Sharpening Confusion!

[Devious Rhesus]

Howdy all!

I'm on a quest to get my ZDP-189 gyuto to "scary sharp" levels. So far, i've achieved "slice a receipt cleanly," but not rolling papers or arm shaving. Therefore, I have some questions!

My sharpening equipment consists of Naniwa Professional 1k, 3k, and a solid leather strop - One side suede that I use green crayon style honing compound on (from sharpeningsupplies.com), and the other hard leather. I will sharpen on 1k, deburr by drawing through cardboard, strop with edge trailing on the 3k about 30x per side, then 30 passes on suede w/ compound, and 30 on hard leather - All at the same ~10 dps.

Now, I read the eBook "Knife Deburring 6th Edition" last night (from knifegrinders.com.au), and it's got me asking questions about getting to the next level...

Should I be stropping on a higher grit stone before the leather, and if so what grit? Can I go straight from 1k to this higher grit, or should I stair step?
What "grit" is that green compound anyways?
They mentioned in the book that deburring on edge wood/cardboard/felt tears the burr away and while it does remove the burr, does so violently and is not ideal. Is this the general wisdom, that I should be removing by edge trailing on finer stones? They said to do so at equal angle for high hardness steels, and slightly higher DPS for softer (generalization).
There was a section about how using traditional stones on high-vanadium steels was less effective, because it abrades the steel surrounding the vanadium, and leaves the vanadium proud of the surface - Where it will tear away and leave the edge rougher and weaker - And instead you should use diamond, which can also abrade the vanadium. ZDP-189 seems to have very low vanadium content, but its hard to find a definitive answer - is that accurate? And also, are other carbides also hard to abrade with traditional stones, and is it good practice to upgrade to diamond stones for most high-end steels? My other knives are VG-Max, which does have 3% vanadium, so there's that...

Who knew there was so much nuance to scraping metal off your knives! Thanks in advance!

 

[HumbleHomeCook]

I say we back up a bit...

What is the opposite of de-burring? Leaving a burr right? What does a burr do? It will often feel very sharp but dull within a cut or two. If you had burr remnants, I'd think you could shave arm hair to start. Maybe not, but a thought.

Also, you should be able to shave off lower grits. We can't grit our way into sharpness. The higher grits refine the work we do on the lower grits. I don't know for sure of course but to me it sounds like you're over stropping and possibly rounding the edge and/or polishing the edge beyond having enough tooth to catch your arm hair. Arm hair can be a tricky gauge as people vary so much.

I generally use receipts and paper towel these days. If I can slice paper towel, even if it's a little ragged, the knife is good to go for the kitchen.

ZDP-189 has basically zero vanadium but it has a boatload of chromium so it is quite hard:
http://www.zknives.com/knives/steels/steelgraph.php?nm=ZDP-189&ni=410&hrn=1&gm=0
Just my thoughts.

 

[Kawa]

As it might sounds counter-intuitive, try edge leading for deburring.

Also don't do 30 strokes per side, not for deburring, not for stropping. Its too much.

If you need 30 strokes to remove the burr, you haven't lowered pressure/ flipped enough during sharpening. The burr should be already almost non-existent before you do a few final (edge leading) deburring strokes.
Then you remove the final remnants on a strop, like 4-6 strokes per side.

When doing 30 stropping strokes per side, you edge will probably be rounded off too much.

 

[Kawa]

The green compound 'should' be chromium oxide, fairly coarse (nothing wrong with that).

But nowadays, they can add any color to the crayon, so to be honest, you don't know what youve got, unless the store gives some specs

 

[Delat]

My sharpening equipment consists of Naniwa Professional 1k, 3k, and a solid leather strop - One side suede that I use green crayon style honing compound on (from sharpeningsupplies.com), and the other hard leather. I will sharpen on 1k, deburr by drawing through cardboard, strop with edge trailing on the 3k about 30x per side, then 30 passes on suede w/ compound, and 30 on hard leather - All at the same ~10 dps.

If your “stropping” consists of 90 passes per side total post-sharpening, then it’s gone way past stropping. It sounds like you’re actually trying to further refine the edge, but you’ve introduced a ton of room for error - basically rounding the edge. Also if you’re doing 30 edge-trailing passes on a 3k stone… well that’s sharpening and you’re probably creating another burr, not stropping.

As others have said, your edge is established with your first stone and everything after that is just refinement. Stropping is just removal of the final burr and its remnants.

So try this - instead of 30 edge-trailing on the 3k, do 3-4 super light edge-leading. Then 10-12 edge-trailing on the suede or leather, not both. If you established a solid edge with your 1k, this should be all you need to clean it up. As a side note, I understand ZDP is quite hard and it’s also possible you might not be using the right stones for the task but I wouldn’t know anything about it.

I’m no paragon of technique, but here’s a video of me doing a refresh of a very slightly worn edge on a strop (1 micron diamon loaded buffalo). This is the same stropping I do after sharpening. Looks like I do about 10-12 strokes per side. You can see just that little bit gets the edge back to cutting rolled paper (which is fun to shoot for as a benchmark but not really noticeably different in actual use).

 

[cotedupy]

The really big secret here, the one that no one ever tells you, is that for the majority of kitchen knife applications: lower grit finishes are sharper.* Because sharpness depends as much on what you're cutting, as what you're cutting it with.

It's a cliche to say it, but concentrate on proper edge-leading deburring on your final stone, and strop on paper or cardboard. Nailing that is everything.

I was sharpening some of my family's knives today pre-Christmas. This is horrid modern stainless (eurghh), with a horrid fingerguard (EURGHH), and a thick Western grind. Shapton Glass 500, stropped on an old newspaper:

* Within reason!

 

[salparadise]

concentrate on proper edge-leading deburring on your final stone, and strop on paper or cardboard. Nailing that is everything.

I was sharpening some of my family's knives today pre-Christmas. This is horrid modern stainless (eurghh), with a horrid fingerguard (EURGHH), and a thick Western grind. Shapton Glass 500, stropped on an old newspaper:

Yea, I read a stropping thread recently and it was all about leather and diamond paste— nobody even mentioned newspaper. I love it. It’s magic.

I sharpened my daughter’s knife, and her roommate’s, today. Two of the dullest knives I’ve ever had to sharpen. My daughters is okay, a Masamoto. But the other on was a Target special. I put both to the DMT bench sharpener to remove metal fast and form an edge, then SG 500 and finally newspaper stropping.

Daughter is a foodie, and she’s been here cooking for me for a week now, using my carbon knives. She realizes she needs a new knife strategy going forward. Mushroom Bourguignon tonight!

Merry Christmas/Happy Holidays to everyone!

 

[coxhaus]

Mushroom Bourguignon tonight sounds wonderful. Enjoy and Merry Christmas.

 

[jedy617]

So I have owned a few ZDP knives. It was specifically made with chromium carbides so it could be used with alox stones vs diamond. You don't NEED diamond, but they are faster cutting in my experience. my favorite edge was off a chosera 3k. Going from 1-3k is a fine jump imo. You might want to try just stropping on your 3k stone, you might be polishing your microbevel a bit too much with the strop.

 

[Blank Blades.]

When doing any sharpening i do. I try my best if i can to cut down any extra steps. Because the more passes i do on a stone the more chance i have of adding excess convexity which in the end will decrease the sharpness of my final results. Since no matter how good a person is at sharpening free hand, there is SOME variation in angle that will inevitably happen, and thats fine, but keeping it to a minimum is key for this.

I find once a burr is achieved on the final stone im using. I start doing alternating strokes (edge trailing, or edge leading when using very light pressure i havent found a giant difference between the results left by either) to remove as much of the burr as you can on the stone if not all. Then move to your strop. Once your on the strop its better to risk being too acute than too obtuse of an angle because most stropping materials do have some give to them. You dont want to convex your edge radius even more.

So once youre stropping do alternating passes. At most if you arent strictly doing alternating passes do 2 or 3 each side, and switch sides. But i recommend ending doing alternating strokes either way.

Also the stone progression i use itself. I keep the same principle of trying to minimize my time on each stone in mind, and the fewest possible stones. So ill do decently sized jumps in grit. As long as it doesnt take too long to remove the previous scratches.

 

[gc0220]

I'm big on ZDP and freehand sharpening and have my ZDP blades literally catching and cutting free hanging hairs sharp like straight razors. If that impresses you, it shouldn't. It's not impressive, most people just never put in the time to learn. It's not difficult. The benefit of ZDP which makes it so ingeniously designed is the fact that it only contains chromium carbides. This means that you can indeed sharpen this stuff just fine with regular stones. For the given level of performance you're going to get it's by far the easiest to sharpen steel out there. Any other steel that performs anywhere in the same ballpark as ZDP is just exponentially more of a pain in the ass to sharpen. And that's the genius of it. Some people might say "well it's brittle compared to 3V" or whatever, but hey, don't use it in a outdoor knife to baton wood. It's not made for that. It's made for kitchen knives, to cut soft ingredients on a forgiving surface, not abused, and thus in a kitchen knife it's more than tough enough. Certain a hell of lot tougher than white or blue steel and usually harder. I've used and tested it extensively and never got close to edge failure in anything even approaching normal use. All that said, in my experience it's a pleasure to sharpen. It wants to get sharp. It's not difficult at all. This stuff isn't fighting you to take super keen fine edges. It's not hard to debur at all either, very easy. As long as you understand going in that the abrasion resistance is much higher than what you're used to.

The only chosera you listed that I'd bother with is the 1k and even then it's not a preferred stone for me on this application.

Anyway unless you have your technique dialed in I might just advise you to pass on free handing the stuff. If you want to freehand it, how dull are these knives? Try something like a 400 grit chosera if that's the stones you got. Otherwise I use Shapton glass and it works well, even going into higher grits (up to 8k on SG no problem, never bothered more than 3k on a chosera which was very slow), but with steels like this you want to use lower grits than you might think or otherwise use. ZDP is a steel that takes a long time to dull and I generally don't let it get there in the first place.

I know a lot of people think choseras are these super crazy fast cutting stones from youtube videos but it's not the case. They do cut well, especially for more common steels used in Japanese cutlery, but they're also fairly gentle and generally polish higher than they're rated. They're nothing like say a Shapton Glass stone, which again from youtube some people are convinced the Choseras cut just as fast or even faster. Not ZDP they don't. I don't think they do at all, not even close really. SG 4K cuts faster than 1k Chosera. You want a faster cutting stone that isn't a shapton glass or a diamond stone, then use a soaker with high pressure. If you muscle a good soaking stone that thing will cut faster than you can believe. Choseras are thirsty and supposed to "feel like" or have the "vibe of" a soaker but they are not soakers. In fact soaking them wrecks them so don't do it.


If you're starting from scratch, I'd say use a 500 grit shapton glass stone to sharpen the steel. I hope you're not convinced to "use the weight of the blade" or some nonsense when you're starting out. Muscle that ****. But don't lose paitence and jump to diamond plate. It's not that hard. Anyway, 500 grit glass, Then use something like a 5k diamond compound on wood to refine it. You could take it further with some 1 micron if you wanted. That's all you'd need to get it to "get started" down this road. I'm sure a 400 or 600 grit chosera would probably work fine too.

 

[Blank Blades.]

I'm big on ZDP and freehand sharpening and have my ZDP blades literally catching and cutting free hanging hairs sharp like straight razors. If that impresses you, it shouldn't. It's not impressive, most people just never put in the time to learn. It's not difficult. The benefit of ZDP which makes it so ingeniously designed is the fact that it only contains chromium carbides. This means that you can indeed sharpen this stuff just fine with regular stones. For the given level of performance you're going to get it's by far the easiest to sharpen steel out there. Any other steel that performs anywhere in the same ballpark as ZDP is just exponentially more of a pain in the ass to sharpen. And that's the genius of it. Some people might say "well it's brittle compared to 3V" or whatever, but hey, don't use it in a outdoor knife to baton wood. It's not made for that. It's made for kitchen knives, to cut soft ingredients on a forgiving surface, not abused, and thus in a kitchen knife it's more than tough enough. Certain a hell of lot tougher than white or blue steel and usually harder. I've used and tested it extensively and never got close to edge failure in anything even approaching normal use. All that said, in my experience it's a pleasure to sharpen. It wants to get sharp. It's not difficult at all. This stuff isn't fighting you to take super keen fine edges. It's not hard to debur at all either, very easy. As long as you understand going in that the abrasion resistance is much higher than what you're used to.

The only chosera you listed that I'd bother with is the 1k and even then it's not a preferred stone for me on this application.

Anyway unless you have your technique dialed in I might just advise you to pass on free handing the stuff. If you want to freehand it, how dull are these knives? Try something like a 400 grit chosera if that's the stones you got. Otherwise I use Shapton glass and it works well, even going into higher grits (up to 8k on SG no problem, never bothered more than 3k on a chosera which was very slow), but with steels like this you want to use lower grits than you might think or otherwise use. ZDP is a steel that takes a long time to dull and I generally don't let it get there in the first place.

I know a lot of people think choseras are these super crazy fast cutting stones from youtube videos but it's not the case. They do cut well, especially for more common steels used in Japanese cutlery, but they're also fairly gentle and generally polish higher than they're rated. They're nothing like say a Shapton Glass stone, which again from youtube some people are convinced the Choseras cut just as fast or even faster. Not ZDP they don't. I don't think they do at all, not even close really. SG 4K cuts faster than 1k Chosera. You want a faster cutting stone that isn't a shapton glass or a diamond stone, then use a soaker with high pressure. If you muscle a good soaking stone that thing will cut faster than you can believe. Choseras are thirsty and supposed to "feel like" or have the "vibe of" a soaker but they are not soakers. In fact soaking them wrecks them so don't do it.


If you're starting from scratch, I'd say use a 500 grit shapton glass stone to sharpen the steel. I hope you're not convinced to "use the weight of the blade" or some nonsense when you're starting out. Muscle that ****. But don't lose paitence and jump to diamond plate. It's not that hard. Anyway, 500 grit glass, Then use something like a 5k diamond compound on wood to refine it. You could take it further with some 1 micron if you wanted. That's all you'd need to get it to "get started" down this road. I'm sure a 400 or 600 grit chosera would probably work fine too.

Its not just brittle compared to 3v, its brittle compared to just about everything except rex 121, and maxamet. Theres just no way around it having low toughness having a 30% carbide volume. Maybe it can be tougher than some makers super blue, because theyre literally trying to judge the temperature by eye site rather than using controlled temperature, which means any given knife they left in a bit too long could suffer from problems with plate martensite. But generally speaking it shouldnt be.

Its still a fine steel for a kitchen knife like you said though.

 

[Benuser]

Howdy all!

I'm on a quest to get my ZDP-189 gyuto to "scary sharp" levels. So far, i've achieved "slice a receipt cleanly," but not rolling papers or arm shaving. Therefore, I have some questions!

My sharpening equipment consists of Naniwa Professional 1k, 3k, and a solid leather strop - One side suede that I use green crayon style honing compound on (from sharpeningsupplies.com), and the other hard leather. I will sharpen on 1k, deburr by drawing through cardboard, strop with edge trailing on the 3k about 30x per side, then 30 passes on suede w/ compound, and 30 on hard leather - All at the same ~10 dps.

Now, I read the eBook "Knife Deburring 6th Edition" last night (from knifegrinders.com.au), and it's got me asking questions about getting to the next level...

Should I be stropping on a higher grit stone before the leather, and if so what grit? Can I go straight from 1k to this higher grit, or should I stair step?
What "grit" is that green compound anyways?
They mentioned in the book that deburring on edge wood/cardboard/felt tears the burr away and while it does remove the burr, does so violently and is not ideal. Is this the general wisdom, that I should be removing by edge trailing on finer stones? They said to do so at equal angle for high hardness steels, and slightly higher DPS for softer (generalization).
There was a section about how using traditional stones on high-vanadium steels was less effective, because it abrades the steel surrounding the vanadium, and leaves the vanadium proud of the surface - Where it will tear away and leave the edge rougher and weaker - And instead you should use diamond, which can also abrade the vanadium. ZDP-189 seems to have very low vanadium content, but its hard to find a definitive answer - is that accurate? And also, are other carbides also hard to abrade with traditional stones, and is it good practice to upgrade to diamond stones for most high-end steels? My other knives are VG-Max, which does have 3% vanadium, so there's that...

Who knew there was so much nuance to scraping metal off your knives! Thanks in advance!

I'm a bit surprised by the chosen approach. Starting with a relatively fine stone, and wasting time to do on even finer media what hasn't been achieved with the first one. I would start on a SG320 and make sure to have the burr removed as much as possible. I use short edge leading strokes, 1/2", by sections. The idea is to abrade a burr without creating a new one. Only when you can't reduce the burr any further and it only flips you should go to the next stone. About 3/4 of the time is being spent with the first stone. On the next stone a few edge leading or scrubbing motions are all you need to refine the bevels, and loosen the burr, before you start removing it, again with short edge leading strokes.
After the first stone the edge is already very sharp, but cuts of kitchen paper or the finest cigarette paper are a bit ragged. Much less so after the second stone. With the third stone I probably do the same as with the second one. It will take even less time. Cuts have become even smoother. After deburring on the NP3k there's little or no improvement to be expected, except for very finely grained carbon steel, which isn't your case.

 

[Devious Rhesus]

Thanks all! I've been getting much better results by focusing on edge angle by moving slower, and reducing my passes / doing edge leading on the final grit and then fewer passes on the strops to reduce the odds of rounding. The ZDP is arm hair shaving now, and has a lasting edge. I cannot get the VG-Max as sharp, but it's still better than new - So good enough.

As for starting on a 1k, the edges are all in pretty decent shape, so I was able to raise a burr quickly. I am ordering a Shapton 220 though, because I do have a knife that needs some tip work and another that needs extreme thinning to not wedge everything it touches.