Sharing a bit of work I’ve done

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Just shutup n' grabbit!
KKF Supporting Member
Oct 16, 2019
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My usual axis being reviews, I’ve included in this report some specs and "insights" about both knives. I am mainly publishing about the first one because it’s a typical happenstance with J-knives; the second one because it was a dire job that I’m very happy with.

Without further ado…
First job: JCK CarboNext 210mm Gyuto “Lefty” (Ha!......)


JCK Original Kagayaki CarboNext Series Gyuto (180mm to 270mm, 4 sizes)

The above link obviously that of the source of this knife, and I provide it as to verify two things if the reader wishes to: first thing is the choil shot, which shows what I’d call an almost perfectly symmetrical V-grind with quite an asymmetrical edge; second thing is specs, as to show that this unit here represents them quite closely – and that in making it symmetrical, no significant blade width was lost.

My customer is left-handed and ordered the lefty version. His can only seldom represent the original choil shot from the link (in reverse) because he honed the knife to health with a ceramic rod for more than a year using about the same angle on both sides.


If you ask me though, this is no real error, as there is very little of the asymmetrical sharpening here that makes much sense at all. Also made my work somewhat easier while insuring I wouldn’t sacrifice much blade width from there. A Masahiro VC honed for months symmetrically would still be a heavily asymmetrical grind without much hope for symmetry… before turning it into a Suji-gyuto.

The blade is quite pliable, a bit too much to my liking. The first thing I had to do was indeed to straighten it, as it was noticeably crooked out of handle, and quite some more at the tip.


Grid choil shot

We’ll see later on that the left side was ground flatter than the right side, as is often the case with J-knives, which goes to show this unit was not especially cared for towards going for a lefty grind. It is run-of-the-mill work with their usual righty grind. It was just sharpened lefty – quite the fake and rather useless asymmetrical proposition to me either way.

When assessing what work I had to do, I simply told my customer I would thin it to a rather symmetrical, slightly convexed edge. I did pay heed to him being a lefty though, even attacking each new stone at each new step from the left side first, just to get the right (left?!) tone… And trying to avoid my righty bias as well. What I was aiming was something resembling my Konosuke HD2 grind – that’s no afterthought but exactly what I proposed my customer beforehand, showing him mine’s choil:


Behind the edge specs weren’t bad at all as it was for the CarboNext, it was mostly maintenance thinning. Didn’t know if that steel was tough, nor much of how my customer uses it, so I had no intention to get it super thin.


All that said…


Thinned using Cerax 700, seeking maximum control on little steel removal while convexing, and maximum mud coverage over the grind, going full kasumi. A fair deal of work was carried to the spine and the choil, but also to the shaping of the bolster, where the taper to neck left a rather sharp angle where the user was liable to grip. There I paid particular attention to the left side again.


A bit of measurements, showing +/- 1 gram of steel removed, slightly thinner grind overall and more than good enough behind the edge thickness, and still 43mm tall.


Choil shot – unsharpened


Grid choil shot - unsharpened
Now, about “asymmetry”, here is how the kasumi took hold on the right face…


… and how it took hold on the left face…


…with a typical “overgrind” at the center from a much flatter grind.

Kasumi was: Cerax #700, Imanishi #1200, Ouka.

Decided to do a little bit of experimentation on this undisclosed semi-SS steel with regards to corrosion resistance…


Basically took an hour and a half of soaking into pure vinegar, blade heated beforehand with boiled water, where I took it out at each 30 minutes to look at things, letting air affect it and reheating with boiled water each time. Mostly, the first half-hour did next to nothing, the second one incurred some real noticeable darkening, and only after the third one did it finally take on some colors.


Then I had another go at Ouka hoping to refine left side Kasumi a bit… without much success.



Final edge, as provided by SP5K – my customer demanded it as he had bought one of my knives finished on it and liked the edge.

The keen eye will guess the SP1K-2K-5K boxes in reflexions...

Didn’t charge ANY of the kasumi work: just thought it was still the fastest way to blend the thinning scratches, and I always like a reason for another polishing test project. Customer paid for thinning and sharpening job only.


Oiled over and left to simmer...


Final choil – sharpened

Pretty close to Konosuke target, considering that this unit has a noticeably thicker BTE at heel, which I preserved for obvious reasons, and that it was reproducing the grind I had at heart since bringing it too thin was not a liable option. BTW this steel sharpens quite painlessly, whatever it is.


Target: Konosuke HD2

In testing the knife glided through food effortlessly, and I found food release adequate for the grind. I tested with my left hand and my right hand.

My customer’s final comment on my work:

“Small update after a few preps done… One of the ultimate tests I consider for my blades is to trim a brisket. You need to remove the fat that won’t melt upon cooking as well as the silverskin. The difficulty being that the fat has a tendency to be somewhat elastic and slippy, making the knife skid.

Verdict: wow – what an experience! The edge is so good that I only need but to follow with it. Silverskin is a breeze. Effortless cutting with your edge. I can even slice real thin layers of fat easily, so acutely it goes into it.

I’ll be back shortly with Project #2…”
Second job: Ryusen Bonten 180mm Gyuto

Story: the knife was lent to some folks for a while, and among many abuses where we could suspect a few dishwasher runs and some trials at sharpening it with quite ill instruments perhaps and/or skills for sure, we know for a fact that it was at one point used as a hammer too. Apparently, the party responsible for this didn’t find the real hammer that time around. It figures… I guess.

When my customer last visited them, he took the knife back upon seeing what state it ended up in, and started pondering about where to send it for professional restoration. It’s my work on his CarboNext that rather convinced him he should leave it into my care and see.

Here are specs and a recap in of the various damages I was hired to repair…


Well, if one thing, it didn’t need much thinning… amazingly enough it’s like it never really was used to cut so much, but rather readily abused in various other ways not involving the edge. Obviously it was dull as hell, but the edge could have been another kind of moonscape hell all of itself, seeing what happened to the rest.




Slightly tipped


Right side…


… a total mess.


Left side was somehow in better shape…


… but still no walk in the park.


Bolster not pretty, rivets in a similar disarray, and Micarta showing critical signs…


… of severe trauma where one can suspect dishwasher, but I also suspect steel wool or something…


… yet I can’t show how hopelessly dead and displeasingly harsh it felt in hand.

He had sent me a few pics… but that’s about when I fully grasped how dumb I was standing with my DIY ways and kitchen countertop workspace and trying to keep costs for labor low… This wasn’t going to be worth what kind of money I could charge that was reasonable. On the bright side, I was getting paid to look about and try my first Ryusen – well, try after I’d be done with it, so I’d never truly know. Still, I don’t know that I’d have agreed to this, and I’m sure I wouldn’t have done so much, if that had been your standard low end J-knife. We can factor sheer curiosity within the folly of my presumptions.
After three consecutive evenings of work, and a sharpening session the next morning (day off), representing about 10 hours of work, the knife was ready and I managed my effects with two pics as I reported back to my customer.


But warned him that it wouldn’t be as close to perfect as it looked out of these… I was of a mind to not overdo it from the start: I wanted some battle scars on there. I mean, a knife is a story, and this one that of a faithful, enduring warrior that’d just gotten free from death camp… or a testament to how much J-knives can really endure despite their toted fragility. Then again, the knife was pretty much untreatable that way: battle scars were not scarce, nor so readily willing to be erased – if I was to keep it true to specs/grind.


First night was dedicated to filing away the most of the dents in the spine and re-rounding it. You can still see faint traces of the deepest dents, but wouldn’t feel them much with your fingers. Then I went to determine with a few tests what grit of sandpaper was best to start a blade polish to cover the worse of those scratches. Additionally, a first effort at smoothing the choil and sanding the bolster a bit to cover the gibberish scratching with 180 grits. From there I could just take all of the detailing up to the next few grits of sandpaper applied to the blade polish.


Second night was dedicated to the full polish of the blade, and etching. Sandpaper progression was 80 – 180 – 320 to cover things up, then 400 – 800 - 1000 to get it to a mirror migaki. Spine was left at a quick 800 grits, choil and bolster went up 1200 and 3000 grits sandpads. Then some metal polish buffing overall. I don’t use powerful etching agents, just vinegar. I couldn’t get anything to pop out much: it just went into making it a bit more readily noticeable. A final cleaning using #3000 sandpad with a tad of mineral oil and no pressure at all. Left the handle to sink some oil in too.


Third night was consecrated to the handle indeed. I used a progression of sandpads #320 – 800 – 1200, then a slight retexturing at #400 again for grips, and a final gloss with #3000 sandpad. Mineral oil was copiously applied and left to soak in before each sanding, making sure that I was also having some further penetration as I was progressing; left to sit with a good coat of wax overnight. A final buffing with microfiber clothe on the next morning before sharpening, then a good cleaning when sharpening was done with.


It also resisted a few further dips and washes and rubbing in warm soapy water without seemingly wanting to go back all dry and rough, so pretty solid work there.



Any damage to the edge wasn’t extensive: I cut a new edge bevel at a tad more acute angle, enough to slowly clear off of the messed up apex towards stability. Started with SP1K: didn’t own SG500 yet back then and had long sold NP400, didn’t want to use something coarser or muddy. Just needed a stone fast enough/hard enough that I was fully in control. I still basically spent 15 minutes in cutting that bevel. Had a good time there though, SP1K is not a timid stone and when you know it it’s just so precise; then SP2K cleanup and Ouka/Morihei 4K refinement/deburring went in a blur.


That’s how good Ryusen’s HT is – smooth deburring and refining I was basically doing Carbon level flow. I think it makes a pretty nice knife. Liked the profile, grind is good, and their Damascus is neat (even more when properly popping), with one thing of note with this one: the tang wasn’t ground perfectly level with the scales, leaving a bit of a rough handling there. My customer talked about it as an OOTB condition, and I did smooth it out some with the whole handle work until it didn’t register so much.

Final edge for this one was Morihei 4K. That stone blends well with good hard SS and semi SS steels for a very lively fine edge. I like it after Ouka then, they tend to balance these edges very well.


My customer’s first reaction to this one was sending me a picture of a cut he incurred soon after getting it back. Blade took its blood sacrifice. I’m sort of surprised it didn’t take it on me: I really gave love and care for authenticity with this one (but the Dammy pop), and where there’s love for a knife, there’s blood to be shed by that heart. But then again… a faithful warrior. Waited diligently to cut its master instead. Good lad.


Then a good while later he took some more time to provide feedback – it was a quite longer one than with the CarboNext so here’s the essential:

“From the start, I knew the edge on the Ryusen was much sharper than the factory job on my Z-Kramer, not even comparable. Mind you, the Kramer was sharp, borderline scary, but your edge on the Ryusen was scaarryy…”

“I realized in use that the blade was not exactly going where I thought it should, but just where it ought to go, naturally and effortlessly. (…) The feeling of being guided and accompanied not as a master of a tool, but as an equal to it, is weird but fun.”

“I don’t know if you’re into RPG games like Dungeons and Dragons for example but in that universe, there are
intelligent blades/swords, with their own conscience and personality. The Ryusen feels like it has a will of its own and knows to find, without much of my input, the most efficient cutting trajectory – requiring no effort.”

I didn’t know much what to think about that but warned him that he could be experiencing some steering from a somewhat righty inclined convexity to the blade and to get back at me if he thought there was a problem. He didn’t so I figure it works for him. Also, I seemed to gather that his Kramer had a better OOTB edge perhaps than what I gave his CarboNext - or it was his insistence with getting the latter back with a SP5K edge. Still, point taken – I should firmly refuse to compromise my work with such demands on rather unknown or unappropriated steel. Mind you, since then I sold SP5K so… that’s that.

Now here’s a whole lot more pics and necessary comments – says who defines necessity here.


Hairs flew each side the cutting area and the other half on the countertop as well… is that hair popping sharp I don’t really know I don’t tend to test this way…


…on just that little spot of not so hairy forearm. Smooth shave – my skin there always looks this bad and irritated at best (eczema), as the surrounding areas prominently show, but I didn’t even feel irritation.


Kanji and Damascus…


Left side – yours, truly!


Ok so here’s the smoothed ch… OH! That’s from where all these things come from?


Edge – left side – also prominently showcasing the ugly seam between blade and bolster polish. I like bolsters for that: easy place for a seam so won’t tend to show first looks much.


Thin enough… Sharp enough…


Good enough!