# Thinning JCK Nashiji, what is happening here?



## Twister (Aug 20, 2013)

I had the first thinning session for a JCK Fu Rin Ka Zan W1 petty. http://japanesechefsknife.com/FurinkazanW1Series.html#FuRinKaZanWhiteSteel#1Series
Started with King1000 stone and after a while swithced to King6000.

These are pics after ~5min of work with King1000:










What is happening here? Why does it turn into blunt grey? Is it drawing material from the Nashiji finished Hira, which then sticks to the part between Shinogi and Hagane, or what?
It originally looked like at JCK website; shiny metal colour with deep grinding scratches.

Here are pics after ~15min with King6000:
(I thought to move to safe side and continued with 6000 when I did not know what was happening...)









Firstly, is my understanding correct here:
1 = Hira, Nashiji finish
2 = Shinogi line
3 = Kireha, this part is stainless clad, or?
4 = "Hagane line"
5 = Hagane, White no1

Secondly, what should I do here?

- Take King1000 into action and give it a lot more work?
Would this cause part 3 (Kireha?) to lose its cladding and end up in situation where everything below Shinogi is just White no1?
How thick is the cladding in part 3?

Resulting in somewhat thinner knife would not be a problem, actually I would prefer it.


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## schanop (Aug 20, 2013)

Nothing bad is happening here, pretty much bevel comes not totally even, and you have not finished evening it out yet.. If you like a good looking knife, get king 1000 to work until you have even colour and no more rough grind marks left on the blade.


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## Rottman (Aug 20, 2013)

Looks like the stainless cladding is as gummy as on the Hiromoto AS line. Many stones just leave a very dark finish on the cladding...


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## MowgFace (Aug 20, 2013)

Try going back to the 1k stone and work up some mud, and lighten up on the pressure. Repeat for the 6k. See if that improves the contrast.


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## MowgFace (Aug 20, 2013)

Scratch my last post, if you're trying to have the whole bevel shiny. I would try more pressure.


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## cheezit (Aug 20, 2013)

Isn't this caused by the difference in hardness between the hagane and jigane and how they take to being abraded? I've seen a similar finish applied with a bocashi wire brush; the brush is hard enough to abrade the soft outer cladding (jigane) but not enough for the carbon steel core (hagane).


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## bkdc (Aug 20, 2013)

It's an uneven bevel finished on a grinding wheel, and there's nothing wrong. It took me hours to thin out my Fujiwara Teruyasu nashijii. I thinned out the nashijii portion as well until I got most of the spine to 2mm or thinner.


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## Benuser (Aug 20, 2013)

Rottman said:


> Looks like the stainless cladding is as gummy as on the Hiromoto AS line. Many stones just leave a very dark finish on the cladding...


+1
It's not so much about the difference in hardness, it's more about the soft clad being much more abrasion resistant.


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## ThEoRy (Aug 20, 2013)

For thinning I would use a lower grit stone like the gesshin 400 or beston 500. This way you get in, flatten the blade road, cut the cladding quickly and get out. Less time spent on the stone is less time wobbling around and making mistakes. Then move up to the next grit to achieve the scratch pattern you wish to have like the king 800 for example.


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## labor of love (Aug 21, 2013)

thinning is the downside of stainless clad knives. i learned how to thin on a tojiro dp. i definitely made a mess of that knife.


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## Twister (Aug 21, 2013)

Got it to this state last night. Took me almost 2 hours, but I took it as learning...

I had to go between 1000 and 6000 quite many times. Every time I returned to 1000 - instant dull grey all over.
Also difficult to see what is beneath that grey layer. So when back with the 6000, more scratches revealed. This happened many times.
At the end I almost felt like crying when most of the grey was cleaned and then saw scrathes again and new I had to go back to 1000 and thus back to a lot of grey :surrendar:

Getting rid of the grey with 6000 was also something really strange. During the 2 hours it seemed when I held the knife 45° to the stone, like when sharpening, the grey just did not reduce.
I tried just about everything - varying the angle (of "knife handle to stone"), pressure, placing of fingers, how much mud on stone and flattened the stone few times during the session.
At the end, only turning the knife to 90° to stone and going with lightish pressure seemed to make a difference and worked the best. Touching up with newspaper also took some of the light grey which the 6000 just did not reduce.

So next time thinning and polishing this knife, I'll get some coarse stone, like Gesshin 400, and also have a go with the nashiji part. Just to get some challange and learn more :crazy:
Perhaps some extra high grit polishing paste might be worth a try? Or perhaps a loaded strop?


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## ThEoRy (Aug 21, 2013)

I'll say this too, you have stumbled upon a good technique. When creating a kasumi finish, it is light pressure when working in the mud which achieves the best results. So, work up a mud then play around in it with only the weight of the blade as your downward pressure and you will see a more even scratch pattern and or kasumi finish depending upon the stione.


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## harlock0083 (Aug 24, 2013)

Did you request the thinner profile from Koki?


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## Squilliam (Aug 25, 2013)

It sounds like you're very confused to me. You should not be trying to make the wide bevel all the same reflective colour. The soft cladding is meant to turn dark on your stones, using low pressure helps. It's called kasumi and it looks nice. It's the finish many natural stones leave.

Check out this thread for more: http://www.kitchenknifeforums.com/s...w-and-how-to-maintain-polish-on-single-bevels


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## zitangy (Aug 25, 2013)

Twister said:


> I had the first thinning session for a JCK Fu Rin Ka Zan W1 petty. http://japanesechefsknife.com/FurinkazanW1Series.html#FuRinKaZanWhiteSteel#1Series
> Started with King1000 stone and after a while swithced to King6000.
> 
> These are pics after ~5min of work with King1000:
> ...



RGds d


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## ar11 (Aug 25, 2013)

Not sure if it helps, but I've been trying to thin my Tanaka on a King 1k/6k combo. Noticed a lot of the graying issues you noted. After a lot of back and forth on stones decided to hand sand with 1000 grit wet sandpaper which was already pretty loaded. The second pic is after 30 secs of scrubing, I still had work to do on the heel but you get the idea. You can still see scratching from the sandpaper in the after photo, but I used #000 steel wool as a followup and it got rid of most of the scratching. Probably going to use my oscillating multitool to polish up the blade to a nice shine. 

*one thing i learned the hardway not to do was rub BKF onto the carbon blade because it creates random greying discoloration which can be a PITA to take out. 

Before






30 sec after


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## Twister (Aug 26, 2013)

harlock0083 said:


> Did you request the thinner profile from Koki?


Yes I did, but after my purchase it went sold out, so I probably got what was left in stock. Little over 2mm thick.

Thanks to all for helping here. I am very happy with the knife now.


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