Juuma Cobalt Blue - How to hone Yasuki/Hitachi Steel

[Patrice]

Hi folks!

First post I guess on this section, hello to everyone.

I was wondering if someone has tried those synthetic Japanese stones.

Japanese water stones: Juuma Cobalt Blue | FINE TOOLS

Japanese water stones: Juuma Cobalt Blue

www.fine-tools.com

I have honed a Yasuki / Hitachi Special Steel a couple of weeks ago.

My King Hyper and Naniwa Chosera 1000 where barely grinding the steel.
Shapton pro was much better for that specific very hard steel but I was wondering if those Juuma were even better.
I have asked the seller but they don't seem to have an opinion - at least the one who answer to the emails...

More broadly, I was wondering what is your experience with honing those very hard steels.
I have changed my Kapton 4 or 5 times before I can have a good bevel and I find it annoying.
I'm a bit reluctant with Diamond stones, very expensive and so easy to wear out.

Any tips and tricks?

Good day to all,

Patrice

 

[Herrenberg]

Welcome to the section!

Never heard of those stones before.

I have not run into any difficulties setting bevels on Yasuki steel razors on my Shapton Glass 1000. Something sounds off here.

I don't think it's the steel hardness -- Thiers-Issard's C135 and Filarmonica's steel feels much harder to me than any Yasuki steel razor I have, and bevel setting is not a particular challenge even for those very hard steels. The only challenge on hard steels like that is finishing without disrupting comfort, and someone told me the trick for that: very slow strokes on the finisher. Worked for me.

Yazuki steel is intended to mimic the characteristics of tamahagane, I've heard, and that makes sense to me, because its hardness seems well in line with Japanese "Swedish steel" and the steel used in Heljestrand and Berg razors, as well as Japanese tamahagane razors. These seem harder to me than Solingen or Sheffield razors, but much less hard than the other steels I mention above.

I don't think it's the stone. Naniwa Chosera is the preferred bevel-setter for many straight razor shavers.

What I suspect is that you are bearing down on the spine, and having comparatively little effect on the edge. I was doing this too, early on in my honing. To fix this habit, I had to back way off on the pressure I was using, and then very gently torque the razor as I was honing, twisting it along the handle axis to gently favor the edge over the spine. Having to change your tape 4-5 times to set a bevel seems like a sure sign of excessive pressure on the spine relative to the bevel.

 

[Patrice]

Hi @Herrenberg !
Thanks for the advice, it definitely makes sense.
I don't torque the razor indeed, I'll try next time and will keep you posted.

 

[JPO]

I have changed my Kapton 4 or 5 times before I can have a good bevel

Yes, too much pressure on the spine. You should only need to do it before you move to the next stone after bevel set. A new razor should already have a good bevel.
It doesn't take much to flex the blade enough to loose contact over part of the bevel.

 

[Steve56]

At the link provided, the finest one seems to be 1200 grit with a 2000 grit coming later this year (2023). I hope that you are speaking about bevel setting only.

Yasuki steel (Hitachi White Paper #2) is very fine grained and one of may favorite razor steels. I do not find it particularly hard, though it is harder than most vintage Sheffield and Solingen steels, but not as hard as some vintage French, Swedish, and ice hardened steels.

A Shapton Pro works well, but the default synthetic line(s) for hard, wear-resistant steels are the Shapton Glass HR and the Shapton G7 series. A Naniwa Chosera should also have no issues, but the Chosera 1k at least, does tend to load up with swarf.

It does sound like you’re putting a lot of pressure on the spine.

 

[Gamma]

I've honed a bunch of Yasuki steel Kamisori. Most were NOS.
I never put one on a 1k - that will wear the omote excessively.
The bevels on those Kamisori came around fine on a 3k Chosera.

I had a few western type Yasuki also, they saw a Chosera 1k, no issues there.
No tape needed on any of them...
Honing on tape usually requires several changes of the tape during bevel set though, that's not unusual IMO. When I do use tape I don't use kapton to hone because it can embed into the stone and slow it down.

I think the hardness of Yasuki razors is typical for what I see in most Japanese razors. Very hard but not stupid hard. The wear resistance is a bit higher though it seems.

I can't compare Yasuki to Tamagahane - first, Tamagahane isn't just one thing that behaves one way.
IME, Yasuki razors I have sharpened all sorta feel the same on the hones, while not all Tamagahane razors feel the same on those same stones. The Tamagahane razors did not feel like Yasuki on the stones either.
I had a Tamagahane Iwasaki Western and it honed surprisingly easily actually.

Those blue stones are aluminum oxide based, same as most water stones like Chosera, etc. I doubt the abrasive content is so high that you would see miracle cutting happening.

 

[Patrice]

Thank you folks, that's really interesting, I'll answer you later on after my work day.
In the meantime I received a more informative answer from Dieter tools, they say Juuma and Shapton pro are barely the same.
@Gamma, I had a quick look at your website, it's really impressive, I'm very interested by your experience because I had the same with Kapton. More soon, have a great day meanwhile.

 

[Bayamontate]

In this particular circumstance, start at 3K or 4K land and treat the razor like it‘s stainless steel, more work with a lighter touch. Your first instinct will be to use more pressure to move more steel quickly, work to not do this and let things get done at a comfortable speed and pace. Working with harder steels create many liabilities like flex, deep scratches, uneven topography etc. Patience is diligence are key, have fun!

 

[Patrice]

Yes, too much pressure on the spine. You should only need to do it before you move to the next stone after bevel set. A new razor should already have a good bevel.
It doesn't take much to flex the blade enough to loose contact over part of the bevel.

Hi @JPO, yes, that's usually how I proceed but this specific blade is really hard and it does not grind the steel as expected.

 

[Patrice]

BTW, it's a Vintage Manaslu M500 Straight Razor 6/8 Osaka Tokyo Nichiri with Y.SS2.H Silver Steel inside (and I love it!).
Half hollow, I guess.
In case someone has tried it on a stone.

 

[Patrice]

At the link provided, the finest one seems to be 1200 grit with a 2000 grit coming later this year (2023). I hope that you are speaking about bevel setting only.

Yes! I'm a beginner but not that beginner...

...the default synthetic line(s) for hard, wear-resistant steels are the Shapton Glass HR

That's good to know. I have tried it in my beginnings but I didn't like it, I found it too synthetic if you see what I mean. Like the Naniwa SS. But maybe I should try it again.

A Naniwa Chosera should also have no issues, but the Chosera 1k at least, does tend to load up with swarf.

In that case, there was absolutely no swarf on the Chosera 1k.

It does sound like you’re putting a lot of pressure on the spine.

Not more than on the edge I guess, I need to look at this aspect more closely to understand how to do it correctly.

 

[Patrice]

Hi @Gamma ! very nice to see you around and have your advice, your background is really impressive...

I had a few western type Yasuki also, they saw a Chosera 1k, no issues there.
No tape needed on any of them...

That's interesting! You can create your bevel on the 1k without damaging the spine?! How do you do that?

Honing on tape usually requires several changes of the tape during bevel set though, that's not unusual IMO.

That's reassuring.

When I do use tape I don't use kapton to hone because it can embed into the stone and slow it down.

Ah yes, I hate it! What tape do you use?

Those blue stones are aluminum oxide based, same as most water stones like Chosera, etc. I doubt the abrasive content is so high that you would see miracle cutting happening.

Yes, I guess it's not the direction to take apparently.

 

[Patrice]

In this particular circumstance, start at 3K or 4K land and treat the razor like it‘s stainless steel, more work with a lighter touch. Your first instinct will be to use more pressure to move more steel quickly, work to not do this and let things get done at a comfortable speed and pace. Working with harder steels create many liabilities like flex, deep scratches, uneven topography etc. Patience is diligence are key, have fun!

How do you deal with it? Circles? X strokes?

 

[Patrice]

Regarding the torque thing, do you all torque the razor when you set the bevel? I have learned with videos of @alx gilmore and he does not seem to torque the razor but maybe he does and I don't see it?

 

[JPO]

What is the bevel angle?
Sometimes it can be difficult to close the apex on razors with hard wear resistant steel and acute bevel angles. Most steel have an elasticity modulus that are quite close. So, harder steel might not be that much stiffer.
As the wear resistant increases you sometimes need a little more pressure to cut the steel effectively. If the bevel is to thin you might flex the apex off the stone. Getting a clean apex can be difficult if this is the case.
I have a woolfblades razor that had a bevel angle around 14 deg. It was also really hard. To be able to hone this I had to add an extra layer of tape for the final finish. Some stones did not cut this steel well. The shapton glass stones worked, but it was like I was honing hard piece of glass.
I baught an identical razor, and asked for a softer hardness. This was also thinner ground. This was much easier to hone. He actually changed his hardening process after this.

 

[Gamma]

Hi @Gamma ! very nice to see you around

That's interesting! You can create your bevel on the 1k without damaging the spine?! How do you do that?

What tape do you use?

Western razors are designed to be honed with the spine on the stone. The spine and edge wear identically and this maintains the bevel’s angle. The wear is not damage, its just a wear pattern.

I use 3M electrical tape; either Super 33, Super 88, or Temflex 1700.

 

[cugel]

BTW, it's a Vintage Manaslu M500 Straight Razor 6/8 Osaka Tokyo Nichiri with Y.SS2.H Silver Steel inside (and I love it!).
Half hollow, I guess.
In case someone has tried it on a stone.

I had the same razor. I agree that steel is hard but I managed to hone it, probably starting with a chosera 1k then 3k and 8k superstones

 

[Bayamontate]

How do you deal with it? Circles? X strokes?

I’m a circle, snake stroke, figure 8 stroke, chisel stroke etc. guy but gauging pressure is key, use enough to get where you want to go without adding complications to any given stage while reaching the ultimate goal.

 

[Gamma]

I would suggest checking out some different YT channels for honing direction.

If you were attempting to set a bevel on a razor using a 1kC and there was no swarf, the issue is your technique, not the brand of stones, or the type of steel, or bevel angle, etc.

 

[alex1921]

Can you show a picture of the razor. I am curious how it looks up close after all these attempts.