Nagura...rules, recommendations

[StonedEdge]

Hi all,

Having recently delved into the world of Jnats, I was wondering about the use of nagura. More specifically:

-What are some rough guidelines in terms of selecting the proper nagura for use on a particular stone?

-Do nagura used to condition a stone's surface post-lapping differ from one used to raise mud for sharpening/polishing?

-Do Jnats that are known to NOT be self-slurrying require a different type of nagura than a softer, muddier stone?
Such as with a hard Uchigumori or Aizu.

Here are the Jnats I have on hand for reference:
-Aizu*
-Aiiwatani HS47
-Ohira Uchigumori HS58

Shinden Kiita Nashiji Lv 4 nagura, which I use with the Aiiwatani

I know some people use Atoma 140 or 400 plates to raise mud, but in terms of using natural nagura, what are some general guidelines on selecting them?

 

[K813zra]

My only rule with natural stones is that I have no rules. I treat every situation as its own. Sometimes I use a hard nagura on a soft stone or a soft nagura on a hard stone. Then other times I reverse that. Sometimes I use a coarser nagura on a finer stone and the other way around too! Honestly though, for stones that self slurry I do not use a nagura at all. Or at least not during the sharpening or polishing process. I might use it as a stone conditioner.

That said, if I am using general guidelines it is still going to depend on the base stone. If I am using an ultra hard base stone that is very fine I am probably going to pick a fine but soft tomo. Something finer than a Mikawa nagura for sure. I treat those a mid grit stones regardless of what others say because that is what they act like imo. Maybe I would use some Takashima Nagura on a Shoubudani Asagi, for example. But if my hone is medium soft to medium hard, say an Oouchi, I might use a harder nagura to kick up slurry directly from the Oouchi itself. Maybe a Ozkuk Asagi nagura...

Again, these are just examples and just what I do. I am sure others do things differently.

 

[StonedEdge]

Thanks for that! It makes sense to me and is a line of thought similar to what I was thinking.

What would be a "hard" nagura to use as a slurry stone on another hard stone? Should I be looking at hardness ratings or stone types?

 

[PalmRoyale]

A Koma nagura is usually hard but you could also use a hard piece of suita.

 

[Marcelo Amaral]

I had some of your concerns some time ago. It is on this thread: http://www.kitchenknifeforums.com/s...d-plates-Vs-Naguras-on-Jnats?highlight=nagura

On knives' bevels, i never had a problem raising a slurr with an atoma so far (Aizu and Shinden included). I also used naguras with great results. On razors, it is customary to use a hard base stone with different naguras in order to further refine the edge.

 

[K813zra]

Thanks for that! It makes sense to me and is a line of thought similar to what I was thinking.

What would be a "hard" nagura to use as a slurry stone on another hard stone? Should I be looking at hardness ratings or stone types?

Eh, I am not as strict as some about being general....That said I would look at a stones rating, if listed, before going by region/mine etc. Or even ask the vendor. I try to generalize as a last resort unless I am taking a gamble on a box of cheap stones or there is no other option.

That said, you seem to be using the scale that Sin uses. You could always just ask him what he has that might match your stone. Or you could try to match up that hardness, generally with another vendors scale. For what it is worth I equate a 8.0 (Aframes) to a 2.5 (JNS) to an HS40 (Watanabe) and that seems to generally get me in the ballpark.

My go to harder nagura is a chunk of Yaginoshima Suita. On the softer side of things I use some Hakka or Takashima if I want to go a bit finer. Beyond that, rather on the coarser side of things I can use some Mikawa, Chu, Tsushima, Aoto or some other Naka-to nagura that I have laying around. I am partial to Tajima in that case.

Sorry if I am kind of just rambling on here. I can only relate this to what I have used, lol.

 

[StonedEdge]

Marcelo Amaral thank you for that link! It goes through many of my questions

Thanks all for the impromptu nagura 101.. Im seeing now that there many ways to use different types of nagura stones combined with different types of base stones for specific needs or reasons. And also that a stone's abrasiveness doesn't dictate it's ability to release slurry or wear the base stone.

K813zra thanks I really appreciate the approximate harmonization of the three scales. It helps puts things in perspective

 

[StonedEdge]

A Koma nagura is usually hard but you could also use a hard piece of suita.

Are suita generally hard stones? Muddy?

 

[Marcelo Amaral]

They are generally not as muddy as red aotos/monzentos, usually in the range of 3-4 in Maksim's scale, although there are softer (than lvl3) and harder (than lvl4).

 

[K813zra]

Marcelo Amaral thank you for that link! It goes through many of my questions



K813zra thanks I really appreciate the approximate harmonization of the three scales. It helps puts things in perspective

No problem. It took me awhile to get there! I find that scale works for me on Awase-to. Naka-to are another story...lol. Meh but you get the idea.