Moritaka - Journey through hell

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ModRQC

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Part 1 – Origins

Once upon a time… a Moritaka.

Zip it, we know the story: it came with somewhat of an ill geometry (that’s a euphemism), but at least, without major faults to the grind.

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Other than the geometry though, I had a bit of another problem with it: Kurouchi fading each time it was washed, and I didn’t even use it often, wash it often, for it to get from black with somewhat gray patches to grayish with somewhat beige patches.

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I kind of liked the knife though, after some adjustments. Food separation/release, flat profile, slicing abilities and general work, balance for weight worked well. My thoughts: refining that geometry by taking off enough of the shoulders while trying to smooth out the beveling and slightly convex the V grind to the edge. The goal was to stop wedging – but try to hold on to the good behavior it provided with food separation/release.

The culminating point that set this journey in motion came when I used tape to cover the KU and started to work towards sanding off that thick shoulder. Knife was left with the tape on a couple of days before I had some time to be done with that first strike against the geometry… and obviously when I removed it the kurouchi was almost gone in patches where the adhesive did its worst.

A wool dishrag, and back of a scrubbing sponge, removed the rest of it within short order – a first step through the gates of hell.
 
Part 2 – Kurouchi Off…

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… leaving behind a yellowish shadow of its own vacuity. And let me assure you that this bare-naked iron cladding only knows of one kind of “patina”: yellow-brownish towards fast orangy rusty.

I was now delivered of a crappy KU, but only to land in a different kind of finishing problem: what could I do to this cladding to “calm” things down a bit?

Some suggestions of “bluing” but I wasn’t getting into that. Fact was that I thought, except for the yellowish trace, the knife looked a whole lot nicer with a plain somewhat on the rough blade like that. It suddenly looked overused and worn out – and it suited it. Ideally, this plain finish was my target, but one that would patina more “normally” – with a bit of luck, more beautifully too.

All this with the realization that my initial sanding didn’t remove much of this thick ungainly geometry – barely smoothed out the shoulders as it was - and I was, as right as rain, still having wedging problems.

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Part 3 – First thorough sanding: Cleaning

My equipment was very ill-adapted: drywall sandpaper #80 and #220 progression, blended with an energic session with the Naniwa rust eraser.
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Lest we forget to include some updated pictures of the grind and choil.
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By then I had decided that I would leave the better part of the shoulder on the left, non-cutting side, while smoothing it out more and convex it on the cutting side; an experiment to see if it would be enough to relieve some of the wedging while keeping intact the food separation/release virtues. So while sanding, I went to insist a fair bit more on the cutting side.

Testing with actual food revealed two things: it wasn’t enough to completely rule out the wedging problem, but it did good alleviating the worst of it; also, that sanding off the yellowish gunk with coarse paper didn’t do much in favor of a more stable patina – some of the yellowing comes back, the rest stains looking like s**t.

The geometry was interesting though if still nowhere thin enough or agreeable enough – the subtle shift in height between the shoulder on the left on the right seemed to relieve the cutting through dense food more than I expected without any steering of note. I didn’t think it would do quite that good seeing that it was generally about as thick as originally.

That made me realize that I had to pay more careful attention to the actual results of the sanding process – merely counting passes and trying to remain true to my idea did not do much in the way of assessing my real progress removing metal.

Also, that my idea was on its right way – to many extents almost imperceptibly so, but the effect was already palpable. A newcomer to this knife at this stage would have still thought “oh that knife is thick at the wrong place” but wouldn’t have experienced the worst of this problem as I did OOTB – for example, squeaking when halving an onion… Not me, the knife. Well, me too, but afterwards.
 
Part 4 – New encounter; new sanding equipment; 2nd sanding: Patina

It was around that time that I stumbled upon a thread from yet another one fellow member here that had modded the finish on a Moritaka. Went to contact him in private and asked his advice with a unit where the Kurouchi had been sanded off. A basis for his own work was explained to me: overdosed instant coffee overnight.

I first needed to polish the blade a bit more, so went to buy #400 and #800 automotive sandpaper – combined with another energic blending with the rust eraser I surmised it would suffice for a trial. I still went into some pain to create a differential scratch pattern… I didn’t know what etching would do, but if it could fix this it would just be nicer looking than I ever went for.

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In the end, the acid etching had one very obvious effect: the actual iron went a darker, matte grey. That and washing off the black deposit left on the blade pretty much erased what very little was left of my stupid pattern – total waste of time. Etching easy to see because Moritaka welds this to a stainless tang, here contrasting.

This operation without trying to modify the geometry all that much further, just lightly sanded a bit more on each side with coarser before going into blending, so we have a pretty much unchanged choil shot, and cutting experience.

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Part 5 – Passing-by trick; New sanding equipment (2); 3rd sanding: Geometry

In the next prep I had a more precise idea of what thinning was still needed, and could verify how the acid etching treatment had the blade behave – as per the picture it helped it go for a more regular “patina”. I still was not very enthusiastic about these results. My etching advisor did provide a last remark that perhaps I would get better results with finer polishing.
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Stumbled meanwhile on another KKF member’s post about the patina he imparted on a monosteel with a fairly simple and much quicker method using vinegar. Went with that while retaining the previous advice: bought some #1000 and #2000 automotive.

This time however, with still a slightly differential geometry in mind, I paid much more attention to the sanding process – verifying the geometry all along the blade, again and again until I was sure to have attained the point I thought would be ideal (well until testing it), and that the idea did prevail from choil to tip.
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It was a very long process and when it was over I went for a fast polishing work. I knew it would likely undergo at least one last sanding stage, and another forced patina, and another edge – paying more attention this time around, and knowing I was closing on the result I expected, didn’t mean that I was about to magically nail it on the spot.

It was the final experimental stage though, and the end result got clearer than ever before – and in cutting, was just about right for the knife.
 
Part 6 – Final polish: thinning and fine tuning

This time around it was a matter of blending the whole blade together, but keeping the geometry pretty much where it was. I did insist on the left side a bit more still to remove some more of the purposefully slightly more pronounced shoulder there, bringing in fact both sides pretty much equal but for a faint, still noticeable, chunkier ghost of the former shoulder on the left side that still imparts a slightly differential geometry

A big difference was a particular focus on the false wide bevel. To make sure I’d keep the idea right through sanding, the knife was first thinned a fair bit on Shapton Pro #320 until the bevel felt smoother – also obtaining a uniform and obvious scratch pattern I’d be able to focus on some more with the coarse sandpaper. Then I went for the #80 sandpaper general steel removal and #220 smoothing removal, there focusing on bringing faces and shoulders up with the thinning job as well as reworking the false bevel. Progress was followed closely this time again. Maniacally.

The final polish went as follow from there in a pretty straightforward and fast process: 400-800 (dry) – 1000 (dry and wet) – 2000 (dry and wet). Wet stages were a lighter rubbing until squeaking dry. Underside of leather belt crosswise for a good 5 minutes on each side.

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Gave the knife its best edge yet with a combination of SP2K, Kippington’s deburring technique, cork, and SP5K finish. Got fantastic cutting performance – beyond expectations from the final experimental stage.

It feels like a different knife, it feels like my knife, yet somehow it still feels like a Moritaka alright.
 
Special Moritaka Thanks

@bahamaroot – for wise words realigning some conceptual fundamentals in my mind

@Barclid – for advice on surface polishing

@Benuser – for anything and everything knife on my mind and tremendous help

@cheflivengood – for taking the time to share insight

@Dendrobatez and @preizzo – for no nonsense advice on correcting a problem

@esoo – for a “quicker delivery” process

@Matus – because a Moritaka can be loved

@milkbaby – for wise words that helped me find the landmark of this project
 
Annex 2 - A go at the handle

Seemed like the originally dullish plastic looks were sticking on this handle – it needed a slight reworking.

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I like the grainy feeling of #220 there – tangible on the smooth side, yet still grippy enough. Pics were reluctant to show such minimal work as I did there, but I tried to catch on not only the wood grain coming stronger, but the slight chamfering I gave to the ferrule and butt, and whole repolishing of the very butt where the wood had always felt rougher and unfinished – even with oil and wax. To give a good measure, I polished after sanding on the underside of my dedicated leather belt, oiled, removed excess and polished again with the belt, waxed, removed excess, and polished yet another time with the belt. The #220 grits still feels and adds to grip, but the whole thing is just blending enough into smooth.
 
Wow, talk about project knife! Kinda like a home reno...whatever time/materials you think you’ll need it’ll be triple by the end. That faulty KU is disappointing and it’s good you decided early on to get rid of it. Aesthetics aside it would have been shedding in food which is just unacceptable.

On the bright side what a learning experience! And that you were able to document the process so well for both yourself and everyone to reference is great. That looked to be a lot of work and now you have a knife you can be really proud of. Really enjoyed the read!
 
What fun. You are meticulous in your documentation; thanks for sharing. I will be interested to know what your use will be like in the future.

PS: I have given (to family) 4 moritaka's and I have 3 that I still use on rare occasion. I have one 240 dammy moritaka 240 Ktip that I go to frequently (nice long flat profile). I have yet to see an over grind issue.
 
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I'm going through a similar process with a since 2014 on Masamoto KK KU nakiri that had a horrible asymmetric grind and huge belly on one side. I've probably spent 10ish hours on the stone and still haven't fixed the asymmetry. The KU is all gone, but I want to remove all the pitting too, which requires at least 1mm of thinning.

At this point, i'm thinking of buying a belt sander or orbital sander to do the rough sanding. That or just crying.
 
I'm going through a similar process with a since 2014 on Masamoto KK KU nakiri that had a horrible asymmetric grind and huge belly on one side. I've probably spent 10ish hours on the stone and still haven't fixed the asymmetry. The KU is all gone, but I want to remove all the pitting too, which requires at least 1mm of thinning.

At this point, i'm thinking of buying a belt sander or orbital sander to do the rough sanding. That or just crying.

why do you want to fix the asymmetry?
 
Wow, that’s a lot of work, kudos for not giving up!

Most my iron clad has attractive blue patina, except my two Mazaki gyutos that give out poopy yellowish patina.

From the choil shot, the bevel is still pretty low, can’t make the behind edge thin enough unless you either go concave or raise the shinogi line much higher. It’ll be hard to compete with Toyama IMHO, but the food release should be better.
 
why do you want to fix the asymmetry?

The belly on one side was horrible. It would constantly wedge. It's still bad. I can't find the original photo but I'll try to take one of the current state.
 
This is the kind of thread that makes KKF so much fun. I really appreciate that you thought to begin documenting the process early enough so we could really see the progression and the challenges you had to address.
 
Thanks for documenting the process.

Can you estimate how many hours you have sunk into it?

Anyone who has not done a serious thinning and is wondering why good knives cost so much should read this. Anyone who has done a serious thinning already knows. It's mostly skilled labour that you are paying for. Sure, pro knifemakers have power tools, but they also have the skills to use them without wrecking the knife.
 
Thanks for the worklog and write-up! This is why i steer people away from moritakas unless they just really want to learn how to thin and alot about geometry.
 
the iron cladding seems to be really reactive, Yet another reason I'm not a Mortiaka fan.

great work ob the knife.
 
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