How do I use a jnat

[justino_14]

Hello. Just wondering what I can do on my jnat coming from a 12k Naniwa stone. The jnat I have is not that expensive, it is an Oozuku. I keep seeing the use of several difference nagura stones, which seem quite expensive. If I didn't want to go that route of purchasing nagura stones, can I just use the stone as is? Do I need to make slurry? I've read cutting a piece off the stone to use as a slurry stone, should I do that? I do have a diamond lapping plate, and I have lapped the stone flat. When using the stone, so I go to it from the 8k syn or 12k syn? Just looking for some general guidance, thanks!

 

[Steve56]

Try using it after 8k with thin slurry made with your diamond plate. You should be able to see the edge through the slurry on the first few strokes.

Next, try using the stone with just water only after the 12k. Try 20 light strokes and see if you can tell a difference in the edges.

 

[SliceOfLife]

I use mine like any other hone. Once in awhile I use Tomo slurry. I have all the popular Nagura, but don't use them much. It takes more time to rinse a stone and raise a slurry than it takes me to just do the honing on a synth stone.

Some people like doing the whole nagura progression because they enjoy it and some guys get better edges from it. It's very, very, very rare two different honing methods ending on the same finisher give different results for me, and I'm of the opinion that even when they do it just means I didn't spend enough time on the finisher... so for me, I hone on synths and finish on my jnat (with or without slurry), when I use my jnat.

 

[MO1]

What grit is your lapping plate?
If you have a fine diamond plate, then you can do what alot of guys do, raise a slurry with that as @Steve56 said.
If it's a coarse diamond plate, I would suggest getting a tomo nagura atleast. @Gamma will probably have a bunch on his etsy store "tomonagura"
I have not atleast gotten satisfactory results with slurry from a coarse lapping plate. But it has its use aswell, for speedy mid range work ect.

 

[Toro Blanco]

Steve hit the nail right on the head! Can't get any better advise than that in my opinion.

 

[SliceOfLife]

Yeah, a good tomo is useful and nice to have. I know a lot of guys use Diamond plates to slurry Jnats, but I really don't like the idea of doing that. It will impact the surface of the stone if every time you use it you're basically roughing it up on diamonds. Yes soft stones will lose the scars fast... but not if they're being reapplied every use (assuming you slurry every use).

 

[Atta Aikhjarto]

I think it depends which grit your diamond plate has, how much it is worn out and from which company. An Atoma 1200 which is a bit broken in is the best slurry maker for a jnat you can get for a good reason. A Jnat is usually filled with all sorts of particles and particle clusters which get worn out differently if you use it with an Nagura, which results in an uneven surface structure (different high points which do the cutting). A diamond plate is leveling it out because of its hardness and gives are more even surface than a Nagura which was used for some hours.

 

[SliceOfLife]

The act of honing should level out any peaks and valleys from raising slurry, no? And if the stone is so hard that it doesn't, I don't see a Mikawa nagura stone doing much of anything to the surface.

Not speaking from experience here, as I almost never use Nagura, but just from knowing how hard they are... I don't see when a 2k Diamond plate would be needed to smooth out a benchstone after using them.

What a 2k would do is keep a very hard/slow Jnat "open" by peeling off any worn down abrasives on the surface and exposing new ones, similar to the way a 200 does for a washita that you let get clogged. So if your Jnat has a tendancy to get overly slow, a Diamond hone for slurrying will help with that.

Kind of the same reason a Diamond hone is so bad for slurrying a hard but aggressive coticule. On a hard, aggressive coticule, you get the best finish by LETTING the surface break in and wear down a little, and while a softer or equally hard coti slurry stone won't "refresh" the surface all that much, a Diamond hone will rip open the surface and give you a bunch of fresh, aggressive, big garnets. On a hard slow Jnat, that may be exactly what you NEED to keep the hone working well if it naturally has less aggressive/finer abrasives.

On a moderately fast stone though, I don't see it ever being needed. The stone will wear just fine under use and natural slurry stones and should only ever need to see diamonds if it needs to be flattened due to dishing. Just in my opinion.

 

[Steve56]

Jnats are their own thing. A mellow 600 Atoma will create finer acting slurry than a fresh Atoma 1200, and the fresh Atoma 1200 will scratch the hone while the mellow Atoma 600 will not. Maybe even a mellow 400 Atoma but mine isn’t mellow (yet). Do the scratches make the stone act coarser? I think yes but for how long IDK. Jnats seem to display the ‘Arkansas effect’ to some extent, the coarser thay are finished the coarser they act, but they will wear in and eventually glaze a little if they’re hard enough to be full on razor hones.

Mellow diamond plates are fine for jnat slurry (that’s all that Alfredo uses and folks don’t complain about his edges), but I prefer a matched tomo myself. A diamond plate will also remove any glazing and isn’t a bad thing to do once in a while with hard hones and tomo, and @SliceOfLife is right about this.

 

[Toro Blanco]

Definately a matched tomo! Jnats and cotis are another animal, kind of like tigers and lions. Similar but totaly different animals! I get a good edge with DN but a matched tomo was like " this is it". DN is fast and will refine but a matched tomo, you take it to a higher degree! IME
You must have a open mind if you want to learn. If they want to sell you something then have your radar on point but if they are not selling nothing the maybe they are tryin to help. This has helped me a lot cut through the fog.

 

[SliceOfLife]

Also, a good "tomo" can often times shore up weaknesses/flaws in a benchstone that isn't absolutely perfect.

 

[Atta Aikhjarto]

"Not speaking from experience here, as I almost never use Nagura, but just from knowing how hard they are... I don't see when a 2k Diamond plate would be needed to smooth out a benchstone after using them ."

Like i said, your silica particles are not even distributed in your jnat in the worst case they form a hair line a toxic line which stands out after some hours of honing with a good possibility in damaging your edge. Bigger clusters or lines are more embedded into the stones compared to smaller clusters or single particles with the results that the around surface get worn out quicker than those spots. Lesser and lesser high points which get higher and higher are somewhat equal to higher grit to the point where we say scratches happen. For a diamond plate this phenomenon is not relevant those clusters and lines will get cut down. I cant feel and see difference in edge quality or surface eveness or glance of my jnat with my broken in atoma 1200 with light pressure or a tomo.

Lets summarize. A matching tomo with a homogenous jnat is nice but they need to find each other in the first place and this takes time and luck. A diamond plate on the otherhand is more foolproof with results similar to a nice tomo.

 

[SliceOfLife]

A toxic line is a deposit of solid or nearly-so harder than steel mineral from a fault in the rock filling with something harder than steel rather than softer than steel, isn't it? Not just a projection of the silica distributed within the stone, no?

Diamond lapping will just flatten this toxic line down to the surface, it's still going to damage the edge as soon as it contacts it, won't it? Isn't that why toxic lines are typically dug out so that they are recessed below the surface of the stone?

I mean, I don't think diamond lapping a stone with toxic lines solves the problem, does it?

 

[cugel]

You can get away with using a diamond "nagura". I don't have great luck with some JNATs on plain water. Keeping a medium-light slurry keeps things moving. It's the fun part of JNATs. Get a few naguras when you get the chance. Using a JNAT, for me, is not about a honing equation; use synths for that.

 

[LJS]

I have one that if I don’t use a diamond plate I am convinced it loads up with specs of steel and kills my edge. Tomo doesn’t remove that and just glazes it. That one took me a while to figure out. I have come to prefer a well worn fine diamond when using and not really using any other nagura any more. It is a lot more consistent for me and you really get what the stone can do.