Stropping, Steeling, Sharpening

Citori

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Sep 28, 2002
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I've read a few sharpening FAQs, including the one here, but I still have some questions about the differences between the various methods of getting an edge on a knife.

My questions run along the lines of what is actually, physically, happening to the knife. I gather that idea behind sharpening with a stone is to remove metal from either side of a blunt edge until the two meet. Frequently I read people referring to using a steel to 'realign the edge'. Does this differ from sharpening? If so, how? Does stropping accomplish the same thing as steeling? How would you know when to use each technique?

Probably the difference is in the amount of metal removed, or in the quantity removed with each pass, but I wanted to be sure. I have a Henckels kitchen knife that I use every day that has only been steeled. It seems to stay quite sharp, so I'm thinking maybe I sharpen my other knives too much and should just be steeling them.
 
Citori :

[steeling]

Does this differ from sharpening? If so, how?

Steeling with a smooth steel, takes an edge that is bent and dented and restores it to a crisp and straight line. You can readily see the difference by using a cheap magnifier and looking down into the edge before and after steeling. It is best done with the edge illuminated.

Does stropping accomplish the same thing as steeling?

It can, if you use the strop bare and it is a much slighter action then than a smooth steel. But usually a polishing compoung is used on the strop which will remove metal like a hone, but much slower.

How would you know when to use each technique?

They are usually for two different grinds. Convex edges tend to get stropped and v-ground edges tended to get steeled. But you can swap them around.

I have a Henckels kitchen knife that I use every day that has only been steeled.

Many common kitchen steels are not smooth but are grooved, these can act as fine files, and thus remove metal like a hone. However if you go very light you can focus on aligning the edge with them as well. The edge they produce tends to be more ragged than with a smooth steel, which gives in general better slicing performance.

-Cliff
 
I would say the majority of the people here sharpen their knives way too much, at least that is what I gather from hearing them talk. The difference with the methods is, the sharpening removes the most metal. It is for repairing a really dull knife, or for grinding chips out of the edge. Usually, once the knife is sharpened, you finish the edge on a leather strop charged with some CRO2 or other polishing compound. This removes much less metal than actual sharpening. It is really used to remove the wire edge, or the very fine, unusable edge that is formed from sharpening. If the wire edge is left on, and it is straight, the knife will seem super sharp until you use it once, and the edge rolls over making the knife seem dull. Once you have removed the wire edge or polished the edge to your liking, then you really only need to maintain your edge with the strop and steel. A sharp knife's edge is so thin that it will tend to deform and roll with use. This makes the knife seem kind of dull, and this is where most people sharpen their knife. Knife manufacturers would love you to take this method, because it means you will grind your knife to an unusable state much faster, and thus buy more knives. Others who know the value of the strop and steel will just lightly stroke one or the other to realign the edge, or draw it back straight. Personally, I will run my knife along a tanned, uncharged, leather hone, and then check for sharpness or if the rolled edge is still there. If it is, then I will lightly stroke my smoothe steel a few times and again check the edge. If it still isn't satisfactory, then I will use the very finely grooved side of my steel. If for some reason, I have let my knife get really dull, or just used it really hard, these things won't work completely. Then I will lightly stroke the fine stones on my Sharpmaker 204, going backwards from the order you are supposed to do. I will start on the white flats, and if that doesn't do it, then I will go to the white corners, and so on. This way, I'm removing only as much steel as needed to get my edge back to scary sharp. If you do these things, your knives will last much longer.

Mike
 
uhm
i dunno about steels and strops, haven't had a chance to use them
but i find that for most touchups, all i need is a triangular ceramic hone
for removing chips, i use a DMT diamond diafold
keep in mind i only have blades with flat grinds and reprofiled round edges (now flat) tho
 
Steeling and nonabrasive stropping do not yield as stable an edge as honing. When you bend the misaligned portions of the edge back to center they tend to creep back out of alignment. This effect takes hours and is partial. If you are a barber you strop before you use your razor. If you are a meat processor you steel before you cut.

Steeling can also overstress your edge and cause metal fatigue. This can cause the edge to be less durable than a properly honed edge. Stropping can give you an edge that is overly smooth and that slices less aggresively than a steeled or honed edge.

If you have enough knives overhoning is not much of a problem. I may wear out an SAK in 5 years using a diamond hone and a Sharpmaker, but I'm not going to worry about it. I typically sharpen one of my kitchen knives a day. I really can't see significant wear. Of course I've got about 20 kitchen knives in my primary rotation.
 
For some of us, anything that will give us a good excuse to buy a new knife is a good thing to do.
 
Cliff and Mike pretty much summed it up, imho.
I will add only the following. I have a very smooth, high polished steel that I use when a customer brings in knive that has a small dent in the edge, where the steel is still there, just moved to one side or the other. I actually use this steel to work the steel that has been folded over back toward the edge and smooth it out. Then when I sharpen the knife, I don't have to take as much off, and the knife lasts longer. I also use this steel in the way that Mike mentions, to bring a rolled edge back up.

For the most part, I don't recommend that my customers use a steel on their knives, unless they know what they are doing, and strongly suggest they keep any knife I sharpen away from a serrated steel. This is mainly because steeling a sharp knife can actually dull a knife by ripping the fine edge off (mainly talking about fine kitchen cutlery). I have had some customers take a knife I just sharpened and put it too the steel, out of habit, pretty much ruining the work I just did. I shouldn't tell them, as it means they will need the knife sharpened sooner, but I just feel for the blade, I guess.
Now if the edge is already dull, steeling can make it somewhat "sharper". But I feel, if it is dull, it should be correctly sharpened. Although, that is not always possible due to time or the situation.
Just some thoughts, correct me if you think differently.
Brome
 
The steel I use is highly polished, glass smoothe on one side (actually almost 3/4 around), and very finely grooved on the other side. These grooves are so small, I almost thought they sent me a full smoothe steel. They actually put a notch on the tip of the steel to give an indicator of where the grooves are. The only thing really visible is the steel goes from highly polished, to a slightly duller appearance. These grooves are not aggressive enough to remove metal like the cheap grooved steels that usually come with boxed kitchen cutlery, but are just aggressive enough to work on an edge that doesn't respond to the highly polished side. I highly recommend this steel to anyone. Here is where I got mine. While you are there, check out their high quality Pro Combo Leather Hones. Very high quality product, and very good customer service. When I ordered mine, it was during the new year holiday, and took them a little longer than normal to get my order out. Since they hated taking a couple days extra, they threw a high quality ceramic steel in for free! This can be used to sharpen, or when the true steel doesn't work well. Personally I like the Sharpmaker white stones for this instead because the ceramic steel seems coarse to me, but it was still very nice of them to throw it in for free.

Mike
 
Will a perfectly sharp edge, in other words, one that comes to an infintely fine point, cut through any material with zero resistance?

Perhaps this is answered by "only if the angle of the bevel is infintely small, in other words, non- existant"
Thus, the perfect knife has a non-existant blade.
I am going to go out and by some nice stag antler material for a perfect full tang knife with no blade...
 
Thanks for the great source, Mike. Those are some nice steels.

I actually made my smooth steel by sanding and polishing an old Henckles butcher steel.
Brome
 
Originally posted by Garretts
Will a perfectly sharp edge, in other words, one that comes to an infintely fine point, cut through any material with zero resistance?

I sense the exageration, but obviously you will always have some resistance, no matter how sharp your knife is. You just might not really perceive it with your hand though. And obviously, some material is hard enough to cut, that no matter how sharp your knife it, it will still require considerable effort, but not as much as with a dull knife. I have gotten to where I can look at my edge and tell that it is sharp. I saw a tip on here about using a photon light (or something with a small bright source) to look for a wire edge. I can use my Photon light to see if any wire edge or burr is still on my knife, and if so, I hit the strop some more. I can also use the light to see if the bevels don't really meet by reflecting light off the edge looking down on it. A truly sharp edge will not reflect any light at all. If your edge is rolled, it will be visible with the light reflected from the side. This has allowed me to truly know if my wire edge is gone, or just straight (I don't want it straight, I want it gone). I can now see a wire edge that is so small I can't feel it with my fingers like I used to do. BTW, if you do use your finger or thumb to check for a burr (which is still effective), I suggest you try a method I found to be better for me. I used to use the center of the pad on my thumb or finger, but realized that the skin is thicker, and thus not as sensitive to very small objects like a very fine burr. I found that if I use the very soft skin along the side of my finger (right beside the nail area) I can feel a burr that is too small to feel with the pad on my thumb. YMMV, but this is how I know if my knives are truly sharp. Of course, there's nothing like seeing the hair on my arm fly with no effort;). Also, you can tell if your edge has good bite by touching it to your hair on your head very lightly. Kind of like testing on your fingernail, but since repeated tests on your nails causes grooves that will hold even a duller edge, I find the hair to be more reliable. If the edge bites and holds from sliding down your hair, then it is sharp.

Mike
 
If you are checking for sharpness, where do you hold the light, on the side, or above the edge? Thanks.
 
I am still stuck on "how sharp?"
One of my favorite stories is that someone tested one of the superior swords of the time against a murasama sword. This was done by placing the sword in flowing creek with leaves on the surface. The superior sword cut the leaves as they flowed into it. But the leaves flowed around the murasama blade, avoiding it.
somehow, I don't think this edge was produced by a kitchen steel.
 
To see if the edge bevels meet properly, then the light should shine from overhead. A bright room light will work. Just hold the knife with the edge facing up, looking down on the edge. You are looking for any reflection. Move the knife a little in all directions to make sure the light reflects toward your eye. With practice it becomes very easy to see.

To check for a rolled edge or wire edge, hold the knife with the edge facing up with the knife sideways so you are looking at the profile of the knife. You want the edge somewhat facing away from your eyes. Take your bright light and hold it near your eyes, shining directly on the edge. You want to hold the light in a way that the body of the light blocks the actual bulb or direct light from being in your vision. The light will be shining in the direction that you look, and the light will reflect off of the wire edge only. It will look like a very fine line of light that may or may not go the entire length. I usually hold the knife close to my face, and start toward the handle, and move the knife to shine along the entire blade. It is hard to describe with words, but I hope you get the picture. If you give it a try, you'll find what works. Once you see what I mean, you will find yourself checking routinely for rolled sections.

HTH,

Mike
 
Garretts :

Will a perfectly sharp edge, in other words, one that comes to an infintely fine point, cut through any material with zero resistance?

Yes.

Perhaps this is answered by "only if the angle of the bevel is infintely small, in other words, non- existant"

The critical point is "through". When you are cutting, part of the force goes to actually making the cut [sharpness], and another part of the force comes from having to push the already cut material out of the way [blade profile]. Thus an perfectly sharp knife will start a cut with no force, but it will require force to continue the cut.

In reality you can't get a "perfect" edge beause the edge thickness has a lower limit. Steel is made up out of finite elements and these determine the size of the edge. The grain size of a steel, at its finest is about 0.1 to 1 micron. This then would be the limit of the sharpest edges.


-Cliff
 
Cliff writes:
"The grain size of a steel, at its finest is about 0.1 to 1 micron. This then would be the limit of the sharpest edges".

Awesome reply Cliff. Thanks. What is the best way to measure this? Also, does sharpness really equal cutting ability, or does that vary by material? In other words, does the rough surface of an edge actually serve to "saw" some materials? Does this explain the drawing characteristics of even the best edges? That resting with their own weight on a material, they do not cut until drawn across the surface?
Has anyone written anything good on this topic?
Also, does this mean steels with a finer grain size like cpm 440v or cpm 10v have a greater potential for sharpness?
Also... well maybe that's enough for now, you can see I have a lot of questions on this topic.
 
I do not mean to be defeatist but I cannot get as good an edge as the factory. I just got 3 knives back from Spyderco to have the points reground. Of course they sharpened the entire blade as well. They probably use a belt sander of some sort and a jig to hold the angle consistant and the blades all came out very sharp.

I have used good stones and presently the Sharpmaker but I cannot even duplicate the factory edge! I am thinking about getting the diamond triangles but maybe I should buy a small benchtop vertical belt sander. What do you think?
 
Thanks very much for all of the replies. This motivated me to take a look at my workhorse kitchen knife and my EDC Delica under a magnifying glass, interesting stuff.

There are actually quite a few small chips (a couple of large ones on the Delica) on what looks to the naked eye to be a smooth edge. Gotta learn how to do all of this sharpening, steeling, and stropping properly I think.
 
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