Thinning: Round 1

[Anteater]

I've finally embarked on my first ever thinning project - a Yoshikane 210 clad W2 gyuto. My lowest grit stone is a Chosera 800, which many folks have told me will turn thinning into an absolutely grueling process, but I put in a couple of hours on it tonight because I figure, "hey, this is a decent way to get the hang of the process while minimizing risk to the blade, and when I get fed up I'll just get a lower grit stone."

I did end up doing a few hours tonight and here are the before and after choil shots. It's not very different at all, but I feel like I can see the shoulders behind the edge starting to thin down. I suppose the proof will be in the proverbial pudding of cooking dinner tomorrow and seeing how the knife feels.



I was curious....

1) what do folks think of the progress so far?

2) what would y'all recommend moving forward?

If nothing else, I feel like I'll be more comfortable moving on to a lower grit stone to really get into the meat of the process than I would have been without starting on the 800, and I feel like I've also pushed ym sharpening ability forward by really paying close attention to the blade angle across the stone for a few hours straight.

 

[M1k3]

At least you're seeing progress. Just keep it even. I'd definitely recommend a coarser stone. Definitely not a Naniwa Super Stone 220... King 300 is cheap, but, not the fastest for a 300, but it'll be faster than your 800. Shapton 120 or 320 (220 is super muddy ). Cerax 320. Gesshin. Sand paper. Diamond stones/plates.

 

[zmaster]

I can definitely see progress there! Hopefully you were able to feel the difference.

I would definitely go coarser/lower grit as you and others have already mentioned. That'll let you get more noticeable results in a much much shorter time (e.g. 2 hours instead of 10 hours). I embarked on my first hand-thinning journey almost a year ago and spent many many hours on the lower grits. Since I needed to remove so much material, I actually went down to 40 grit wet-dry sand paper and worked my way up. Here's the link to my first thinning journey on a cheap Forgecraft knife:
https://www.kitchenknifeforums.com/threads/forgecraft-project-knife.38533/

Now a year later, I have found that I strongly prefer my knives be really thin behind the edge—so thin that it will bend/deflect when you press the edge laterally against your nail or some kind of rod (check out Kippington's post #6 in this thread: https://www.kitchenknifeforums.com/...the-edge-anyway-and-kujira.42359/#post-624353)

After cutting with a knife that thin behind the edge, everything else just seems to be too dull. You could probably achieve the same "brass rod test" thinness with your Yoshikane by focusing on thinning area just a few millimeters "behind" the edge. That way you won't have to remove so much material and won't dramatically change the cross-sectional geometry.

Here's a picture of my recently thinned 240mm Masamoto KS. For this one, I spent about 30 minutes on a Gesshin 220 stone to accomplish the bulk of the thinning. I then spent another 20 minutes basically removing scratches on a Gesshin 400, JNS 800, and then Shapton 1500. The edge feels noticeable sharper because the knife is much thinner behind the edge and thus has a much more acute angle behind the edge.

Keep up the work and we'd love to hear about your progress!

 

[Stonetherapy]

That looks great @zmaster, did you manage to maintain some of the blades original convex nature?

Asking for a friend...

(Not really, about to have a go myself!)

 

[zmaster]

@Stonetherapy Thanks! Are you referring to the Forgecraft knife or the Masamoto KS?

Both knives have a pretty flat "wide bevel" at this point. The Masamoto KS's flat wide bevel is about 12 mm high, measuring from the edge. So the original grind of the knife above that 12 mm "wide bevel" is untouched.

The Forgecraft on the other hand, has a ton of material removed and has a really wide bevel as you can see from the photos in my other thread. However, there is still a bit of convex geometry near the edge of the knife, a tiny hamaguri bevel about 1.5 mm tall. You can see this in some of the pictures.

 

[Stonetherapy]

Great work on the Forgie, but I was looking at the KS. Wanting to thin mine without losing the excellent grind has had me hesitating, even though I want it thinner BTE.
Mainly want to maintain some food release.

 

[Keat]

Crazy KS choil shot.

To OP I wold definitely order a lower grit stone. Also, what yoshikane is this? I thought the w2 was wide bevel...

 

[Anteater]

zmaster, those are some wild choil shots! I'm definitely curious to see how super thin knives feel. My plan is to pick up a Gesshin/Ashi Ginga before too long and see how I like it, and let that inform exactly how far I go with the Yoshikane.

what yoshikane is that

I believe it may have been called "Migaki?". I got it from panda on here maybe a year or so back and he said it was an older make that wasn't in production anymore. Definitely W2 and definitely clad in stainless, but apart from that I haven't been able to, say, Google "Yoshikane Migaki" and bring up a store page or anything.

 

[labor of love]

Yeah, it’s very very old stock. Really sweet blade and heat treat. Much prefer it over modern Yoshikane carbons.

 

[rickbern]

anteater, I just took a picture of my ginga's choil yesterday, you may find it helpful.

I think I'm going to thin it a bit soon, it's feeling a bit thick. BTW, this is the stainless model.

Oh, and I heartily agree with the conventional wisdom, get a coarser stone. First knife I thinned I almost used half a gesshin 400. The difference between a 220 and a 300 or 400 is pretty large, I imagine your 800 is even more difficult to remove metal with. But you're definitely making progress, seems to be a pretty big difference.

The best advice I got the first time I thinned was to make sure your non-dominant (left in my case) hand is exerting pressure a fair bit away from the edge. Wherever your left hand fingers are, that's where you remove the steel. FWIW, I start with a generic 220, then I use a JNS 300, a Gesshin 400 (seems redundant but I do it) and then a Gesshin 2000

Gesshin Ginga:

I also shot my Wakui. This is the "out of box" thinness with this knife. I kind of think a knife like a wakui or a kochi is actually thinner behind the edge than a laser, but the laser has a thinner overall geometry.

 

[JBroida]

that ginga isnt new is it? That looks way to thick to be new

 

[rickbern]

Jon,

Nah, it’s about three years old. I was getting ready to start thinning it so I took the picture.

Did round one this morning, I’m sure I have another one to go.