Problems sharpening Japanese kitchen knife

[Jamey Howard]

Hi everyone. I’m having a nightmare trying to sharpen a knife and would like some advice.

My girlfriend very kindly bought me a Teruyasu Fujiwara knife for Christmas. The knife is a Maboroshi no Meito Petty (150mm). It’s made of shirogami #1 carbon steel (white steel #1), forged between layers of stainless steel, Hrc 64-65.

You can see more about the knife here:
http://www.epicureanedge.com/shopexd.asp?id=87906

And here’s a photo:

So today I sat down to give it a sharpen. It was fairly sharp when it arrived, straight out the box, but I was sure I could get a keener edge on it, especially since the steel is 64-65 RC.

I started with the 400 grit diamonds and because I have the low angle adapter I decided to try 10 degrees per side (20 degrees inclusive). It seemed to take forever to get any burr but I was expecting that because the steel is so tough. However even when I finally started to get some burr it was only at the ends of the blade. So there was some burr near the tip and some burr near the heel but no burr at all in the middle part.

So I kept going and the burr at the ends seemed to grow a bit but the middle still had an area with no real burr. But i’d been going so long with the 400 grit stones I thought I must surely have reached the apex. so I went up to 600 grit and then my normal progression >> 800 >> 1000 >> 1200 ceramic >> 1600 ceramic >> Balsa strops.

All the way along I kept feeling the edge with my fingertips and it didn’t seem to be getting any smoother. Even the parts where I did raise a burr (at the tip and heel) still felt very coarse… They felt like they were around the 400 grit mark, certainly not 1k.

So I finished up anyway, removed it from the clamp and tried the fingernail catch test, which is my normal first test. The ends (heel and tip) caught ok but the middle did slide a bit, not a great result.

Arm hair shaving and cutting newspaper were the same – the middle was awful and the ends were a bit better but still not very good.

Now I was disappointed so I put the knife to one side and sharpened my Gyuto instead (Akifusa, 240mm) which is also 64 RC but this is PM steel instead of carbon steel. I did this at 10 degrees per side too (again 20 inclusive) and it sharpened up lovely, edge was great all along and felt smooth on the fingertips, passed all my normal sharpness tests. This cheered me up a bit… But not for long.

Feeling like I was ready for the challenge again I went back to the Teruyasu Fujiwara knife. Now I decided to go even lower on the angle at 8 degrees per side. I knew that reprofiling like that on a 65 RC knife would take a bit of effort to remove the metal so I decided to start with the 200 grit.

Went at it, again was taking ages to raise a burr… I dropped down to the 100 grit stones and after ages (again) had the same as before – the ends were getting a burr but the middle wasn’t.

At this point I noticed a chip in the edge near the heel. I pulled out the loupe and the edge looked like it was chipping in a few places so I stopped with the 100 stones immediately.

I went back up starting with 200, using the lightest pressure I possibly could, then 400 >> 600 >> 800 >> 1000, all using light pressure.

I kept feeling the edge with my fingertips and once again it was the same story – it felt pretty coarse, like it was a 400 grit finish no matter how far through the progression I was. I assume now this is probably down to chipping.

After 1000 I dropped the angle down to 12 degrees per side (24 inclusive) and then did some more light passes with the 1000 grit stones, then I backed off the angle a tiny bit more (maybe 0.5 degree per side) and did a few passes with the 1200 ceramics, then backed off the angle one last time (again 0.5 degree per side) and finished with a few light passes of the 1600 ceramics.

Then I removed the knife, obviously it didn’t pass any tests, but I don’t want to do any more today as I’ve probably done quite enough damage already.

So I’m pretty disappointed… Obviously I’ve been stupid by causing the chipping, that’s my fault for using coarse stones at low angles. I’m disappointed in myself but also a bit disappointed with the knife at the moment. My second attempt (8 degrees, 100 grit start) was stupid but my first attempt (10 degrees, 400 grit start) was within the range I really thought this knife would be able to handle.

So any advice appreciated. What do I need to do to bring this carbon steel (back) to life? How can I save this knife? The Akifusa is such a breeze to sharpen compared to the Fujiwara.

I’m a bit sad today, this is the first real problem I’ve had using the WE… I guess it had to happen sometime.

[Leo Barr]

Was the edge originally a convex edge ? I also think your angles are way too low the 10Ëš either side is not quite as low as the Shenogi which is probable more like 7Ëš but if the blade was a straight bevel I would have expected it to be more like 16Ëš.
This would probable account for your not getting to the edge check it with a loupe.
White carbon will be tough and i think that you just have not got to the edge.
I think you will find the shenogi will be a convex bevel which is best done on bench stones I think you will need to re do the lower part of the shenogi until you get rid of the additional angle you put in with the WE since I suspect you have added an additional shoulder then go back to the primary bevel the edge and try at least 15Ëš a side .
Looking at the photo from the web site the edge is a micro bevel so it should not be much wider than 1mm wide if yours now is then it will most definitely because you have lowered the angle too much.
Since the steel is brittle it should not be overly low and since it is a slicing knife there should be hardle a discernible shoulder from primary(micro bevel ) through to the shenogi.
If there is now substantial damage to the edge you really should remove that bevel by going very steep to just remove the worst then re-thin the shenogi ideally free hand convex to the edge then put a micro bevel on the edge using probable the 1k diamonds at 15/16Ëš.
I think the mistake you made was lowering the angle so much on the primary bevel had you kept t the same angle you probable could have started with the ceramics..
Some close up photos would help for further advice from either myself or others this sort of knife is really suited to 1k-3k & possible 5k Japanese bench stones it is not an entry level Japanese knife and the better they get the less suited tools like the WE are for them .

[Jamey Howard]

Cheers Leo. If the white carbon steel can’t handle the low angles without chipping then how are you meant to thin behind the edge? How can you do a 7-degree shenogi, or any kind of secondary bevel if it just chips once it gets thin?

I’m not too fussed about convex edges so I’m happy to have a plain V-edge, and I guess 15 degrees per side is decent, but I was just hoping that this steel would be able to take and hold a very fine edge and I’m disappointed I guess.

Cheers though.

Sent from my iPhone using Tapatalk

[Leo Barr]

Hopefully the primary edge will still be narrow and not have much of a shoulder it should be fine since it has not been sharpened much it will be very sharp at 15Ëš since the steel is very good its a good looking knife and serve you well for a long time.

[tcmeyer]

I don’t pretend to know anything about Japanese blades, but I think Leo’s right about the original edge being convex.

I’ve recently become painfully aware of the ability of the very coarse stones (read 100/200 diamonds) to chip edges. So now when I use them, I carefully watch the progress with a handheld microscope. A few passes with the stones and then slide the ‘scope slowly down the full length of the blade.

The very steep angles you’re using scare the willies out of me. I think that the steeper the angle and the harder the steel, the bigger the chunk that will be ripped out when you hit the very edge with a coarse grit. A ‘scope will show you what your stone is doing to the edge and at 200X power, the scratches from the coarse grits are really deep.

USB microscopes will clearly show you the detail you need to understand what the edge was to start with and where you are, relative to the edge as you sharpen. I have a Celestron handheld that is really easy to use and only costs about $76 plus shipping and will work on any PC built in the last 10-12 years. I use mine continuously, even with the finer stones, to watch for scratches and to monitor progress. Once I learned how to use it, it was so fast and easy that I almost never use my loupes anymore.

[Leo Barr]

This is a Mac Santoku I had to repair and here is a clip of the edge showing the convex bevel.

[Leo Barr]

Honyaki Nakiri Takagi Convex Edge

Not uploading vids right!
This is my Honyaki Nakiri Takagi with convex edge finished on Shapton Glass 16K There is some Camellia Oil on the blade in the vid filmed with a Veho

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[Jamey Howard]

Cheers guys… My natural follow-up question is this… If carbon steel can’t handle low angles then what steel can?

I want to find something I can put a very low angle on, and ideally I want it to be a very hard steel (above 63 RC really) so it will be able to hold it for as long as possible before needing to be sharpened again.

I thought there were loads of Japanese knives that were single-sides (IE bevel on one side, other side is flat) that had really steep angles, around 15-17 degrees inclusive? What are they made from, and how do they avoid chipping?

As for this knife, I’ll probably ‘destress’ the edge as described in the other thread by Cliff Stamp, just make one or two cuts into a stone to remove the metal at the edge, then sharpen at 15 degrees per side. But I’m not sure how sharp that will be, as I said it wasn’t super-sharp out of the box.

I’m not going to bother convexing it because I’ve never been massively impressed by convex edges to be honest.

[Leo Barr]

Single bevel knives such as Debas or Yanagi actually have high angles so a low angle for a chisel edged Japanese knife would be around 30Ëšso the same as a normal ground Japanese knife e.g. Globals 15Ëšor Shuns 16Ëš per side .
If you were say to use the knife slicing boneless tender meat on an end grain wooden board you may well be able to drop the angle somewhat but a really low angle is likely to chip on most things even then it depends on how much control you have with the blade in use if there is any twist in your action especially as the knife touches the board this to will snap off parts of the blade causing micro chips .
In reality it comes down to your knife skills , what you cut and on what; those are contributory factors that govern the angle of the bevel not only the Rockwell Hardness this is why a wham bam chef style is far more suited to European Chefs Knives with a Rockwell hardness in the mid 50’s which are more flexible and will take a lot more punishment in the kitchen.
This is possible why a good home cook ( who uses the knife slowly and is open to learning new knife skills) can probable use a Japanese knife successfully whereas a chef without sushi training will probable be chipping and breaking Japanese knives all the time since they abuse the knives no end not even using a cutting board all the time (I have seen a chef cutting a cake with a top of the range Shun on a china plate- no wonder the knife had rolls and chips in it when I was asked to sharpen it .

As for convex angles the Shenogi on a Japanese knife is I would say without exception a convex bevel even if the cutting bevel is not so this is why sharpening a Japanese knife on the WE is fine for the edge but thinning should rely be done on bench stones and is probable easier in reality.
It is not so bad if you were to sharpen a Shun (an entry level Japanese knife on the WE but the Shenogi or Uroashi sharpening requires bench stones and some of these knives are very expensive and would possible be considered as ruined if totally worked on a WE .
So if you don’t want to use bench stones stay away from the more traditional Japanese chisel edged knives or risk been billed for a repair by the owner.

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[Jamey Howard]

Cheers, but I didn’t ask for an appraisal of my knife skills 😉

I asked which steels (or which knives) can hold a low angle.

[Leo Barr]

Practically none below 15Ëšas said really fine angles are just not practical in general.
One of the toughest steels out is HAP 40 or ZP-189 & I think there is something else `clay sharpened nearly 70~RC .

Just to set the record straight the WE is a fantastic tool which is suited more to European style chef knives and folders especially when the knife is precious enough that any wandering above the cutting bevel would be considered unacceptable.
I use my WE for these sorts of knives but Japanese knives I do on Japanese bench stones this is what they are designed for especially once you get away from entry level.

Cheap knives I thin on a belt sander and finish the edge perhaps with one grit on the WE.
Currently there is no tool which is suited to all blades: yes you can convex an edge either on an Edge Pro or the Wicked Edge but in reality and a regular practice it is easiest on bench stones or even sand paper and a mouse pad. Since the method required on either the ~~EP or We requires a series of bevels which are then honed together by stropping I have done Globals this way starting at 10Ëš to the edge then working backwards so 15Ëš with the finishing stone -then 14-13-12-11 then stropping out the steps but on a bench stone this can be achieved in one sweep beginning at 10Ëš steepening towards the end of the stone at 15Ëš. This in reality is much quicker since it is the string of the angles that is the time consuming part on a guided rod design.

Once bench stones skills are perfected (for me about 30 blades doing 1or 2 a day over a month the secret is to do at least one knife a week on bench stones to stay in practice)it is not difficult to achieve the same level of sharpness as with the WE.

I don’t think anyone would question the sharpness of a true Samuri sword all sharpened traditionally.

[Jamey Howard]

Practically none below 15Ëšas said really fine angles are just not practical in general…

Well, I disagree with that, but obviously it does hinge on your own personal definition of “practical”.

What I will say is this… Almost every knife I have sharpened since I first got the WE has been below 15 degrees per side, even before I had the low angle adapter.

Most of the knives I have done have been between 12.5 – 14 degrees per side.

I much prefer them at this angle, they feel much sharper, much nicer to use and I’m careful with the way I use knives so they don’t get damaged too quickly.

Obviously they are going to need sharpening again sooner than if I used a flatter angle, but I don’t mind that… I bought the Wicked Edge because I enjoy sharpening, so I’m always happy to touch up knives to keep them working well, and I don’t mind doing it a little sooner in exchange for sharper knives.

Now a lot of my knives couldn’t handle any lower than the angles mentioned above but the few knives I have in good steels are ones I would expect to be able to go down to 10 degrees really. And like I said, my Akifusa Gyuto is/was fine with ten degrees per side and slices beautifully. But like I said that’s a PM steel, not a carbon steel.

So maybe the key is to use hard PM steels instead of hard carbon ones.

Sadly I don’t think anybody makes a kitchen knife in ZDP-189, do they? 🙂

[Blunt Cut]

Sure there are… examples of a few
* J.A. Henckel Cermax MC66 knives, e.g. TWIN Cermax MD67
* Search zdp-189 in CKTG site
* konosuke zdp 189

[Jamey Howard]

Sure there are… examples of a few
* J.A. Henckel Cermax MC66 knives, e.g. TWIN Cermax MD67
* Search zdp-189 in CKTG site
* konosuke zdp 189

Cool, I’ll have a look around then.

Expect a forum post from me in future entitled “My new ZDP-189 knife won’t sharpen at 6 degrees per side and now I’ve ruined it” 😉

[Leo Barr]

I have a HAP-40 laminated Santuku Hap – 40 can be hardened to Rockwell 68 . I believe it is around 64/65 in my particular knife.
It is a beautiful thin blade that did need a little sharpening when I got it and I did manage to micro chip the edge this was slicing and I thought I was been careful but I realised I was putting a tiny twist on the blade as it made contact with the board I could almost feel it catching and chipping so I steepened the angle a little and now it is fine . Even though the blade is laminated it is very thin and almost weightless and cuts through stuff almost as if it isn’t there it is second only to the Honyaki which is Blue Steel but forged.

My ZDP-189 is rated at 67.1
Clay either had or sharpened a steel that is rated above HAP-40
HAP -40 chefs knives are available; CKTG do one or two mine is from http://www.fine-tools.com/messerp.htm

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