JAPANESE KNIFE - Thinning 101
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- Опубліковано 13 січ 2021
- Hey folks, thanks for tuning in as always!
We've been meaning to do this video for quite some time but its finally here! We figured this would be a good video to add to our sharpening video lineup because every knife will need to be thinned at least a few times in its lifespan. If you were watching the first time sharpening video we posted last time this wont be something you need to worry about for a couple years as a home cook, but sooner and more frequently as a professional who is sharpening their knives regularly. Anyways, check it out and let us know what you think, cheers!
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Thanks for watching as always everybody! Jake and I had a great time making this video. Hope you guys like it and find it helpful!
Great stuff man. Can you do a thinning video for gyutos (tojiro dp for eg.) that don't have a primary bevel. Thanks and keep up the great content.
@@garrycation yeah a full flat knife... you either gotta give it a second bevel or you gotta think it al the way the spine... which is a beast to do without power tools on anything biggr than a paring knife. I can't even imagine doing that by hand on a freaking gyoto. That would take like 100 hours of grinding on a stone. I feel like it would be easier to just give it another bevel.
Thank you Gage. I have done this on my own with great results, but i always was unsure about my process and stones used. You went over many aspects of the process and cleared up all of my questions. Well put together video.
P.s. i live in portland next to the Portland knife house. You, and your products, remind me so much of the shop. I will be buying from you all soon to help during the hard times.
I wish I knew all of this before I started thinning my own knives. Best video about thinning I've seen so far! Good work.
Wow, thanks! Really glad you liked it! My first attempt at thinning was a nightmare as well, still have the knife took quite a few hours to fix the damage haha
Great job! Especially explaining the terms right up front. People sometimes refer to primary bevel in different ways.
Very useful information. I like the use of diagram as well as the actual sharpening process for visual aspects. I now have complete understanding of why I’m experiencing wedging and how to correct the problem.
Great video again. Thank you Gage and Jake. I really appreciate the point about the amount of pressure to use as well as the tip with masking tape and sandpaper.
Hey Grant, glad you liked it!
This works, it takes time & patience. You can also uses sand paper on a flat surface. The thinner the knife the harder to achieve a flat surface. Low spots will quickly form in the side you are grinding to match your finger placement on the top side.
Your knowledge is impressive . I’m working my way to that
Great video
If only I could get ride of my christmas weight gain like this!
Its hard work, thin out the collection and you may drop a couple ;D
Awesome! Thank you!
Thanks. Appreciate the taping idea tip
Great video guys! Very well explained and shown in the video. Way better than the other vids I've seen about that. Wish I had seen this before going at my Gyuto couple weeks back :-)
On the bright side, now you know how to fix it ;`0
Awesome
Great simple and very illustrative video .
Glad you liked it!
Did I miss you say what stone you used?
PS another great video
How do you thin a full flat ground knife or give it another bevel that can be thinned without thinning all the way to the spine. And whats the best equipment to do this in a reasonable way. Seems like you'd need some serious abrasives or power tools to do it reasonably. I feel like I'd need a 60 to 80 grit ceramic on a belt grinder.
will there be a video about creating convex on the blade and other skills about reprofiling a knife such as making it thinner behind the edge? I would like to learn more😁
This was interesting indeed! It might be instructive to demonstrate how to take a western 25 degree bevel to a 12-15 degree bevel for western knives. When I did this it made a world of difference in my cuts.
I've not tried this yet personally so I dont want to give misinformation. However with that being said in my experience most western knives I come across are full flat ground and don't really have a bevel to work upon and you'd have to set your own from scratch
What stones and grit do you start with?
I own a Kasumi Hammered 24 mm gyuto. This knife is made with a vg 10 core and an SUS stainless steel lamination and it has a beautiful Kasumi finish under the shinogi line. Is the thinning process going to destroy or damage the aesthetic image of my knife?
what grit of stone do you use for this ?
Gage, I currently use a kitayama 6000k stone for finishing my bevels. The finish is not bad, but on my protein knives i would like a mirror polished primary bevel. Do you have a stone that you recommend for mirror polishing primary bevels?
Also, would you happen to know which stones, or technique to use when i want a kasumi finish on the stainless clad, but want a mirror like polish on the primary steel?
Hey man! You have a couple options if you want to mirror! You could go up to an 8-10k if you wanted to add that to the collection but you could also use a few tricks as well. Depending on the steel 6k should get you pretty darn close to a mirror but one trick I've been using lately is to put my loaded strop on the table and go to town on it for 10-15 minutes on the bevels with a pretty firm pressure. Not quite repairing on an atoma or reprofiling on a 320 grit hard, but harder than I would be going on a 700-1k for sure. One of my scandi knives I just finished on a 2k and did that for 10-15 minutes and I couldn't believe the progress I had made! If you dont have a strop look for some super high grit polishing compounds, while it is attainable on stones I dont think its worth the work when you can use a compound or a buffing wheel.
Great video! Would you do a part 2 with narrow-bevel knives, and how to get rid of thinning scratches on the cladding?
Hey Sean, is it possible that your knife has a narrow bevel because it needs to be thinned? If not, I'm not sure I understand exactly what you mean but you can always send us a picture on instagram @sharp_knifeshop so I can get a better idea of what you mean! As for getting the scratches out thats an issue with either your hand pressure which is difficult to show in a video or possibly that youre not spending enough time on each stone to work out the scratches from the previous stone. If you start on a 320, go to a 700, 1k, 3k, 5k, by the time you get to the 5k it could take HOURS to remove the scratches from a 320 grit. You may have to start out again at a lower grit and take your time, if that doesn't work reach out to us and well help you figure it out!
@@SharpKnifeShop Oh sorry. I meant a knife like a Tojiro DP for example, or a Masamoto KS, where you don't have a wide blade road to flatten on.
Hey so it sounds like youre referring to a full flat grind. In that case you would need a jig to get a proper consistent bevel, but we reccommend just going for it, it wont be pretty, but we think a scratched up knife that cuts well is more important than a pretty knife that doesnt cut very well. So just go for it like weve suggested in this video but REALLY take your time when setting the angles for the new bevels. If you want to clean it up afterwards the tape and sand paper trick will really help smooth things out afterwards but you probably won't ever get a clean line by hand on a project like this.
Nice video ! I will try this when me knife need it ! Just for fun did you try a natural japanese sharpening stone for thinning a knife ?
We don't have any naturals at the shop, but my understanding is that they're usually pretty high grit equivalent. That being said when it comes to polishing the bevels after thinning thats where naturals shine the most! Maybe we can persuade Gage to bring a couple in to play with ;)
I used natural stone for regular sharpening and its crazy for the sharpening i think if you try you will have a lot of fun !
I think it would be useful to elaborate on a future video how you can define when thinning should happen. As you're dealing with new knives all the time, you have an easy comparison for when performance has deviated from a standard benchmark. If, however, you're using the same knife everyday, the very gradual change that accumulates as a degredation in cutting performance is often compensated for with a change in cutting technique or style, reducing perceptiblity. You'll often find the same with sharpening and people will be using blunt knifes yet claiming they're still sharp. Without an objective measure (such as a newspaper push cut), it's actually quite hard to know.
Thats a great point! I would argue that a paper test is pretty faulty as a knife can be pretty darn thick and have a razor sharp edge on it, while it may still fly through paper the real test is in harder produce like sweet potatoes and onions. One good way to check, is most Japanese knives are forged san mai, or three layer construction. When the edge of the blade grows ever closer to the cladding compared to where it was when you got it (can always reference product photography of new knives online) its time to thin! Another way to check is to see how big your secondary bevel has become, thicker knives will have a very high secondary bevel to bring a thicker stock to apex while maintaining a proper sharpening angle. The last way to check is just to look down the choil of the knife and look at the thickness that way and again compare it to a thinner knife you may already own, or reference pictures online of newer knives. If your knife has a bolster blocking your view of the choil, its probably german, and it probably needed to be thinned out of the box ;) Hope that helps!
@@SharpKnifeShop Sure, I agree. The push cut test point was related to sharpness, which I was using as an example of a comparable objective measure for something otherwise subjective, not the thinness of grind. I like your point about the outer layer of the san-mai being a guide. I had never considered that, and it's about as objective a measure as you can get. The checking the choil against other thin knives or a reference pic is where this is starting to get fuzzy though. For example, I spent an hour the other day doing my periodic thinning on my Yu Kurasaki Fujin petty. It's hollow grind aside, which is a PITA to work around without grinding off the Kurouchi, I took choil shots before and after, and the difference is TINY - yet there's a huge increase in cutting performance. In fact, the visual difference for periodic thinning (as opposed to major thinning jobs) is so tiny it's hard to see the difference at all, visually speaking. Yet, periodic thinning is what's needed to ensure consistent performance. In other words, the thinning is needed and makes a huge difference, yet there are minor visual differences, and a comparison of the choil is hardly very revealing until the problem is so huge that performance has already been suffering long-term. It may be worth considering for a future video. The outer San-Mai jacket creeping to the edge is a good objective measure. Maybe there are more! Or maybe you can highlight with choil shots the minor visual differences for the untrained eye to spot the warning signs on non-extreme cases? That would be really informative!
Thinning on Japanese knives should always happen. Knives can always be thinner. The good thing about these knives is the bevel they have that makes it easy to do, vs full flat ground like you see in most mass produced knives. Grind that bevel right down to the edge, then throw a microbevel on the edge if you want. That's how a Japanese knife should be imo
@@christophlawrence Yeah man, those over rated over priced Takfu hype knives with the hollow grinds are not really meant to be thinned. They are generally quite thin already and stay that way because of the hollow grinds. If you're gonna do that, then you'd want to do with a belt grinder or by hand or something otherwise you're gonna radically alter the knife.. changing the hollow grind into a V is going to remove a lot of material and the end result will be nothing like that you had before.
@@jeffhicks8428 “knives can always be thinner” I don’t think it’s a good idea to do with my Shibata R2 knives but I’ve thought about it. They are so thin that the maker mark could not be hammered in with a chisel and instead was etched in since the chisel would cut too far into the blade stock!
So are you sharpening the knife (primary bevel, i guess) at the same time or do you thin and then go back to sharpen? Well done video, love it!
The primary bevel is the wide grind that removes material from the full thickness of the blade (the primary bevel is what you thin). You would thin the primary bevel first, then go back and sharpen the secondary bevel (edge bevel, the grind that actually creates the edge). Hope that helps!
@@Umbro565 getting my bevels backwards😂. But thanks for answering the question!
Thats correct! However if you really wanted to, you could keep thinning until the secondary bevel is gone and you have a scandi grind. Ive done that with two of my knives and its a pain in the @$$ to sharpen everytime because you have to repolish the bevels (Okay, okay, you don't have to but how could you not?) and they cut like absolute monsters, lots of work though. But otherwise yes, you thin, and then go back to a normal sharpening routine.
On a related note, I'm curious on your approaches to sharpening knives with wide bevels. I'm not new to sharpening, but I recently got a knife with such a wide bevel, and so thin, that the bevel oif cutting edge is nearly invisible, if not invisible. I can feel the knife fall into place on the bevel behind the edge, and I wonder after sharpening that how else I sharpen the area between that and the cutting edge. From what I've read there are a few approaches to doing it, but it's hard to find actual demonstrations.
Im unsure by what you mean by sharpening the area between where the bevel starts and the actual cutting edge is, other than thinning when you ride the bevel on the stone?
@@SharpKnifeShop Ah. I've seen some people describe the process as hamaguri and say you first sharpen the area where you can see the kasumi finish/rest that bevel flat, then just ever slightly vary the pressure/angle to hit the core steel behind the edge, then you sharpen the edge with a very thin bevel. I've played with this a little on a new knife of mine and I found it quite difficult, but clearly something like this was done in the original creation because the finish on the core steel is a mirror polish, while behind it is the hazy kasumi finish, and then there's a nearly imperceptible bevel at the very cutting edge. Maintaining that contrast between the kasumi and the mirror on the core steel, and maintaining that cutting performance from this technique, is what I mean, I think.
Nevr heard about the thin grinded blades from SOLINGEN ("Solinger Dünnschliff", HRC 61), particularly from the manufacturer Robert Herder "Windmühlenmesser". with their ultra thin blade the necessity ti thin a blade is nearly obsolete...
So thining is basicaly a sharpening same way I sharpen scandi grinds. Lay it flat on primary edge and sharpen until the secondary edge is gone, or in this case almost gone.
Hi, does this process damage/scratch the Kuroichi finish of the knife?
Yes this process is removing the outside of the steel, which will take any kurouchi that was there with it. You should only be making contact where you intend the new bevel to sit when rising the shinogi line, and with some practice should be able to polish out the scratches with progressively finer stones until you hit a finish you're happy with! We should make a refinishing video soon!
After how many sharpenings should you thin the blade?
Thats a hard question to answer as theres a lot of variables involved like how thick the knife was to begin with, if its hollow or flat or convex, and how much steel was removed per sharpening! Much like when its time to sharpen, it goes by feel. When you start wedging into harder ingredients like sweet potatoes or carrots, or feel like no matter how often you sharpen you cant get a good edge, its time to thin!
I need a vid on thinning a knife without a primary bevel
Very informative video. Any tips for thinning a knife lacking a wide bevel (like a Victorinox)?
I was also wondering if you could make a video about sharpening the tip of the knife? No matter what I try the first 1/3 of the knife is never as sharp as the rest of it. This is especially the case with curvier profiles, like a gyuto. I've read that you're supposed to raise the angle slightly when sharpening the tip, but it doesn't seem to work for me.
Thats a great video idea! But heres a few pointers until then!
1 Use a smaller point of pressure and take your time with lots of passes before moving your fingers down to the next position. I like to overlay a little from 1st position to the next so there are no gaps in my edge Im setting.
2 Try to use a sweeping motion on your backstrokes at the end of each stone in the progression, take your time with these and don't just do two or three passes.
I didn't catch the grit of the stone. Can someone tell me it, please?
Hey in this video we started on a 320 and finished on a 700!
Do you have tips for thinning a knife with no shinogi line?
If its a full flat ground blade that needs thinning unless you have a proper wheel/belt sander with a jig you kind of just have to go for it an be realistic with your aesthetic expectations. You can thin them out and make them cut better but its very unlikely that you'll get a clean line even with the right equipment which is why theyre always polished off evenly. You can however use the tape trick to fake a line after you've thinned it if youre trying to clean it up a little bit!
@@SharpKnifeShop it would be cool to see a video on how you do that by hand. Most people I know use full flat ground blades and have no belt grinder. I personally know how to do it and have done it on maybe a dozen knives but most people don't know that this is even a possibility if you have no shinogi.
Can you just use polishing compound and /or a dremel tool at the end?
Also this will remove the damascus pattern? How do you bring it back!? ✊ 🤖 👍
Polishing compounds only work if the ground work has been done, otherwise it will polish but just highlight the underlying scratches that the coarser finishes do a better job to hide. Its not uncommon when polishing bevels to go back down a couple stones because you realized your ground work wasnt complete and its considerably faster than sticking it out on the stone youre on. Also NEVER touch a dremel to a knife, ever. Its too small a surface and you'll do more damage than polishing, or get a uneven and streaky polish best case scenario. Believe us, if there was an easy way to do it, we'd be doing it that way. EDIT
As for the damascus, to bring it back out the blade needs to be re-etched with ferric chloride and then buffed out to bring back the contrast, you need baking soda to neutralize it so it doesnt eat away at your sink so do your research before buying a bottle to play with!
2x72 grinder goes "Brrrrrrrrrrr"
What do you do when there is no defined primary edge or shinogi ? Same technique?
Yes, exactly! We actually just shot a new thinning video today on this subject. Same technique though basically.
Is that a King 300 stone?
In this video we start on the Cerax 320 (light blue) and finish it on the Cerax 700 (brick red)
I'll just buy a big block for my Faberware and make it a hot-rod.
Wait thats not me thats my family!
What if your thinning a mighty Mac with the scallops in the blade and you’ve worn your way to them at the heel
Not much you can do about that, and if I'm correct might macs are full flat grinds and without a jig theres really no nice way to go about it. It may be ugly, but at least it won't be too thick anymore
@@SharpKnifeShop yeah it’s a full flat so I’ve just been going at it the best I can then I sharpen at probably a 10 to 14 degree angle on each side but I feel maybe my results would be better if I raise the angle slightly
you dont even mention what grit stone to use, useless