Removing toxic lines from Japanese natural stone.

Hello there!!

I brought my Red Oohira stone from last JNS gathering in November. Maksim couldn't sell it because of the toxic line or inclusion which goes through half lenght of the stone and almost through whole deepness of the stone. It splits it in half. Of course you can cut this stone and make tomo nagura's, small traveling size stones or fingerstones, but I wanted to save it.

I have postponed that project for a while, but now I found some time to remove it. I have never removed toxic line before so this is more like a experiment.

Let's start from ''the toxic line'' or ''inclusion''. What is that? The quote below comes from Easternsmooth.com blog:

http://easternsmooth.com/blog/jim-rion/2011/10/24/703-buying-japanese-hone-guide-beginners

''There are two basic types of inclusions: lines (called Suji?) and specks, called "hari" or "ishi" or sometimes "Suna-me" or sand eyes. Basically, these are accretions of minerals that are harder or of a different coarseness from the rest of the stone. If they are in areas that can hit your edge, they are called "living" and are best avoided if possible. If they don't hit the blade, they are called "dead" and, of course, aren't a problem. Both cases, however, can cause a drop in the price of the stone.''

So here it is. My Red Oohira:







So here you can see my line going through the whole depth of my stone.


And here line is going through the lenght of the stone.




Let's look at it in the 60x magnification. Please note that I took those pictures with phone camera and some kind of magnifier so colours might be little bit different.








So my today's tool of choice was my girlfriend's manicure set...

and diamond covered bit.

I was gently removing the lines.



It was going ok, but then I hit the first dangerous place. It's on the rounde corner. Later on I will show you all dangerous spots.



Look at it under magnification. You can clearly see that there are different coloured minerals. My diamond bit felt slippery on those spots. I felt like bit was jumping over that place. It was too hard to remove. Almost dulling my diamond bit.





Here you can see all spots.





















I couldn't remove them so I've decided to soak stone in water for few minutes to soften it.

And after a little bit of soaking and working with my girlfriend's rotary tool I found this:

You can see some kind of yellow crystal or something. This can easily chip your edge.



This is how it looks after the job was done.



Then I used my Atoma 140 and very hard worn DMT xcoarse (which is ultra fine now) to flatten the stone.


Of course I have rounded the sided as well.

And then with help of Tenjou nagura I have rounded the gap corners.







Looks scary big, right?







But gaps are clean now and this is important:









It was time to test it. I used my Suisin Densyo White#1 270mm yanagiba. This is how it looks before:








And after Red Oohira.



This stone scratched my yanagiba. I left it for a day...

and next day I started from the very beginning. I have polished my blade with JNS 800, White binsui and Red aoto so I was sure that there are no deep scratches.
This is Red aoto finished blade with uniform scratch pattern:









Short movie. Unfortunately memory in my phone was gone seconds before end of the movie:




And after

As you can see, I could use whole stone and it left uniform scratch patter.











That's it. As you can see, I can use that stone same as other stones. my toxic lines doesn't affect sharpening and there is no risk of chipping the blade.Now I know that toxic lines are not that scary and I got a great stone for a very small amount of money. Thanks for watching and take care...

 

Nice.
I was thinking that lines are called toxic because they are… well, toxic! Not because they just have some carbides to chip/scratch your blade.

Actually now you have to scratch a dragon on your stone.

 

Hehe. I will Anton

 

the red oohira leaves a beautiful finish. i see why you wanted to keep it so bad! good work......


How many times of sharpening on this stone until you will need to remove more of the line?

 

Brad I would keep that stone anyway I really don't know answer for your question. This stone is quite hard so I think that plenty of times. As you can see grooves are very deep so I don't think that it will happen in the near future. Also next time I can try to remove only hard spots instead of making grooves.

 

I just noticed that there is no movie in my post. Propably I didn't copy it from my blog. Here's the movie:

 

i envy your natural stones. i only have a suehiro rika for finishing. i hope that i can get a good natural sometime in the future

 

Brad there is nothing to envy. Many of us have plenty great stones, but to be honest how many of them are people using? I have about 16 - 17 stones, both synthetics and J-nats, but I am using only two for most of the sharpening tasks. JNS 1000 and White binsui. Really. Sometimes I am using Red Aoto and sometimes other stones, but mostly only two.

 

I envy your skills

 

Nice work and admirable patience and attention to detail! Well done Bathon UK.

 

Really well done! I like the close up shots and your approach.

 

That is pretty damn cool. What kind of edge does the ohira leave? I've been eyeballing them as a potential tax refund object.

 

I really enjoy your tutorials, Greg. Very instructive and an obvious display of both talent and skill, not to mention patience. Keep it up!