General Q's about sharpening

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jferreir

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Excuse the silly questions, but I don't know where else to turn...

I have a Naniwa SuperStone 1k/5k combo, but the 5k leaves absolutely no bite. It will literally squish a tomato before it can break the skin; even splitting an onion is difficult. Oddly, if I use a different but comparably high grit stone (4k or 6k), I don't have this same issue. Why? Is it the steel? The abrasive? The grit size? FWIW, I tried this on a few knives, and the results were consistent (AS and W#2, iirc).

Separately, I own a single natural stone: a small Koppa (~$60). I understand this is a "finishing stone", but I find it has a great amount of bite -- similar to a 1k stone, but the edge lasts much longer. I typically use this stone to finish my carbon knives; it works particularly well on my Takeda. The Koppa is beginning to dish ever so slightly -- can I safely flatten this little guy with an Atom 140? I just picked one up and it cuts super fast, so I'm a bit hesitant to give it a whirl. I do have a nagura that I can follow up with, however.

More generally, how do you select which stone for which knife? How should I use the Koppa? Only after a synthetic stone progression, or for moderate touch-ups?

Lastly, I purchased a strop for maintenance (one that lies flat like a stone), but I only dull my edge whenever I use it. I've tried adjusting my technique a bunch of different ways, but no matter what I do, I always ruin/dull my edge with it. I don't even know what I'm doing wrong... help?

Thanks, and sorry for the book!
 
The 5k stone, has it been heavily used? Is it filled with swarf? Has it ever been lapped? Regarding the strop, it sounds like you're using to high of angle and rounding or dulling the edge.
 
Is your strop loaded? you may try to use denim (unloaded) to strop. I find that it leaves slightly more bite than using a loaded/or unloaded leather strop. Also, for good slicers (for tomatoes, protein, etc) i've personally found stropping on unloaded denim after coming off a lower grit stone to be helpful (1k-3k)
 
M1k3 said:
The 5k stone, has it been heavily used? Is it filled with swarf? Has it ever been lapped? Regarding the strop, it sounds like you're using to high of angle and rounding or dulling the edge.
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It's been used about a dozen times, flattened, and the swarf cleaned with a synthetic nagura. I just don't understand it... 3 passes on my 3k brings it right back to razor sharp (by amateur standards, anyway).

I don't doubt that I'm rounding the edge on the strop, I just have no idea how to improve my technique. I've tried shallower angles, less pressure, etc. -- I think the problem is just piss-poor angle consistency. I stopped stropping altogether because it does more harm than good.

jaeysehn said:
Is your strop loaded? you may try to use denim (unloaded) to strop. I find that it leaves slightly more bite than using a loaded/or unloaded leather strop. Also, for good slicers (for tomatoes, protein, etc) i've personally found stropping on unloaded denim after coming off a lower grit stone to be helpful (1k-3k)
Click to expand...

Unloaded leather strop, but I do have a small spray bottle of 0.5 micron diamond spray. Bought it as a last-ditch effort, but haven't had a chance to give it a whirl. I wanted to improve my technique before trying the diamond spray, but I feel like I'm regressing...

And sorry for the late reply!
 
To me it sounds like u use too much pressure, and don’t have a consistent angle when u sharpen.
The finish stone can be harder than ur mid gritt and therefore more unforgiving with pressure.
Can u explain in short how u sharpen etc ?
 
Thorndahl88 said:
To me it sounds like u use too much pressure, and don’t have a consistent angle when u sharpen.
The finish stone can be harder than ur mid gritt and therefore more unforgiving with pressure.
Can u explain in short how u sharpen etc ?
Click to expand...

I think I have decent consistency sharpening the right side of the blade (I'm right-handed), but I have difficulty maintaining a consistent angle on the left side. I typically switch hands to maintain the largest amount of surface area between the edge/stone to minimize wobble and inconsistency. In generally, I can get my knives shaving sharp -- consistent polish along the edge.

No issues with 1k, 3k, 4k or Koppa... just the 5k gives me issues. It's difficult to describe, but after finishing on the 5k, the edge has difficulty breaking vegetable skin, and the knife won't glide through product -- as if the product gets stuck to the side of the knife. A few passes on literally any other stone resolves this.
 
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I reiterate the question. Does 5k feel softer to you compared to the others?
If so, maybe you just haven't got enough practice with softer stones and can't adjust accordingly. When you will be able to do this, you will discover that even the stones you knew are starting to give much better results. Pressure control and consistency.

Naniwa SS 5k is a softer polishing stone.
 
My thoughts..
.main point: do you manage to rise a burr with the 5k?
.if you cut food only, 5k is too fine for many tasks.
.If your strop dulls the knife then there may be an issue with the consistency of your angle. Generally, light pressure gives a worse consistency or more difficult to achieve.
 
Since you tried different stropping techniques, I could see one possibility with having some kind of a false edge from one stone and the strop just to remove it. Seems very strange to lose sharpness trying everything. Now I wonder if the 5k doesn't do the same and not being able to make a new one fast enough so the knife feels dull. And I wonder how hard or fast are the other stones. Since even something like Norton 4k can be plenty fast with a few passes on most alloys.

For us, this is a pure guessing game. I've seen many things.
 
kayman67 said:
I reiterate the question. Does 5k feel softer to you compared to the others?
Click to expand...

No it doesn't, but what the hell do I know -- I'm an amateur at best.

I have the Naniwa SS combo stone, and then a few Morihei. The Morihei feel softer, but work faster. No issues with any stone except the Naniwa SS 5k. I have zero confidence in my ability to detect a burr above 1k, for the other guy who was asking. I usually just sharpen until the edge is polished and it cuts well.

Literally 3 passes on this stone is enough to dull the edge. 3 passes on any other -- including the presumably harder Koppa -- puts things back to normal.
 
jferreir said:
I have a Naniwa SuperStone 1k/5k combo, but the 5k leaves absolutely no bite. It will literally squish a tomato before it can break the skin; even splitting an onion is difficult.
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I know this stone and I know your problem. It is is simple, the Superstone 5000 leaves a higher polish than a average 5000 and no bite. Good for pushcutting, bad for slicing/ripping tomatoes.

You need a very good technique to geht your wanted results with this stone. But, it is possible. Keep in mind that a razorsharp edge without bite is not the best choice for all kitchen tasks.
 
KingShapton said:
I know this stone and I know your problem. It is is simple, the Superstone 5000 leaves a higher polish than a average 5000 and no bite. Good for pushcutting, bad for slicing/ripping tomatoes.

You need a very good technique to geht your wanted results with this stone. But, it is possible. Keep in mind that a razorsharp edge without bite is not the best choice for all kitchen tasks.
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Ah, this make sense! Makes me wonder though, why would someone choose this stone/level of polish? When does someone NOT want any bite? FWIW, I almost never use this stone for the reasons just discussed.

As for the strop, I suppose it's less forgiving of poor technique. I've definitely seen improvement in my sharpening over the past few months; stropping, not so much.
 
I bought the stone out of curiosity. Reasonably priced, but as good as new.

Although I have learned to deal with him and achieve good results, even for the kitchen, I would definitely not buy it again.

On the other hand, the razor guys seem to love the superstones, but they have other requirements as well.
 
A good use for the stone is polishing the secondary edge after thinning, before sharpening the primary edge. The results are really good, mostly I use the stone like that. Mostly for stainless steel.
 
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I agree with @M1k3 and @Thorndahl88 --and my thinking is to combine their advice. Try going much lighter on the 5000, and definitely put a focus on not wobbling.

If the 3000 brings the edge back and the 5000 loses it, my thinking would be that this points too too much pressure. Where instead of refining/polishing the edge already on there, the 5000 is slightly re-setting the edge in places.

Plus, it's possible the left hand wobbling's doing it. 3000 cuts well enough because it's coarse enough to hide some flaws. Spine too high rounds the edge and spine too low doesn't reach the edge. Combine these two, and that's an inconsistent edge. Then strop that, and it's potentially an inconsistent edge that's shinier.

Which brings us to the strop. Forget it. The results aren't good probably because it is too soft. Opinions differ about whether soft of hard strops work best. Soft strops have more potential to round the edge though. If the strop is making things worse not better, take a break from using it. Or try newspaper instead.
For that matter, maybe take a break from using the 5000 too. Plenty of people on here enjoy a 3000 grit edge. A very toothy edge might be just your preference?

As to the Koppa--sure flatten it with the atoma and nagura. There's a rule of thumb about the benefits of 140 vs 400 Atomas for j-nats. I forget what it is, though :)
 
Even a softer strop with no compound should not kill the edge with every single technique, unless a lot of pressure is used all the time (really pushing and that's not actually changing the technique) or there's something with the edge itself. I strop sometimes on my shirt (even my razor after a quick touch up). Never got a dull or damaged edge from it.

I've seen people struggle with SS 5k until they got the hang of it. It is a softer polishing stone, with a learning curve conditioned by these elements. This part is usually the starting awareness point. That's what I wanted to know.
It's a difficult guessing game since here could be a series of factors working together, not just one. For me a polished edge should still be able to cut any tomato skin just fine.
 
Strop really lightly. You just want to"clean" the blade.

Also, do you clean the blade after sharpening and before testing it?
 
Eh, re strops, most people seem to use leather glued to wood. Does balsa work as well? I was thinking of using a 40*10cm bit with some diamond paste.
 
Balsa with diamond paste works for razor guys, should work also for knives.
 
I have tried lots of different strop materials. I would say leave the leather to the razor guys unless you have a very hard fine strop. And then it's still not the best.

My favorites for knives are denim stretched tight over a wood block loaded with CrOx or a 1/2" felt block loaded with CBN.
 
I use 2 different balsa strops. A 1 and 3 micron diamond paste. I use the 1 micron after sharpening. 3 micron stays in my bag for touchups at work. I like the stiffness. If I dull the edge, I know my angle is bad. If nothing happens, my angle is bad. If I hit the target, I get sharpness improvement.
 
stringer said:
I have tried lots of different strop materials. I would say leave the leather to the razor guys unless you have a very hard fine strop. And then it's still not the best.

My favorites for knives are denim stretched tight over a wood block loaded with CrOx or a 1/2" felt block loaded with CBN.
Click to expand...
That’s jolly. It’s always much nicer when you can repurpose scrap (old jeans and cupboard off cuts) than purpose buying things.
 
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