Toxic: what is it? What does it mean?

I have four JNATs: a red Akapin (aoto), an Amakusa, a Takashima, and a Yaginoshima with a Mejiro Nagura. I will be getting more JNATs from time to time, as I have it bad.

I've read time and again that a stone shouldn't have any "toxic lines" or something like it. In the natural stone context, what is meant by "toxic"? Is it poisonous? Is it a vein of asbestos? Or is it just an geologic occlusion that affects sharpening? How worried to I need to be were I to find I had a toxic stone? Would I need to get it out of my house? How do I distinguish between a toxic stone and one that is not toxic?

Thank you for any clarification.

Cheers,

Jack

I think that refers to inclusions, other natural materials impregnated in the rock, that are harder than the hone proper, and will damage your blade when you go to hone. A good seller should guarantee that the hones he sells can be returned should this be the case. If there are inclusions, lines whatever, that are softer , and will not effect the honing , it is strictly a cosmetic issue. Sometimes they make for a better looking hone.

Toxic would mean any impurities that are Harder than the rock itself.
Spots, lines, holes and whatever it may be are no issues at all really, unless they are harder than the honing area itself.

It is a bit of a challenge to identify sometimes, and that is why a well renowned seller is imperative.
Hones with inclusions and impurities can be pretty as all that, but their honing abilities could be heaven or it could turn out to be hell:)

Edit:
The previous poster may be old as old that, but he still got the speed alright;)

What'd your reference to the "toxic" term. I've never heard that term used before and I have somewhat of a geology background. There are some minerals that contain toxic substances but most aren't in a form that would harm you by handling. Even asbestos won't harm you unless you play around with it or work in a quarry.

As said above a toxic inclusion is harder than the rest of the stone and will scratch the bevel of any tool(razor, plane blade, knife, chisel etc.) that is sharpened on such stone.

I've seen togishi (Japanese sword polishers) dig them out of the stone and put the stone back to work. That might save you some postage if the bad bits weren't very deep and the stone was expensive enough to want to save.

Good topic, attached are pictures of a Toxic Japanese natural stone with a slurry stone from the same rock. This is a very fast cutter with slurry. This is a difficult stone to use because of
1. Size and shape
2. Toxic needles in stone matrix.
This stone will take a 3K edge all the way up to a finished edge in a matter of minutes. It will also destroy the edge if you are not very careful and stop when you reach maximum edge potential from this stone
A great deal of lapping on this stone has calmed it down much. There are still toxic needles (iron pyrite etc) which can peel off whole sections of the edge. Kelly (nun2sharp) borrowed it for some fun, maybe he can chime in.
MIke
http://i.imgur.com/fFCws.jpg

http://i.imgur.com/dWUqj.jpg

http://i.imgur.com/I6iJo.jpg

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Originally Posted by jackslimpson

I have four JNATs: a red Akapin (aoto), an Amakusa, a Takashima, and a Yaginoshima with a Mejiro Nagura. I will be getting more JNATs from time to time, as I have it bad.

I've read time and again that a stone shouldn't have any "toxic lines" or something like it. In the natural stone context, what is meant by "toxic"? Is it poisonous? Is it a vein of asbestos? Or is it just an geologic occlusion that affects sharpening? How worried to I need to be were I to find I had a toxic stone? Would I need to get it out of my house? How do I distinguish between a toxic stone and one that is not toxic?

Thank you for any clarification.

Cheers,

Jack

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As mentioned before, there's nothing dangerous to you when the word toxic is used. It's just one of the vagaries of transslating from one language to another where multiple words exist with same or similar meanings. In reference to Japanese metalworking, swords/knives, it's more commonly said as a fatal flaw, meaning it kills the quality of the object in question. Of course there's also the other implied meaning that if this flaw caused the sword to break, it could be fatal to the user!

Same thing though, it's just a matter of the quality of whichever original translation took mainstream acceptance first & whether it took context into consideration or only the literal meanings of the words.

I have had these stones for a while now, probably a little longer than I should. Thanks Mike! I have to tell you that I have never been so excited about a stone. This stone will take a razor once the bevel is set and finish it, if there ever was a one stone hone this is as close as you are going to get.

The down side is that if you dont know when to stop, the edge is finished, not sharp, but kaput, destroyed, disintegrated! Thus the term "toxic". I was honing an edge after the bevel was set and wanted to see how far I could go, I was doing great but wanted just a little more so back to the stone, within about 30 seconds I noticed the slurry had turned to a steely gray with silvery specks. Whats this?! I pulled the blade from the hone, wiped it dry and got out the microscope. The edge was beyond shot, it had disintegrated, saw toothed, big chunks, little chunks, all sorts of metal missing. I had to start over.

BTW The inclusions are the color of rust, Iron would be my guess.

It reacts differently to different steels as most stones do, but with this one you had better pay significantly more attention Some steels you can finish, some had better finish on another stone.

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Originally Posted by nun2sharp

I have had these stones for a while now, probably a little longer than I should. Thanks Mike! I have to tell you that I have never been so excited about a stone. This stone will take a razor once the bevel is set and finish it, if there ever was a one stone hone this is as close as you are going to get.

The down side is that if you dont know when to stop, the edge is finished, not sharp, but kaput, destroyed, disintegrated! Thus the term "toxic". I was honing an edge after the bevel was set and wanted to see how far I could go, I was doing great but wanted just a little more so back to the stone, within about 30 seconds I noticed the slurry had turned to a steely gray with silvery specks. Whats this?! I pulled the blade from the hone, wiped it dry and got out the microscope. The edge was beyond shot, it had disintegrated, saw toothed, big chunks, little chunks, all sorts of metal missing. I had to start over.

BTW The inclusions are the color of rust, Iron would be my guess.

It reacts differently to different steels as most stones do, but with this one you had better pay significantly more attention Some steels you can finish, some had better finish on another stone.

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Doesn't sound "Toxic" at all to me, looks more like you over honed and the false edge came loose an messed your edge up, if it's truly toxic you can't just hone a little and get away with it.

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Originally Posted by Lemur

Doesn't sound "Toxic" at all to me, looks more like you over honed and the false edge came loose an messed your edge up, if it's truly toxic you can't just hone a little and get away with it.

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Yes , I thought toxic referred to sand or other inclusions that damage the steel from first pass. If you can get a finished edge from bevel set it is simply a very fast stone. They are fun to use but you can't go past that sweet spot without consequences.

Yes you are correct. Over honing and destroying the edge can be useful when determining a natural stones (and the steels) performance characteristics.

Thank you for the clarification OZ. Can a toxic Japanese natural stone shed layers, stabilize and become less toxic or useable? Can a natural stone shed layers and revert to become more toxic or un-usable?
Mike

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Originally Posted by MODINE

Yes you are correct. Over honing and destroying the edge can be useful when determining a natural stones (and the steels) performance characteristics.

Thank you for the clarification OZ. Can a toxic Japanese natural stone shed layers, stabilize and become less toxic or useable? Can a natural stone shed layers and revert to become more toxic or un-usable?
Mike

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S'ok Mike.
When you're talking natural anything is possible but if there are obvious 'toxic' inclusions in the first place they may possibly come & go with lapping tho the amount of lapping can be variable. I've heard of people digging out a line sand or pyrites to make the stone usable or if the stone is large enough avoiding the are. Pic below shows an obvious line of iron oxide Approx 20x mag. There are stones with lines & colouration that are harmless however, so you can't generalise.
If the stone is a quality stone it is less likely to reveal inclusions over time. Vague enough ? :)

Well anyway, my experimentation with these beautiful stones are over, Sham invited me over for dinner last nite and unbeknownst to me, Mike was hiding behind the door, he got me down and made me cry uncle until I gave them back. But all is well that ends well, We had a great dinner with good company. Myself, Sham, Mike/Modine and the ever lovable Obie!

I forgive you Mike, but keep an eye out!

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Originally Posted by onimaru55

I've heard of people digging out a line sand or pyrites to make the stone usable or if the stone is large enough avoiding the are.

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indeed, that is common practice in the world of Japanese swords. It still depends on the size/orientation as you'd want the item being worked to glide over the groove on an angle, not hit it squarely & catch or bounce.