Knife Steeling And Stropping What They Really Do

By: nonstickron

Apr 11 2012

Category: Uncategorized

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Steeling, and stropping for that matter, are very simplistic procedures, very useful and helpful, but very misunderstood and when performed incorrectly become very destructive for the edge. Steeling being the more misunderstood and abused of those two. Although, those two processes do serve the same purpose, both very often are mistaken for sharpening, which is a completely different process. What’s strange and bad, you see a lot of wanna be experts, seasoned cooks, including celebrity chefs, and I don’t know who else, rubbing their knives vigorously against the grooved butcher’s steel telling you how this sharpens a knife. That is plain wrong and grooved steel is a crime against the edge anyway 🙂

What Steeling Is Not

– It definitely is not sharpening. Sharpening, by definition is the process of removal of the metal from the knife edge to make it thinner, i.e. sharper. However, this is not the only way to make the edge feel sharper. That’s when steeling is done correctly. What’s real bad when you see some dude rubbing his butchers steel against the edge real fast and without looking at it, telling you or in the camera how this is the way to sharpen the knife. For one, unless the angle of the knife matches the edge there’s only two possibilities, a) knife is held at a higher angle compared to edge angle, then you simply dull the knife, nothing else, well if the guy used a grooved steel, he’d rip chunks of the edge out; b) knife is held at a lower angle than the edge. Then the result is exactly zero, the steel goes against the edge shoulder and does nothing to the edge, simply because it never touches it. At best, that person is scratching up the knife somewhere in lower 1/3 or even midsection… Sad part is that novices look at this “expert” and being impressed by his fast and vigorous motions, mistaking those for the real skills, try to do the same, and more often that not, destroy the edge. And it doesn’t matter who does that, your local butcher, celebrity chef or just another fellow claiming to be the sharpening guru, it’s still wrong.

Folded edge of the Henckel Chef's Knife'

Why the edges dull

– Contrary to the popular belief, knife edge doesn’t get dull because it looses the metal due to the wear, i.e. because rubbing it against the cutting medium and loosing atoms to that. Well, that wear happens too, but to a very little effect. The edge, at least a sharp edge of the blade is very thin piece of metal. The thinner the edge, the sharper the knife. To make a cut, the operator presses the edge against the medium, pushes or pulls, or both and the medium is cut. Anyway, simply put, the edge is a thin strip of metal that is subjected to significant amounts of pressure, hundreds or even thousands of pounds, and unfortunately, thanks to the human nature significant lateral loads too. It’s very hard to keep perfectly straight angle during the cut, the knife wobbles a bit, thus those lateral loads. Vertical pressure is tolerated well, but lateral (i.e. side to side) pressure or loads deform or even break the metal a lot easier. On the two photos attached to this paragraph you can observe deformations suffered by Global G-61 Chefs knife and Henckel Chef’s knife. Both knives are relatively soft steel, not higher than 58HRC. Still, you can see large section of missing metal on G-61. Most likely metal fatigue, we’ll talk about that a little below.

What exactly happens, i.e. whether the part of the edge will break or fold to the side depends on the steel properties and Rockwell hardness. Harder the steel, higher the chance of chipping. Obviously it also depends on the force applied. For example, this photo of the edge on the 270mm Aritsugu A-Type Gyuto clearly shows the type of edge wear and dulling harder steel knives are prone to, it looks more like a micro saw under the microscope. Even if the steel isn’t all that hard, 60-61HRC, still it fractures on microscopic level, and doesn’t bend that much. Although, I don’t want to give you an impression that all hard knives always chip. Not at all, I have a few harder knives, around 63-65HRC and with normal use I can see rolls on them as well. See the photo and discussion below, in benefits section. In short it all depends on the steel, hardness and cutting medium plus the force used. What happens if you apply too much force on the harder knife can be seen on this photo of damaged Shun paring knife edge. Few chips and cracks are clearly visible and that’s just the tip section.

Whether the metal folds to the sides or chips, the edge is not as thin as it was before, and the surface area of the edge increases. It becomes duller, even though it still has all the original metal on it. Now, it takes more pressure or more force to make the same cut. Therefore, the deformed metal will be subjected to more stress and will deform even more. That’s the process and that is why the edges dull primarily. To make the knife sharp again, you have to make the edge straight again, and in more extreme cases, thin it down again. Obviously, chipped edge can not be helped with steeling or stropping, it requires sharpening, which is done with sharpening stone or any abrasive material, but not with a butcher steel.

What Steeling Is

– So, let’s start with what steeling is. The knife edge is swiped against a steel rod, also called a steel, also a butcher’s steel. The purpose and the effect, when it’s done correctly, is that the deformed edge gets realigned back to its straight state. As you can guess, steeling has no effect of the chipped edge, since there is pretty much nothing to push back and align. There is another problem with the very hard edges, such as the knives with the Rockwell hardness above 62-63HRC. Most of the butcher steels are made of the steel which is around 60-63HRC. So, if the knife is harder than the steel used for the steeling, then the harder edge will not be affected much. In those cases the ceramic or borosilicate rods should be used. They both have Rockwell hardness above 80s. In fact, it is recommended for ultra hard knives like Aritsugu 300mm Honkasumi Yanagiba at 65 HRC or Phil Wilson CPM-10V Knife 64HRC, or his CPM S125V knife at 65HRC. More about that in Ceramic Sharpener Reviews section.

As for the steeling how to, it’s pretty simple as long as you can hold consistent angle. They key is to try to match the angle you are holding the knife at the same angle as the edge angle. The usual advice is to hold the rod vertically and swipe the knife along it, as if you are making a cut. Very important to keel the light pressure. Once you get efficient, you can try other positions, whatever works best for you. Also, using a magic marker trick will help. Cover the edge with the marker, make a swipe or two and wherever the marker is gone that’s where you are hitting the edge. Adjust accordingly. If you are doing everything right, then all you need is 3-5 passes per side to realign the edge back, therefore the speed is pretty much irrelevant, unless you have a few hundred knives to steel in a row, or you’re trying to impress someone. If you need more that 5, or 10 at maximum strokes, then either you are not using correct angle, or the knife is too dull for steeling, like I said after several steeling sessions, those folds that get straightened will eventually break off. Once that happens the edge is permanently dull for steeling, that is no amount of rubbing on the smooth or borosilicate rods will restore its sharpness, and the same applies to the grooved steel, it won’t work. The only thing that will help at that stage is sharpening, i.e. actual removal of the metal to thin the edge down. Ceramic rods are sharpeners even when they are used for steeling, and they will do the job for some time, but once the edge gets too thick, something like this one, you’ll need to resort to coarser sharpeners, unless you plan to spend a day sharpening one edge with that ceramic stick.

What is stropping

– Well, it serves the same purpose, aligning the edge. However, it’s done by swiping the edge on the piece of the leather. Stropping normally is done on the plain leather, however loading the leather with an abrasive compound such as diamond paste or chromium oxide powder will make a fine sharpener. In fact I routinely use several different leather strops loaded with 0.5µm and 0.25µm diamond crystal spray as the final steps for sharpening, before I strop the finished blade on the plain leather strop. One thing to remember about stropping is that hard steel doesn’t respond very well to stropping on the plain leather. Again, we’re talking about the steel above 62-63HRC. For those cases use borosilicate or ceramic rods. Other than that, stropping is more effective for the blades below 62HRC. For the record, if we’re using abrasive compound on the strop, then it is not stropping and we’re not simply realigning the edge, but removing the metal, which is sharpening.

Stropping is done in the opposite way of steeling. In that the edge is dragged backwards, not pushed forward. The rest is absolutely the same. You use very light pressure, try to match the edge angle as precisely as you can, and you will be fine. Stropping is also very necessary and effective step after any sharpening. Magic marker helps again here, with the correct angle. If you have not done it[stropping] before, try it, it will dramatically improve sharpening results. Because, it removes weak very small pieces of metal, burr, straightens the edge making it more refined. I can talk all I want about that, but you’ll have to try it yourself to feel the difference in the result.

Benefits of steeling and stropping

– Steeling(or stropping) is the simplest and the quickest procedure that you can perform to maintain and extend the useful life of your edges, hence the knives themselves. Very simple procedure, however, unfortunately, most of the people never do it, others do it with a wrong tool, which arguably is worse than not steeling at all. I’m talking about the dreaded grooved steel, or butchers steel in other words that comes with every standard cutlery set sold in US and as far as I can tell, in the rest of the world as well. The ideal sequence would be to steel your knives before and after every use. Yes, before and after, and yes, every use. All you need is 2-3 passes per side. That’s it. Mark the timer, if that takes more than a minute. The benefits? Your edge, ok your knife’s edge, will last at least twice as long. If you’re so busy, then skip the after part, and steel the knife before every use. Still better than not doing it at all. See next about the pre/post steeling effects below.

Dave Martell, who is one of the best sharpening specialists in the US, recommends stropping over steeling, whenever conditions and environment permit. Pro-kitchen may not be the place to do regular stropping for example. However, as you can guess, stropping will achieve the same aligning effect, plus remove any loose/weak particles from the edge. In other words, it’s a more effective way to maintain the edge. Another note from Dave: On softer knives post (or after) use steeling doesn’t have good effect due to the metal relaxation or memory effect. In simple words, deformed metal, the edge in our case, tends to go back to the deformed state over time, when left alone, aligning the edge before its use, doesn’t give the edge time to go back to its deformations. Thus, steeling(better yet, stropping) before the use is the best way. According to other sources, post steeling still can have positive effect, minimizing the size/magnitude of the deformations. Complicated matter 🙂 For harder Japanese knives, the effects of post steeling aren’t as simple compared to softer western knives. And finally let’s actually see visually what happens with steeling and stropping.

Watanabe small nakiri edge in different stages of stropping and steeling

The top part of the attached photo shows the rolled edge of the Watanabe Kuro-Uchi Nakiri. The blade is shown in normal position, so the edge is down, and you can clearly see the shadow cast by rolled edge. Now let’s look at the bottom part of the same photo, you can see the realigned edge, which feels much sharper and it is in fact sharper. Which is why a lot of people mistake steeling with sharpening. The process is absolutely different, sharpening implies removal of the metal, while stropping/steeling does not, it just realigns the deformed metal, for the pedants, yes the small pieces of metal can and will be removed during steeling or stropping, but that is due to the metal fatigue, not because it was intended.

Also, if you read the notes on the photo, you’ll notice that it took 50 passes on a leather strop, which can be easily explained by extremely high hardness of the steel on Watanabe knives, 63-65HRC. Most of the alignment you see on the photo was done after just 5 passes per side on the Borosilicate rod. In the end, for softer knives few passes on leather strop will do, or on the smooth steel, whichever works better for you. For those ultra hard knives you need either ceramic or borosilicate rods.

So, in the end, steeling and stropping, although different procedures by themselves, both serve the same purpose and that purpose is to align the deformed edge of the knife. it is not sharpening, even though it makes the edge feel sharper, it is not sharpening, as its purpose is not removal of the metal, but realigning the deformations on the edge.

Last updated – 09/01/11

Very interesting and informative article about why your blades are all dull and what to do about it.


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