Why develop a false edge on purpose
Updated: Mar 27, 2020
Can a false or feather edge serve a purpose.
The back and forth strokes are the most common stroke used with tools and knives, and many razor honers do also use back and forth. This is a stroke that can be very good for you if you master it, so the stroke itself is not a negative issue. I use the back and forth strokes for plane blades, chisels, but for the final finishing I use edge leading strokes in order to reduce the development of a false edge.
My thinking and understanding is that when when two sides of a blade meet in perfect geometry the edge looks like a V , when they form a false edge it looks like a Y and a dull edge looks like a U . In my shop I will take a blade that is dull, develop a false edge on purpose, and then remove the false edge to create a sharp edge. So my sequence looks like U-Y-V.
When I hone a razor or chisel I try to create a Y profile because the tail of the Y is proof that the two sides have met each other. Then I take that Y shape, remove the tail and I am left with a V shape which I consider to be perfect geometry.
In my studies I have found that on a high quality Awasedo with slurry a forward edge leading stroke will quickly remove the feather like false edge with just the first few strokes. To add more strokes on the slurry stone is not better and here is the reason why. A stone with slurry builds a wave of slurry in front of the blade (front of edge in edge leading strokes—-front of spine in spine leading strokes) and this slurry has thickness and great cutting powers.
The thickness of the wave and the concentration of the slurry component will abrade and slightly convex the bevel beginning at the edge before and with less influence back away from the edge with edge leading strokes. In other words the blade at the edge is more directly affected by the slurry first and before the rest of the bevel is affected. This makes the blade slightly convex and the edge. The more strokes you add with slurry the rounder the blade gets, so when you go to your clear water stage the bevel is not flat anymore and the edge sits ever so slightly a little bit above the stone.
If the edge is sitting above the stone when you use the clear water strokes technique, this will begin to reduce this curvature and eventually the blades edge will touch the stone as the bevels becomes flat again. The trick here is to know, or to be able to feel or see that exact moment when the bevel is flat again and as the edge begins to touch the stone. At this point in the sequence the geometry is acute and depending on the abrasive, and your technique the edge will be as sharp as it will get from that stone. Going next to a strop can add refinement too but if you final edge retained some areas of the false edge this edge can be slightly dull after the false edge is broken or abrade off.
Forward edge leading strokes reduce the area or band width of feather/false edge, spine leading strokes promote the width of the false edge, back and forth strokes do both. With the very last stone, just before you strop your razor I suggest that you do edge leading strokes only because they reduce the formation of a false edge and promote direct contact between steel and stone.
I suggest that you, with purpose, build an excellent and useful false edge with perfect geometry, and then manipulate your technique with slurry as your secret agent, the surgical removal of that false edge without overdoing it. If you can do this, in the end you are left with an edge of solid steel that represents your perfect geometrically designed razors edge.
Example of the development of a razor edge
Click the picture to see more details
The photos above are dramatic, they were created in my workshop with ordinary and common stones and they help to illustrate how a razors edge can be manipulated, and how it is manipulated whether you know it is happening or not. The way I use a stone like the Okudo asagi is to make a diamond plate slurry lets say that looks like whole milk (not cream), and hone your razors bevels for how ever many strokes it takes to remove the previous scratches. It can be as few as 15 to 35 strokes. Next I use a tomonagura whole milk consistency slurry or slightly thinner, like skim milk for the same number of strokes. I always count so I know where I have been. To transcend to clear water I do this by when I am ready, I make a full pass with my razor and then rinse off the slurry that is on the blade in my water bath and I carry back to the hone the clear water that was left on the blade by the rinse. This water is now in play. I will do this several times until I am honing only on clear water. Then I strop 20x and test for HHT. If I pass fine, I can strop more or test shave. If it doesn’t pass I will try 10 more strokes on clear water, strop and test, if still no HHT I try stropping 10 more times. If it still fails HHT I will go back and do a full bevel bevel set again and go through the whole routine but using fewer strokes at each level. I find that a razor can fail both HHT and Shaving Test if a false edge was developed and either broken off crudely, or it just folded over. I always felt that adding more strokes is not the only answer, a few maybe but not a lot unless your stones are totally slow cutting. If you are using fast cutting stone then more strokes just removes more steel when the problem might actually be 1) your technique is poor, 2) you have developed a false edge and failed to remove it through gentle abrasion, 3) you geometry was off from the bevel set stage. The above assumes that you are using razor quality fast cutting stones. I have seen through my microscope what perfect geometry looks like, where the bevel setting scratches should lead all the way to the edge from the base of the bevel in long continuous scratch marks. If they do not reach the edge then the bevel is not set. If your scratches reach the edge as continuous scratches and you continue to hone a feather edge will develop but the razor does not get sharper and sharper after that point in time. If the razor did continue to get sharper the more strokes you add, then in theory the razor after 5,000 strokes would be sharper than after the first 1,000 or 100 strokes and we all know that this does not happen to be the case. I feel that there are sweet spots in time at all of the razor honing stages of bevel setting, edge refinement and edge finishing which includes those final few strokes and stropping. The development of the edge can fail to configure at any one of these stages, and fail independently of the previous or following stage. If you keep this in mind and if you have a regular method you can reverse engineer your technique and begin to eliminate your technical errors.
Posted on March 6, 2016 by Administrator If you are going to work on razors and knives you will want a broader selection of stones, mainly because of the size of the knives and because of the necessity of an ultimately keen razor. Razor stones are special because they are not only fine but they cut very fast, this is necessary because if they are not fine enough they will not shave well, and if not fast enough (highly gritted) with the light pressure we use when honing razors it would take too long for each razor. Knife stones are usually larger all around and will withstand a heavy handed routine necessary for knives, and knife stones are not normally as fine as razor stones because they first, do not need to be, and secondly the pounding and scraping that a knife edge goes through in normal use, a razor sharp edge will begin to breakdown within minutes. You were asking about a suita for razors, maybe a pre-finish stone. Honing a progression of stones for razors is necessary for restoration from bevel setting stages on up. Some of us have a two stone progression and go from 1k directly to a finishing stone, but many fellows use a nagua progression, a pre-finishing stone progression or even several stones lined up as a progression. I would suggest that a nagura progression that can include both Shiro Mikawa Nagura and or tomonagura slurry or elements of other stones would be considered to be the most professional standard. A progression establishes and maintains throughout the honing session an edge that is built on solid steel. The 1k to finisher does give a shave ready edge but it is so closely based on the 1k stones scratch pattern than there could be, in theory, structural factors that underlay that super keen edge that might create some jeopardy regarding the tenacity of the edge. A single stone that covers all of the tasks of: bevel setting razors, pre-finishing razors, finishing knive edges should be based on a knife stone model if you take into account the factors from above. This stone would be a medium hard stone that in the 5 or 5- range, very fine in the 5 range, sized to fit the type of knife, and easily maintained so it can be lapped for razors when necessary. The grit richness that determines speed could be in the 5 to 5+ range. Sharpening knives is a heavy process that with the right stone can go quickly especially if the stone, like one in a hardness range of the lower 5′s is used because the stone is sheds dull used grit particles while revealing newer sharp particles. This single stone could be a first step in building a flexible progressive stable of stones, one you could build around but it is unlikely that it will be your one and only middle range stone. I suggest that a tomae stone instead of a suita stone will feel the most comfortable under your razors and knives as “that single stone”. There is a page to my website that I have been developing but it is not yet linked to my website, it is devoted to knive stones and there is one stone there that you might want to try, #1103. This tomae is very smooth but cuts fast because it is grit rich but also medium hard. If you wanted to test it, with a deposit plus postage I could send both the #1103 and the suita #1108. Testing two stones side by side is very revealing, plus you have your Ozaki there already to test against these two others. I think it would be worth both of ours efforts to do this if you have the shop time to manage it in a week or 10 days. Each of the stones are priced and perform similar, and after testing you can send back one or both if you choose and all it will cost you is the round trip shipping in a Medium Priority box. I will always pay shipping for an outright purchase, but for testing the cost is on you. I have this same arrangement with a few other customers for different reason, but my main idea is to copy in my own way the way that these unique stones were retailed in Japan where the buyer/end user had a chance to bring his own tools or test his own razors on a group of stones to look for compatible combinations between his steel and their stone. The more you get into this the more you realize that with both natural and synthetic stone, there are symbiotic relationships between stone and steel. Almost any combination will almost always work, but combinations that really, really work well are special. The burden is on the stone to perform but the user is in the drivers seat, and when things click it takes a lot of stress out of the process and this allows the driver/user to not only get the same job done quicker but also allows him more flexibility to express technique and professional judgement calls. Busy shops who specialize in particular steels or techniques find it efficient to match up larger stones that have a longer shop life with the normal tasks that are specific to their work. Blacksmiths choose the steel they forge, but they also choose the stones in their shop tailored to their favorite steels, and stones that are thick will have a longer shop life thus minimizing the burden of shopping for and testing replacement stones when their old ones get thin. Natural or synthetic is not the point, it is efficiency and quality that is primary. Not every stone works for every steel but for a smith or sharpening shop, they narrow down the possibility of failure or loss of production time by repeating past good experiences with certain combinations and repeat those over and over again. Like with antique Sheffield steel softer stones tend to work better and 20th C. German steel benefits by using harder stones. It can even fine tuned down to certain blade makers all though not usually necessary unless you are working with that blade smith directly.
The nature of Tomonagura and using a Diamond Nagura
Posted on December 30
Hello Tim I do hope that you get the Okudo soon and that you like the tomonagura that I included. Without handling the tomo that you got from someone else, I wonder how mine would match up against the others. Mine might be just as soft so keep me posted. Matching tomo requires having enough tomo samples to test with, and it is a little confusing too. In my own shop I relay a lot on a well worn Atoma #600 to perform the same work that some fellows use Botan and Mejiro for, refining the bevel after my 1k or 2k bevel setting stone. The diamond generated slurry is really fast cutting and I find it leaves the bevels in a very good state as the DN (diamond nagura) slurry crumbles from the bundled grit particles made from the DN down to smaller and finer individual grit particles. Using the DN slurry sets the stage for the tomo, and a tomo following the DN slurry has a much easier job. The trick in matching a tomo falls into that narrow realm, picking out a tomonagura that does not deeply scratch the base stone, but is hard enough to abrade it slightly. Some of the burden on the user is to adjust his/her hand pressure, water content and stroke speed to prevent scratching. With really hard stones this all becomes more critical, and as a matter of fact the same holds true with honing really hard steels on really hard stones. As a purveyor of stones I often have to err on the side of a slightly softer tomo that demands less of the base stone as a slurry source, and this can seem like a miss-match, and I would have to agree if you had to go with your blade directly from the 1k bevel setter to the tomo and the base stone with no intermediate grit source. Going back to my shop, this is where the DN comes into play. A DN slurry covers a lot of difficult ground when working with very hard stones, it is like a Botan-Tenjyou-Mejiro progression all in one slurry. I find that most users of Asano stamped Shiro Mikawa Nagura do not finish their razors with those 3 or 4 softer stones, they almost always finish with a tomonagura, and then often followed by a clear water polish. If accepting the proposition where the DN slurry can replace the Mikawa progression, then there is at alternate method leading to the tomonagura, and if the tomo has a ultra fine grit particle matrix that at least equals that of the base stone in fineness, then in practice a slightly softer tomo can bridge that gap between the DN slurry and the clear water stage because the DN slurry has already relieved so much burden after the bevel set. This of course is all predicated that you have a super fine grit particle tomo. I think that you will find the two tomo I enclosed in the package to be super fine, but as I began with they might be too soft to bridge the gap between 1k and clear water finish alone, if not try adding a DN element in there and see how that works out. The diamond plate will have to have meet the same criteria as the tomo, one that does not leave deep scratches, so a worn out plate works best. If your plate does leave scratches I think that you might be surprised in the long run how little the negative effects actually are and that those same scratches might be worn down by the end of your honing session. One more thing. It is cited that a diamond plate prematurely wears out a valuable on of a kind awasedo stone if you use it to raise a slurry. I would be a fool to suggest otherwise. But my choice to use a DN is based on balancing that tiny 50 microns thin skin of that surface sacrificed versus ignoring the superior cutting power of an otherwise very slow cutting hard stone that neither I or my son will ever wear out no matter if a diamond plate slurry is used of not. Almost everyone now used a diamond plate to flatten their stones, and then they just wash away that slurry down the drain. Many fellows flatten their stones before each use and wash away that slurry. If you do this, next time don’t rinse it away, try using it. Honing razors is really just a craft, and you can use the word compromise, or adjustments as an integral necessity of the craft. TheAxMethod pares down the stroke count, and treats both sides of the razor equally as a way of minimizing errors that are difficult to track down later. If you edges are sharp enough to shave with, than the ultimately sharp edge is just whispers away, maybe as few as 5 strokes more or less, pressure (more or less), or in the stropping. Focus on those instead of adding groups of 40 or 75 or a 1000 more strokes. The more strokes the better is not a true statement, if it was than 20,000 more strokes would still not be the ultimate. The truth is that these is a plateau in the number of strokes where the greatest and finest finish that any given stone will max out. The secret is to learn how to recognize this state of development, and to stop there and move on to another abrasive or another method. Alx