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Silly question, how do you "test" if if you're knife is sharp enough...

post #1 of 21
Thread Starter 
Sure, I notice a difference in everyday use, etc. but with the Misono UX-10, I take it to the stones about once a month, how do YOU test to see if it's sharp enough. I usually take some fruit or something laying around and do some before/afters, but only notice subtle differences, unfortunately, I don't have spare meat to test on.

Any good ways for a guy who barely knows how to sharpen his knives?
post #2 of 21
There are different tests for different kinds of sharpness. For the kitchen, one I like is a starchy potato. When cut with a sharp knife, the cut surface is smooth and slick. When cut with a dull knife, it feels pebbly and rough. In many ways, this sort of usage clue and how much effort cuts are taking is your best guide.

But that means you have to actually cut a piece of food you might not plan on cutting. And people just want to know, to verify just how sharp that knife is.

Lots of people, including me actually feel the edge of their blade with their fingers. It's foolish in truth as a well polished sharp edge will eat your fingers to pieces before you know it. But I justify myself knowing that's not the sort of edge I'm putting on my kitchen knives. And most people don't know how to produce that sort of edge.

A lot of people will use a fingernail test. It's useful in some ways though limited. Lightly drag the blade across the face of the thumbnail at right angles You'll notice rough spots that way. Similarly, lightly drag the blade at more and more acute angles to the thumbnail to see how it bites. The lower the angle you can still get bite, the sharper it is.

Lots of people cut paper. A good cut in paper needs a finely polished edge, usually too fine for holding up in kitchen work. Good technique can account for a lot of clean paper cuts that will tear out if someone else were to try it. I tend to use a thin piece of scrap paperboard packaging. It should cut without much pushing effort and the cut should be clean and smooth without significant feathering of the fibers.

If you're experiencing a brief initial supersharpness then quick dulling, that's a sign of a wire edge and you'd benefit from some more practice at sharpening. Stropping can also help clean up a wire edge.
Palace of the Brine -- "I hear the droning in the shrine of the sea monkeys." Saltair
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Palace of the Brine -- "I hear the droning in the shrine of the sea monkeys." Saltair
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post #3 of 21
If it makes you bleed and there is no pain involved/you dont notice the cut than it is sharp enough, otherwise your not quite there yet.....
Taste: The sensation derived from food, as interpreted thru the tongue to brain sensory system.
Flavor: The overall impression combining taste, odor, mouthfeel and trigeminal perception.
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Taste: The sensation derived from food, as interpreted thru the tongue to brain sensory system.
Flavor: The overall impression combining taste, odor, mouthfeel and trigeminal perception.
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post #4 of 21
actually if you ever cut yourself with a razor blade its pretty painful, same with very sharp knife.
here is a link to an extensive guide on knife sharpenig, towars the end there is a list of tests for sharpness:
eG Forums -> Knife Maintenance and Sharpening
post #5 of 21
The two basic types of tests are non-food and food.

Non-food tests have the advantage that you don't waste food or need to use things just because you're sharpening; these include push-cutting paper, hair-shaving, and so on.

Food tests have the advantage that they are a great deal closer to what you actually want the knife to do. There are many of these. The potato slice already mentioned is a good one. I like the overripe tomato and cherry tomato tests.

The overripe tomato test: Get an overripe tomato, place the knife gently near its tip on the skin, blade parallel to the board. Push straight forward. If the knife is very sharp, it will very quickly drop straight through the tomato.

The cherry tomato test (for lunatics only): Set your knife on its spine, edge-up, on a board. Drop a cherry tomato on it from a medium-ish height. Gauge results:

Bounce, no damage: blunt
Bounce, a bit of cutting: medium
Cut and stuck: sharp
Cut cleanly through: frighteningly sharp

The difference between the latter two only works with fairly thin-bladed knives, as a thick-bladed knife has a big disadvantage in cutting straight through.

I'm fond of this test because (a) it's fun, (b) my kids adore cherry tomatoes so I usually have some around, (c) I am always happy to eat another cherry tomato, so there's no waste, and (d) did I mention it's fun?
post #6 of 21
Food tests:

Onion test: Does the knife "fall" through the onion without effort? The fall test will tell you if the knife is sharp or not. Onion tests are great because chopping them is common to so many dishes. Other onion tests which indicate dullness to extreme dullness are crying and color. Does the onion cause crying (sign that the knife is crushing through cell walls, rather than separating them)? Does the onion discolors where the knife touched it? How long did it take to show? Discoloration is caused by the same thing, and indicates a knife which should be sharpened immediately. "Crying" is more sensitive with stainless knives; with carbon they appear at about the same time.

Carrot Test: Similar to the fall through test. Does the knife cut the carrot or split it?

Pepper Test (Completing the Trinity): Will the knife push cut through the skin of a tough pepper effortlessly, or is some "slice" action required

Mushroom Test: Will the knife slice through or chop a mushroom that's been a few days in the refrigerator without any crumbling.

For me and people who cut like me, these test are compromised a bit because our chopping action is a combination of push, shear and slice. I.e., the dreaded "knife skills" way. In fact, part of its raison d'etre is to compensate for a knife which might be a little dull. This means some cutting tests aren't as revealing as they might otherwise be and leads to the tomato tests described by Chris. Also the Mechanical, Finger, and Forum tests.

Mechanical Tests:

Steel Test: After a (correctly done) steeling, was the edge fully restored to "very sharp?"

Steeling or "Touching Up" Just Because Test: Scheduling things before they're needed isn't a test really a test, but it's good practice. I used to steel before I needed it as a prophylactic, but the last year have been steeling only when I feel the need to save the knives some wear. If you choose not to use a steel, you should be "touching" up your UX-10 on your 4K stone something like every couple of hours of knife prep time to freshen the metal at the edge and bevels, and to correct any minor out-of-true issues caused by board impact. Again, a knife that won't steel to better than adequate is a knife that's ready for the stones. Adequate isn't.

Bic Test: This tests polish more than keeness, but it's an excellent test and good for people who like metrics. Slide the knife down the smooth face of a plastic pen as though you were steeling the edge. You'll feel any imperfections in the edge -- whether roll, wave or micro-chip. While you won't feel wear per se, knives never wear evenly and you will feel the unevenness.

Sharpness Tester Test: Just like the Bic Test but with an official, approved piece of equipment that costs money (but not much). You can buy one from Jim Juranitch. He's got an e-tail site which I think is called The Razor Edge or The Razor's Edge or something like that. He wrote (and sells) the best book ever on sharpening for those who use oilstones.

Paper Tests: Hold a piece of paper by the corner out in front of you. Try and slice through the edge with your knife at about a 30* angle of knife to paper's edge. In theory, a sharp knife will cut paper, a dull knife won't. In practice, performance has a lot to do with what kind of paper, how you old it, how you move the knife, and which part of the edge you use (heel's more effective than tip). Once you get the hang of it, you can trust your own testing. But don't read too much into other peoples'.

Touch Tests:

Thumb Drag: Everybody does this one. For some reason, when they get into fancy schmancy knives they stop trusting it. Let your faith be restored. It not only works, it's excellent -- as long as you don't stop with testing one spot. Drag your thumb up and over the edge without too much pressure. Repeat several times along the edge, and from both sides. A barely sharp knife will feel, well, barely sharp knife. A sharp knife will feel scratchy. Sharper feels itchy. Very sharp feels tingly. Super sharp feels "electric," you may not just feel it on your thumb, but possibly on the back of your neck as well. Calibrate your senses for it by (carefully) thumb dragging a fresh razor blade. That's an extremely keen, fresh-metal, polished edge, with a polished bevel. It's what you're going for.

Three Finger Test: This is a Chris Carter test, and is very weird. I don't expressly recommend, but neither do I expressly disapprove. The test is foolish and informative. Obviously you have to be very careful using it. Hold the knife by the handle with your right hand (lefties reverse), so that the blade is more or less parallel to the ground. Place the finger tips of your index, middle and ring finger of your left hand against the knife's edge. Lighten up your grip so the edge rests (or almost rests) on your finger tips. Now ask yourself, does the knife feel so sharp you're afraid to slide your fingers at all? Don't slide them, just ask. If you're scared, the knife is sharp. If not, needs more work. The test doesn't become safer the more you use it. I know because I'm stupid.

Forum (Psychological) Test:

If You Gotta Ask Test: The question, "How do I know my knife is sharp?" as posed in a post is presumptive evidence the knife not only needs sharpening, but is significantly duller than when it came out of the box. (Misono ships the knife sharp, but not as sharp as a UX-10 can get.)

BDL

PS. I alo recommend reading the Chad Ward article on E-Gullet (which I think you've already done; additionally, it's worth reading the Steve Botoroff e-book -- in fact you may get more from Botoroff. That said, both are dated and too brief. There are better sources of information although you have to pay for them. The best is Chad Ward's book, "An Edge in the Kitchen." I've already mentioned Juranitch. Some people like the Lee book (from Lee Valley), but it's more about tools than knives. If all the explanations get tiresome and all you want is "how to," Dave at Japanese Knife Sharpening has an excellent DVD, as do Chris Carter, and (I think) Korin.

Speaking of videos, Curtis aka C-Dawg of Knife Forum and Fred's Cutlery Forum fame has an excellent video on you tube of him sharpening a Mizuno gyuto. It's just hit this forum as a link. Don't try and sharpen like Curtis until you're already a proficient sharpener. His method is method looks extremely good to beginners because it's not all about "feeling for the burr" and "deburring," uses only one kind of stroke, and relies on counting instead of inspection and touch testing. In other words, it seems as though there's so much less to learn. Unfortunately, shortcuts won't get you where you want to go until you've walked the whole path a few times. I won't post the link, but did describe the "Three Finger Method," read into that what you will.
post #7 of 21
My first thought was to say start chopping at a block of wood and if it cuts it through it's sharp or maybe hit your co worked in the arm....if the arm comes off then it's sharp. REALLY JUST KIDDING HERE!!!!!!!! Seriously though, I scrape my thumb over the business end to see how it feels. :look:
post #8 of 21

Testing Sharpness

TESTING SHARPENESS
To be sure you are improving your sharpening; you need an objective way to test the results. Tests evaluating sharpness range from cutting silk to chopping trees. What you need is a test method that are useful in your workshop as you are sharpening.A major knife maker tests sharpness on nylon paint brushes.

Most people test an edge by rubbing their thumb lightly across the edge and feeling how the edge grabs as it tries to cut into the thumb pad. To keep your thumb calibrated, test a known sharp edge like a new razor blade periodically.



[LEFT][LEFT]Shaving hair on your hand or arm is another common sharpness test. Shaving sharpness can be achieved even on heavy hunting knives or an axe. I own a hunting knife that will shave even though the edge angle is a rather blunt 30 degrees. I use the term shaving sharp to describe this degree of sharpness and razor sharp to describe even greater sharpness. Razor sharpness is comparable to a razor blade and will literally pop the hairs off your hand or arm. Razor sharpness is only possible with both a polished edge and a small edge angle.



[/FONT]
[LEFT]
Testing by shaving can be misleading if the blade has a burr or wire edge. Steel naturally forms a burr - a thin bendable projection on the edge - during the sharpening process. A blade with a burr will shave but will not stand up to hard use. To test for a burr, slide your fingertips lightly from the side of the blade over the edge. You will feel the burr drag against your fingers. Test from both sides, because burrs are usually bent over one way or the other. As your sharpening improves you will be looking for smaller and smaller burrs.





The glint along this edge means a dull blade.[/FONT][/COLOR][/CENTER]
[/CENTER]
Many good sharpeners, including my grandfather, have learned to see a dull edge. Hold the blade in front of you with the edge in line with a bright light. Move the blade around a bit. A dull edge will reflect a glint. Nicks and burrs will also cause glints. When the blade is sharp these glints will be gone.
Another test for sharpness is to press the edge lightly on your thumbnail at about a 30-degree angle. If it cuts into your nail it is sharp. If it slips it is dull. The sharper the blade, the smaller you can make the angle before it slips. Try this with a new razor blade to see how a really sharp blade feels. The down side of thumbnail testing is that the little cuts in your nail get dirty and look bad until the nail grows out. For this reason some people do this test using a plastic pen or pencil.
post #9 of 21
Sorry to resurrect an old thread, especially since it's just to bust on you!;):D I think you mean "Murray Carter"- Chris Carter is either 1) on of the best wide-outs to every play in the the NFL or 2) the guy who made the X-Files.:D
"Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit." - Aristotle
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"Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit." - Aristotle
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post #10 of 21
Actually, I'm glad you did, this is a pet peeve of mine.

I believe clients and chefs don't have to check their edges--that's because I do.

Here's an example. Let's suppose that you are a noted chef for a multi-star restaurant. A diner visits your establishment, and orders your signature dish. For the sake of this debate, you watch as the diner looks at your superior presentation, wafts the unique blend of spices you've developed, and with anticipation, you hope to catch the look on his face for that first taste and his Epicurean delight.

Instead, the diner jams a piece of litmus paper into your sauce.

Shocked, you immediately question the diner, and his response is simply, "I was checking for putrified water..."

I polish, you slice.

First off, the "three finger method" does nothing but check the sensitivity of your fingers, not the quality of my edge. A calloused old farmer would feel nothing. This is an old technique called "tickling the dragon" in some Asian polishing circles, and it's usually for bragging rights.

If you cannot slice your required ingredients, return the knife to your sharpener, or find a new one. New super and uber steels require study, special stones, heightened procedures and years of practice. A harsh hand and a hot grinding wheel can delaminate folded or clad kitchen knives.

Since I open numerous UPS boxes for my business, I always carry a folding knife for chores. I have long since quit lending it out, or even showing it to the people I meet.

They all did the same thing--rub my edge with their thumb. I don't know what they're trying to ascertain, but I got tired of polishing out thumb prints and wiping off a stranger's DNA.
post #11 of 21
How do you test an edge is sharp enough? If I had my knives sharpened by someone else (I don't; I don't have anything fancy; I can do a fine job myself, in less time than it would take to take them somewhere (which would likely have to be a post office...)) I'm willing to believe they'd come back sharp. But what do you do to make sure they're sharp before returning them?
post #12 of 21
How do you even resurrect a thread like this?! Were you just browsing threads many pages back?! And you reply to the most random thing! Haha, crazy ... :beer:
post #13 of 21
Drop test with celery with the fiber side down. If it bounces off dull (my sisters knives!), cuts and sticks semi sharp, cuts completely in half with no tearing of the fibers sharp.
post #14 of 21
The "feel" of the edge on polishing glass, and intense light under high magnification.
post #15 of 21
Hi all,

I got my new stones today for my EdgePro and thought I would check through a few of these threads just to see...(use big ominous voice with slight echo) HOW SHARP CAN YOUR KNIFE GET!

I've got the full complement of EdgePro stones, although no polishing tapes. In addition I have the Shapton 320, I had the Chosera 600, Shapton 2000, Chosera 5,000, Shapton 15,000.

I'll buy a Shapton 1,000 when they get one in...but for now these are the stones that I have to work with. I must say...so far I'm really liking the feel of the Shapton pro stones. I can't wait to get more time with the new stones...But I feel I have to limit myself :rolleyes: I don't want to grind my knife down to toothpick :lol:

As I improve my skills...how sharp can my Masamoto HC get? I'll pick up some cherry tomatoes and over ripe tomatoes...but I hate to buy grocery store tomatoes in winter, yuk! I'll try the celery test for sure.

Using the paper test I could hold the paper in one hand with the knife starting away from the edge of the paper. Then strike the knife down to and through the paper in one downward stroke. The cut is clean, can be thin and through the paper. I can also cut a small circle in the paper with clean cuts as well.

Do these tests mean anything? I don't know??? I do know I'll be paying more attention on how long this edge will last being super sharp. I'm currently sharpening a single bevel @ 13*.

I have no doubt that there are many that can freehand with better results. I'm just starting off and still have much to learn. But I'm so glad I decided to get the EdgPro Apex. I just don't think I'd be anywhere near the results that I'm getting without it.

Does anyone have any other good tests?

Stay sharp my friends,

dan
post #16 of 21
They're in stock now, but be warned; you-snooze-you-lose. They won't last long. But Ken's got a new saw on the way, so hopefully production should be back to normal.

I got a package of stones in the mail yesterday. All EP versions of the Naniwa Choceras in 1k & 5k. Tomorrow another shipment should be here, a backup 400 Chosera and a couple OEM EP stones. Altogether I have Choseras in 400, 800, 1k, 2k, 5k & 10k- plus Shaptons in 320, 1k, 2k, 5k, 8k & 15k, plus a synthetic Aoto. I haven't had a chance to compare them all yet but if we get the storm we're supposed to I'll have the whole weekend to play with them.:lol:
"Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit." - Aristotle
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"Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit." - Aristotle
Reply
post #17 of 21
I'd love to read your thought comparing the Shaptons up to 15k and the Chosera with the 5k, 10k finish. I won't be changing from my 15k Shapton anyway, the Chosera 10k is just too much money right now. But I would like to hear any differences.

I may see if the 1k is still in stock. I still can't believe how sharp this knife gets when stepping to the Chosera 5k, Shapton 15k finish stones. So much different than OOTB :thumb: (and it wasn't too bad out of the box!)

Now I just have to keep from sharpening this thing too much :)


dan
post #18 of 21
It doesn't apply at all to using it an EP, but a lot of freehanders found the Shapton Pro 15K (the same stone in Japan is listed as 12K, FYI and FWIW) to be hard, slow and practically unusable. Dave Martell (or JKS) did a very interesting comparo with it and a few other finishing stones either in his blog or in the KF. I haven't had much actual experience with the 15K, and the little I had is a datapoint falling between "it's a pig" and "difficult but useful" on the ol' bell curve. Maybe more time to fool around would have revealed the magic techniques.

In any case there are better, faster finishing stones for freehanding; among them Chosera 10K; Kitayama; all three Naniwa SS 8K and above; "Naniwa ebi 'Pure White' polishing stone" (incredibly good 8K); the often overlooked Ice Bear 10K; and probably a few other synthetics I can't think of off the top of my head.

But early reports from EP adopters call the cream-colored Shapton a wonderful stone. Great news! We need more of them -- or at least you EP guys do.

The Chosera 10K is definitely a great bench stone. It's biggest (freehand) virtue is speed; otherwise there are other stones just as good and better -- and significantly less expensive. Even a Pure White/ Kitayama combination -- pretty close to ultimate -- is less.

Though not an EP guy, I look forward to hearing more from Phaedrus. It's a good thing he's got the time and the money. Dave and Barry, the wood-working friends who were compulsive stone buyers and my "lend me your stone" sources, seem to have settled in with their current kits. Darn it. During the last five years, my last water stone kit but one was stolen (the four Nortons of the Apocalypse), and the last one (three Shapton Pros and a Kitayama) went with my son -- along with four Hiromoto knives.

Since buying my current set, with so many stones bought over such a short time, it seems, by necessity, I've settled in too. That is, unless KC starts coming through.

Consequently Phaedrus ol' top, let it not be just the fine grits. Write about the others too -- especially the Shapton Pro 5K. It's another stone many freehanders love to hate. Max (my son) won't use it. I thought it was weird but wonderful -- a palpable hit.

BDL

Current kits -- Oilstone: Norton Coarse India; Norton Fine India; Hall's Soft Arkansas; and Hall's Surgical Black Arkansas. Water stone kit: Beston 500; Bester 1200; Chosera 3K; and Naniwa SS 8K. Rod hones: 12" HandAmerican borosilicate; (worn-down) 12" Henckels "fine."
post #19 of 21
Stones are a different animal in the EP than used freehand. I honestly don't think many people have the skill and phsyiological capability to to wring the performance out of a hard, "unforgiving" stone like the Shap Pro 15k when used freehand. A stone that fine cuts slowly, and errors multiply. By the time you've abraded enough metal you've rounded everything off...and then you blame the stone. The EP gives you the control over angles that lets you unlock that stone.

So far I've only done 1 knife with the all-Chocera lineup. Obviously I can't make any sweeping statements from a single use but my initial impression isn't so much that the 10k Naniwa so much gets it sharper, it just takes less time and effort to get that edge. They both get you to the same place, but the Shaptons get you there in a Toyota Camry and the Chocera delivers you in a Bentley.
"Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit." - Aristotle
Reply
"Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit." - Aristotle
Reply
post #20 of 21
I'm sanguine my complaints about sharpening on a Shapton Pro 15K don't stem from bad technique. Other freehanders, possessors of madder skilz than mine, feel the same.

A preferable hypothesis than "BDL can't sharpen" might be: The SP 15K works better "sectioning" than with full strokes. In other words, it functions better as a large "finger stone" than as an ordinary bench stone. To avoid creating a burr, most good, freehand, kitchen knife sharpeners don't section while polishing. Thus that particular idiosyncracy might have been overlooked. The thought also goes some way to explain why people who sharpen reed knives, razors, chisels, planes, and other relatively short blades seemed happier with the stone.

Hypotheses aside, I very much want to hear what Phaedrus has to say about how it works on various knives in the EP.

BDL
post #21 of 21
Let me clarify- I shouldn't have said "skill." It has more to with the limits of the ability of the human hand to maintain an angle. Some stones are "softer" or more forgiving, but the SP 15k is not. If you wobble at all or make a minor mistake it really seems to take the zing off your edge. Anyway it's just a theory. No one seems to like that stone freehand but everyone I know who uses it in the EP or Gizmo is impressed by the stone.
"Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit." - Aristotle
Reply
"Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit." - Aristotle
Reply
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