# The concept of thinning



## DavidPF (Mar 16, 2021)

Has thinning (a large area of a knife, not just shoulders near the edge) always been a widespread practice, or is it a more recent thing? (For example 20, 50, or 100 years ago)

Superficially, it seems to me like there are suddenly a lot of knives being seen as too thick, when those same knives were apparently well received in the past; everyone just used them, and nobody thought they were too thick.

- Maybe thinning out knives has been standard practice forever, and I've just never encountered it - this would make sense, since I've always been "living under a rock" when it came to knives.

- Maybe nobody does it except the "high-performance racing knives" crowd, and suddenly I see more of them because I'm here.

- Maybe every Japanese person who owns a knife expects to thin it out before using it, and that's gradually spreading everywhere else.

- Maybe there really are a lot of poorly-designed knives (i.e. every single one that needs thinning), and it's about time they were corrected. (Somebody should tell the designers...)


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## ian (Mar 16, 2021)

Thinning is about maintenance and has presumably been around as long as people have been sharpening knives. If you sharpen the edge a bunch of times, the knife becomes too thick behind the edge and won't cut anymore, so it needs to be thinned.

If you're talking about thinning new knives right out of the box, that might be more peculiar to knife nuts and in particular people who romanticize certain makers that have zero quality control with respect to their grinds. Most reasonable people will just buy a knife that's already ground to suit their cutting style, but sometimes the hype surrounding a maker is so strong (or there are other qualities besides the grind that are important to the buyer) that it can seem like a good idea to buy a knife that you know you'll have to alter out of the box.


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## DavidPF (Mar 16, 2021)

That certainly works for me... the necessity one I already understood; the part about hype leading people to buy a knife that they didn't actually like or want, and then trying to make it into something else, makes sense. Thanks.


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## ian (Mar 16, 2021)

It’s not just because of hype, though. Sometimes you buy a knife and after using it a bit you realize it’s just not thin enough behind the edge for you. You can’t return it at that point and you know how to use stones, so you thin it. Not a big deal. Probably that’s been happening for ages too. You’re just only now starting to talk to people who know how to use stones.


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## Bigbbaillie (Mar 16, 2021)

Yea I think 99% of people aren't thinking about thinning their knives at all to be honest.
I don't think most home cooks use up the steel of a knife enough to ever warrant thinning. If they do it happens so gradually that they probably don't even notice a change in performance. Considering most of their knives are probably Victorinox or Farberware it's also probably more worth it to just buy a new knife for most people.
That may be a different story for home cooks on KKF but, uhh... yeah. I thin because my standards are set unrealistically high and I like using whetstones.

As you guys already kinda said though, thinning has probably existed as a practice since the first blade was made. I'm sure people even were practicing "thinning" on stone arrowheads and stuff way back too although it would have been a very different process.


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## RDalman (Mar 16, 2021)

I grew up with dull knives that where regularly thinned on coarse scythe-hone. That's how my mom had been taught by her dad. Maybe he could apex them but she sure can't  still they where pretty functional!


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## Bodine (Mar 16, 2021)

Ms Dalman has been thrown under the bus.


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## Barmoley (Mar 16, 2021)

Around here people get a new knife cut with it and think, "It is good, but I bet I can make it better" and to the stones it goes. Often times it is a perfectly good knife that 99.9% of the regular population would not even dream of. Same with most hobbies where an end user can realistically do something to the object of the hobby without totally ruining it. Some manage to improve knives, some ruin them or at least totally change the behavior from what the maker intended. Saw more than one Heiji with shoulders removed completely and convexed or convex ground knives turned into wide bevels. Not a problem if this is what the owner wants, but wouldn't necessarily blame the maker for making a faulty knife.


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## DavidPF (Mar 16, 2021)

RDalman said:


> still they where pretty functional!


In the end I guess there are two kinds of knives, functioning well enough and not functioning well enough. It's just tricky because the "grey area" in between seems to be where most of the world's knives live.


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## DavidPF (Mar 16, 2021)

Barmoley said:


> Not a problem if this is what the owner wants, but wouldn't necessarily blame the maker for making a faulty knife.


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## tcmx3 (Mar 16, 2021)

well, in theory if you sharpen the apex you also need to maintain the bevels to keep the same geometry.

as far as putting a knife that you just got out of a box on stones, I mean it depends. Ive seen some stuff with great finishes and even bevels to start that dont need any work and Ive seen not that. is that the maker's fault? well no, but then I also dont buy 800 dollar project knives; if I spend that kind of cash (and I have, more than once), I expect it to be good to go. apparently other folks dont see eye to eye with me but I also dont exactly see them in the sharpening section showing off their new jnats either.

Im not necessarily looking for thinner, btw, when I start, I want even and I want to see what kind of finish I will end up with after a knife has seen one of my uchis, suitas, etc. there's something really, really special about a proper natural stone kasumi IMO, and now I actually far more enjoy browsing stones than new knives.


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## DavidPF (Mar 16, 2021)

Internet sales and advertising have also made it much easier for more people to find and buy more and better sharpening equipment than they used to get locally.


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## GorillaGrunt (Mar 16, 2021)

Also traditional Japanese single bevels are sharpened across the whole wide bevel, so in effect the face geometry is the edge geometry. I’d imagine that the most straightforward way to adapt the production and maintenance techniques to a double bevel gyuto type knife would be to copy the bevel side to the other side as well and maintain accordingly, thinning as you sharpen.


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## Benuser (Mar 26, 2021)

I start any sharpening at the lowest possible angle, and raise the spine only little by little, until reaching the very edge. Any sharpening at a lower angle than used with the very edge is thinning. All to maintain the original geometry. 
Sharpeners using a grinder use to start at the spine, removing steel from the entire face. Has always been good practice. 
As most factory edges are poor I indeed start by thinning a knife OOTB as a part of a full sharpening.


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## chiffonodd (Mar 26, 2021)

ian said:


> . . . If you're talking about thinning new knives right out of the box, that might be more peculiar to knife nuts and in particular people who romanticize certain makers that have zero quality control with respect to their grinds . . .



TFTFTFTFTFFTFTFTFTFTFTFTF


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## big_adventure (Mar 27, 2021)

chiffonodd said:


> TFTFTFTFTFFTFTFTFTFTFTFTF



One man's QC is another man's WABI-SABI!


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## Benuser (Mar 27, 2021)

Back to basics. Why has thinning always been a part of proper knife maintenance? 
A spine is about 2-3.5mm thick. The edge 1 micron. With a good working knife, expect a thickness of 0.2mm above the edge, 0.5mm at 5mm from there, and around 1mm at 1cm above the edge. During its life, the blade will lose width. At some moment it will have lost 1cm. How do you think it will perform with a thickness of 1mm behind the edge?


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## Koop (Mar 29, 2021)

The concept of thinning sunk in for me when I started using a Spyderco Sharpmaker on my Spyderco pocket knives - it was an "aha" moment. Sal Glesser designed the Sharpmaker to set two angles - 15 degrees per side (DPS) and 20 DPS. The 15DPS he called a "Back bevel." You sharpened the knife with this angle first and could take it to a zero angle wire edge if you desired. But the idea with a pocket knife that could see rough use was to thin with the "Back bevel" then set the edge with a more durable micro-bevel at 20DPS.

I use a similar approach with my Japanese kitchen knives, but with more acute angles to take advantage of a keen edge that doesn't see much abuse in my home use.


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## adam92 (Mar 30, 2021)

First picture is out of the box of my Takamura R2, When its new, height around 46.5mm, now only 38mm
. next three picture is after around 4 years of heavy use in professional kitchen. I cut probably 80KG chicken in a week, tons of ingredient. Even though R2 steel, I still need to touch up my blade often to keep sharpness above 70%. 

I thinning & sharpening together every time to keep blade geometry, Even though like that my knife is not gonna cut like new knife any more as when the height become short, the blade become thick. I don't know what else I can do to make it like new blade. May took me endless hour to thinning the blade.


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## M1k3 (Mar 30, 2021)

adam92 said:


> View attachment 120602
> 
> View attachment 120603
> View attachment 120604
> ...


Thin higher up the blade. Place your fingers on the blade higher up. Right about where the shinogi/ridge is.


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## adam92 (Mar 30, 2021)

M1k3 said:


> Thin higher up the blade. Place your fingers on the blade higher up. Right about where the shinogi/ridge is.


That's what I do as you said


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## M1k3 (Mar 30, 2021)

adam92 said:


> That's what I do as you said


Then move your fingers higher.


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## ModRQC (Mar 30, 2021)

Thinning is fun - unless I don't feel like it then it's a PITA.

Perfect OOTB is boring - but it's so good to buy unbox and give pace to a knife that is. 

Once a knife is thinned, it becomes boring because I can't take it back yet. But I'm also glad I don't have to when I use it.

Think I love the Shi.Han so much because it is very workhorse and just needs thinning constantly. TF comes next because they can't grind properly. 

I don't entertain particular hype or love with any maker - I do with a knife. Then its maker gets my respect. 

It is hard to respect someone who looks at you disrespectfully from a cheap wannabe wooden box lined with disintegrating felt a shade of red from another era. So I respect the HT and equilibrium of the knife - not because I was told it was good, but because it has proven to be. 

The relation between thinning and hype discussed here - weird. You can pay a lot of money and get a knife that needs work OOTB. It's part of life.


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## adam92 (Apr 11, 2021)

After one hour thinking on Shapton glass 220, I still not satisfied with the thinness at all... fell like without power tool want to thin the knife like OOTB take forever, but I can't get the power tool due to limited place, maybe gonna try sandpaper 120 to try out


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## Benuser (Apr 11, 2021)

adam92 said:


> After one hour thinking on Shapton glass 220, I still not satisfied with the thinness at all... fell like without power tool want to thin the knife like OOTB take forever, but I can't get the power tool due to limited place, maybe gonna try sandpaper 120 to try out


Has the SG glazed meanwhile?
I'm asking because that happened to mine, who got turned into a smooth 500-grit with the corresponding scratch-pattern. Not willing to spend my Atoma 140 on it, I've got this


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## ModRQC (Apr 11, 2021)

adam92 said:


> After one hour thinking on Shapton glass 220, I still not satisfied with the thinness at all... fell like without power tool want to thin the knife like OOTB take forever, but I can't get the power tool due to limited place, maybe gonna try sandpaper 120 to try out



Thinning what and how exactly?


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## adam92 (Apr 11, 2021)

Benuser said:


> Has the SG glazed meanwhile?
> I'm asking because that happened to mine, who got turned into a smooth 500-grit with the corresponding scratch-pattern. Not willing to spend my Atoma 140 on it, I've got thisView attachment 122277


Luckily my one not glazed, & I try to use all surface of whetstone with different angle, try not to waste the stone.


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## adam92 (Apr 11, 2021)

ModRQC said:


> Thinning what and how exactly?


My Takamura, I try to thin like OOTB, seems impossible without power tools, gonna get the sandpaper to see how, don't want to waste my atoma as well.


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## M1k3 (Apr 11, 2021)

Shapton Pro 120 loves stainless cladding.


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## HumbleHomeCook (Apr 11, 2021)

Maybe a Work Sharp Ken Onion Edition??? It's essentially a small belt grinder.


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