Lately I've been asked about the subject of burr removal quite a bit more than any other time in the past. This is a timely coincidence for me due to me own testing that I've been doing. Since many of you have questions I thought I'd share my current thoughts on this issue.
As most know I'm a professional knife sharpener. I've done a lot of sharpening of many types of tools using many types of equipment. Over the last 4 years or so I've been trying to reduce my dependency for powered tools when sharpening Japanese knives. Admittedly this hasn't been easy (for several reason) mostly due to the demand on me to make repairs. In the process of my work I've sharpened A LOT of Japanese knives, many more than I thought existed. I've learned an incredible amount by keeping my mind open and paying attention to details, and challenging everything I believe in and what others say. With all this I've been able to make some solid conclusions but made many more questions in other regards. For me, the issue at hand is to not just take an edge to the ultimate level of sharpness it is to also make it as strong as can be. These two ideals never seem to meet without an extensive amount of work and I'll explain this is a minute. I hope that you get the idea of what I'm trying to accomplish when I sit down with the stones - it's a super sharp, yet super tough, edge I desire.
OK, now that's out of the way, I'll start by talking about what I've found and how I deal with it.
Way back when I first started sharpening Japanese knives I didn't understand a lot of things and often relied on powered equipment for burr removal. Since I was familiar with wheels and belts this became an easy way to deal with problematic burr removal which I often see with Japanese knives. The truth is that the cheapest and best knives are the worst when removing burrs. I've always tried to address this problem in non powered ways but could never produce the same results without a belt or wheel. Since partnering up with HandAmerican I've had the oppurtunity to try many different products and techniques. I try soooooo many new things that Keith comes up with you'd be amazed to hear of them and I try them over time before making any snap decisions. This was different with the HA felt pad though as I found instant success with this by accident and I've continued to like it ever since.
My trials and errors, to this point, have led me to the following conclusions...
*Note - This only applies to Japanese knives. Euro/American knives react completely different.
1. There are two major things to deal with on Japanese knives if you want a strong edge. The first are the burrs and the second is the wire edge.
2. More than 98% of us here remove burrs by reducing them through use of polishing stones and/or drawing them off through slicing into objects like woood (etc) - but - this does not work entirely as we would expect it to.
3. Removing/reducing loose burrs in this fashion is great but it should be done early in the process rather than at the end of the process.
4. Reducing the burr by polishing it away leaves behind a very sharp polished weak wire edge - not a strong cutting edge as desired.
5. The burrs created on Japanese knives are very resilient and do not want to break away easily so the thought is to abrade them away. My thought is that by abrading them away they get in the way of reducing the wire edge so reducing them is a flawed concept.
6. This wire edge can only be reduced if the burrs are removed early in the sharpening process like after every coarse/medium stone that has the ability to create a burr in even the smallest amount. This means that the burrs should be removed before the reducing of the wire edge is attempted.
One of the things that's always troubled me is that the Japanese don't deal with this issue and how can they not? I've come to the conclusion that we might be asking more from these knives then they are. I don't have the experience to make any statements on this but I suspect they keep their knives sharp though frequent touch ups rather than full on burr creating sharpening sessions like we often do.
I know right now many of you are shaking your heads saying, "I don't have a burr removal problem and I never have a wire edge problem" and I agree with you that you don't, that is you don't until you can see it for yourself.
I've handled hundreds of knives where the owner/sharpener claims that their knives don't have this problem when in fact they do. I've done experiements over and over again to prove to myself and others that this wire edge condition exists and the results are always the same.
Case in point - just the other night I spent 3.5 hours sharpening and testing on my new Watanabe nakiri trying to get a good strong edge on it. This all started because I first sharpened it (the night before) trying to create the ultimate sharp edge by bringing the two plains together perfectly to create the scariest edge ever. I sharpened the knife as usual and did not deburr untilt the end using a leather pad. It felt sharp as hell but I could still detect a wire edge (as usual). I accomplished this great super extra sharp edge but when I used it the first time the edge crumbled almost immediately and looked like all the edges I see come in every day for work. I took this knife back out to the truck and put it on the leather belt just to see what would happen. In an instant (the second the knife touched the belt) the whole edge flipped to the opposite side like a giant burr that hadn't been removed. Guess what this was I was looking at? If you're thinking "wire edge" then you're correct. BTW - I often do this same test to knives of people who claim that they don't have wire edges or burr issues and guess what I find? You know what I find.
The 3.5 hour sharpening session followed these findings and I tried every trick in the book until I was right back to removing the burr following the coarse/medium stones. Guess what? N The crumbling edge disappeared and it's still sharp as hell.
So my suggestion, to those of you who desire to not only have the sharpest edge but the strongest edge as well, is the following...
1. Create a burr.
2. Remove the burr after each and every stone that will make a burr.
Do so by not just using a felt pad but also drawing/slicing the edge through wood, cork, rubber, or even a corner/or end of a felt pad (which is what I do but I get free scraps to play with).
3. Create a dual bevel edge.
I'm talking about that old microbevel we hear so much about. Just one degree of angle loss on each side will do incredible things for your edge without (if done correctly) any loss in sharpness.
Create the microbevel (primary edge bevel) when using your polsihing stones starting with the first polishing stone you have. An example would be if using Glasstones the 4k or if Shapton Pros it would be the 5k.
4. If you have leather - use it.
I've yet to see an edge that can't be improved upon in from using a quality leather hone (charged with chromium oxide).
Leather will align the mirco-teeth, and if you're lucky (yes I'm saying this so sit down) it'll also slightly round your edge just a wee bit adding strength. This is a good trade off in my eyes.
Use your leather pad following your finest stone you have and if needed return to your finest stone and leather pad over and over again until you can not detect the wire edge anymore.
5. Stop using the 3 finger test.
I've fallen victim to this test but I'm now reformed and have seen the errors of my ways.
The three finger test is flawed. It will allow a ratty 120x DMT edge to pass flying colors while failing the crispest 5-30k edge. It will also fail a convex edge or stropped edge everytime. In my opinion it's a good tool to use to help you on your way but certainly not the ultimate guide to follow towards acheiving the best edge possible.
6. If you must use your fingers to test the edge then test for the wire edge.
This is very simple to do but for some reason 9 out of 10 people can't seem to do it. Keep it simple and let your finger tips roll off the side of the blade and edge and try to feel for a curled lip or for that matter anything. You want to feel nothing at all as your fingers rolls off the edge and if you even think (even the slightest thought) that you felt something then you have a wire edge. Be honest with yourself or you won't gain a thing from this.
7. Stop using jigs or sharpening devices.
These devices allow for the perfect situation for a wire edge to be created. They develop the perfect union between two planes (bevels) but in doing so leave a very weak edge. They do not allow for the slight hand control deviations (a very good thing) that helps with reducing the wire edge especially with regards to microbevel creation and the blending between the secondary and primary bevels.
If you must use these devices then I strongly suggest incorporating the use of the burr removal technqiues I explained above.
8. Test your edges.
I don't mean just test them on paper but on the items that the knife is intended to cut. It's almost impossible for me to make task specific edges on knives other than yanagibas (etc) but you can certainly tweak your edges to be exactly what you need them to be.
The best test, IMHO, that can be done is to test your edges for weakness (wire edges). This is where the BS meets the highway.
Take your newly sharpened edge and smash the edge down onto your cutting board a few times (like swinging a hammer) using far more force than you're comfortable with. If the edge crumbles, chips, folds, or blows apart then you've got issues. What you want is an edge that can be used hard but still remains plenty sharp as well as can be stropped back into shape. *Note - I offer no guarantees that my edges pass your slamming edge tests.
Yes, this is a somewhat destructive test (I understand) and not all of you will have the stones for this but I suggest you give it a go and curse me if you must because in the end you can learn to make stronger edges as a result.
In closing I'd like you to understand that these are simply observations, opinions, and suggestions that you can take for whatever they might be worth to you. I mean no harm to anyone in what I say here and offer this as a guide to helping you get to a better edge by sharing my thoughts and experiences with you. Hope this helps.