its turning darker with metal.
Either way I honed away using 3 dilutions and then 5 laps with water.
The blade is popping hairs easily but I have to wait a few days for growth to test it.

I then decided to hone up another blade seen as I had the Chosera's soaked.
When I came to my Jnat I decided to use the Koma stone which is white or more of a cream colour .
Making a slurry I could see straight away that the slurry was very dark, meaning the DMT had disturbed the stones surface.
So I used a Tomo with pressure to get it smoothed out and not giving up its goods so easily.

This reminded me of when I lap the stone and then smoothen it out with a Nagura, the slurry is very dark because until it gets smoothed out then the slurry is purely the colour of the Nagura.

Maybe I should try to wear the DMT down more?

I know more about atoma diamond plates than DMTs, but from what I do know and have seen more than a few times, it's not a good idea to use a DMT or Eze-Lap fine grade plates for slurry making. Both companies explicitly say not to do that, and a lot of people have seen why. It's much easier to have particles dislodged and becoming part of the slurry. And that happens in a faster rate if there is already slurry and you are trying to generate more. Anything finer than the 325 grit is not a safe choice for slurry making, even the 325 can give you problems. And, you also have to wear the plate a little, because in its early stages, a lot of particles are in relatively loose position, and will be removed from the surface of the plate when they have the chance.
As for the atoma plates, they are different, and can be used from 120 to 1200 without any problems, and don't require to be well worn either, although it wouldn't hurt.