Question for Jnat Experts

[quijas23]

I'm hoping I can get some Jnat pros to chime in on some issues I am having on my Nakayama Asagi Mariuchi. I have been honing on it and suddenly I felt like something was a little "scratchy" sometimes. Decided to get out the 90x scope and I have something that keeps popping up no matter how much I flatten it (with a atoma 1200). Under the scope it looks like little salt pieces (Not as big , but are white and look similar to salt under the scope.). I am wondering if I somehow got a layer of undesirable sediment or something like that in my stone (its a natural stone so I am aware that these things are not perfect).
Can I flatten the stone to get through this? is this normal? What should I do?
Unfortunately, this was my most expensive stone by far and while the shaves were great off of this at the begining (I remember going through my whole normal progression and then doing 20 or so swipes in slurry on the stone and being amazed at how great the shave was), It seems the performance of this has dropped off and I am assuming it has to do with the particles that I am seeing.
Not sure if this is normal or not. I also managed to get a picture of the particle if I could forward it for someone to take a look at. I will be totally bummed if this is what is called inclusions or some other undesirable particle in my stone. I have resorted to using my stone by going first with the spine as one would when stropping - this seems to clear the bigger particles and seemed to improve the shave, but I certainly didn't do this at the begining when I first got this stone.

 

[David]

Can you post a pic of the stone and the particle?

 

[cotedupy]

I'm afraid that does sound like a slightly toxic inclusion in the stone I think, there are ways to fix it though .

As David said - if you post some pics of the stone people might be able to advise what's best to do. Depending on how it's positioned and orientated you may be able to lap through it, or alternatively you may be able to 'dig it out'.

 

[David]

It sounds like those surface fissure that you see in harder stones. If that’s what it is, there’s a chance you can lap through it. Pics will help.

 

[cotedupy]

It sounds like those surface fissure that you see in harder stones. If that’s what it is, there’s a chance you can lap through it. Pics will help.

Yeah, I've got a couple of those in an old asagi I have. Though touch wood - atm they can't be felt and don't release anything.

 

[Steve56]

Yep, need pics

 

[Leelight66]

Can you post a pic

 

[quijas23]

Here is a pic of the particle
As mentioned before, no matter how much I lap it still shows up

 

[quijas23]

Picture of the stone…

 

[Gamma]

No, it' not normal.
I can't tell what it is because the image isn't that clear. Guessing doesn't help.
Honestly, what it is and why it's there doesn't matter. What is important is that it needs to go.
Sometimes, light lapping won't make stuff like this go away easily because the inclusion is deep and much much harder than the surrounding stone. So the surrounding stone wears faster.
For stuff like this, I lap with a 140x plate so i can clear material faster.

Lapping might get you past the issue. It also might reveal other instances of the same thing in other places.
Rarely is there only 1 single inclusion in a stone. But it does happen that way sometimes.
Often, multiple inclusions all live in proximity to each other though, like - in a layer or a in a nest.
The thickness of the layer is unknown, can be small, or large. A nest can get bigger deeper in the stone.
There can be multiple layers separated by good stone.
So you can get past the stuff sometimes but then it comes back. Or not.

Typically, I'd try to dig something like that out. Gently. Very very gently.
BUT - I don't recommend that unless you are willing to deal with a proverbial can of worms.

To give you an idea, years ago I popped something like that out once, and it turned out to be the spearhead of a toxic vein that ran through the stone on two axes. I had to split the stone on the vein, cut away the toxic parts and ragged edges and then try to salvage the left over pieces.
Another time I had to lap a Suita for an hour, lost 1/8" of stone, but wound up with a perfect surface, and that inclusion looked very much like yours actually.

Be careful with your diamond plate, very hard inclusions that are deeply embedded can wreak havoc on them.

 

[GreazyThumbs]

I am not seeing any inclusions in that stone, nothing obvious. Any pictures of where you think the inclusion is?

Are you sure this is not from you diamond plate or your nagura, your base stone looks uniform and clean to me?

 

[Steve56]

It almost looks like it’s casting a shadow

 

[quijas23]

Went at it again tonight and it seems that I might be losing stones off of a dmt diaflat stone. Normally I never use this on flattening but when I switched to a dmt duoflat, I could not reproduce the problem. GreazyThumbs, thanks for the suggestion, I think this solved the problem. This doesn't seem to be an issue in flattening other lower grit stones; However, I'm guessing when you get to this level of hardness, one small thing has the potential to mess up and it seems that using a not so great plate is the problem.
Once again, The forums here help immensely. Thanks to all, much appreciated.

 

[Herrenberg]

Went at it again tonight and it seems that I might be losing stones off of a dmt diaflat stone. Normally I never use this on flattening but when I switched to a dmt duoflat, I could not reproduce the problem. GreazyThumbs, thanks for the suggestion, I think this solved the problem. This doesn't seem to be an issue in flattening other lower grit stones; However, I'm guessing when you get to this level of hardness, one small thing has the potential to mess up and it seems that using a not so great plate is the problem.
Once again, The forums here help immensely. Thanks to all, much appreciated.

Very interesting. I'm adding to my "reasons to avoid DMT" list.