A Comparison of Several Manufactured Blades
Grit, Scratches and Sub-Surface Damage – Part 1
Seven Misconceptions about Knife Burrs
What Does Steeling Do? (part 1)
What Does Steeling Do? (part 2): The Card Scraper
Abrasive Particles Under the SEM
Optical vs Electron Microscopy
Diamond Plate break-in – part 1
Diamond Plate break-in – part 2
scienceofsharp 
172 responses to “Index”
Hey Todd, I’m a 17 year old knife sharpener in high school, and I’m taking a class called AP Research. I hope to focus my project on the influence of sharpening on fine edge holding with high carbide steels. I want to reach out to the colleges near by in hopes they might let me take a couple S.E.M. images with their microscope.
It’s quite safe to say that this aspiration to include actual S.E.M. images in my high school research project is lead purely on blind curiosity and interest in my topic, and not any sort of idea towards what might go into this process. I feel very unprepared, and I think it might be helpful if I knew exactly what to ask for before I asked. I also think letting colleges know that I already discussed the procedure with someone experienced would help my chances of getting a yes. I wanted to see if you had any helpful tips or if you could allude towards what the process might actually look like before I reach out. If you could email me back, that would be extremely helpful.
Thank you Todd,
I really appreciate it.
Ben
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HI Ben
Awesome interest. You will be able to come up with some great images of your own just using a regular microscope with a digital camera insert and taking screen shots. Playing with the focus, depth of field, lighting angles and so on to get good detail in your images will also be something worthwhile. You will also be able to control variables and examine a specific thing or two with microscopic knowledge and images of your own.
Todd’s SEM images are something special as they are professionally controlled and processed.
All the best with your investigations.
Cheers David
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Thanks a lot David,
I have a microscope that I’m using, and it’s pretty high magnification (4x-1000x which is plenty) the trouble I am having is getting the image to be clear. It’s not a digical microscope, this microscope has a light on the bottom for viewing cells in glass blanks. I need to hold the knife at the right angle, and setup the flashlight to get light on top of the edge, and then focus with the knobs to get an image. It’s a work in process but already it’s proving extremely helpful. Sometimes the image looks unclear, even when in focus (I think) because of the lighting. I will see if I can get a book light or something. Regardless, thank you so much for your reply. If I have any more questions I will leave them here.
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Sounds like a fun project. I don’t mean to discourage you, but imaging blades successfully with SEM is quite difficult. One of the biggest challenges is that they have to be extremely clean, otherwise you will only image oil on the surface. Also, most microscopes aren’t large enough to accommodate a knife. I normally use pieces of blades, or just the blades from small folding knives. Instead, you may have better success borrowing some time on a research-quality optical microscope (with a camera).
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Hey Todd,
A professor of microscopy at a nearby college has agreed to let me use their SEM microscope for my project. If you could email me @ benspaloss@gmail.com within the next two weeks it would make a serious difference in making this opportunity come to fruition.
Todd, I care about research in knife sharpening more than I care about anything else. It is my dream to have a site like this. It is my dream to do work like you do. I know you probably don’t have your contact info public for a reason, but sincerely it would mean the world if you could offer some guidance.
Regardless,
Thank you for the work you have done,
Ben
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Dear scienceofsharp.
U r the grand master of sharpening.
I appreciate for ur study and letting me know the study.
This is exactly what tortured me for several years.
The approach is so nice. S.E.M. I have never ever dream of SEM.
I’m reading the articles over and over again.
But I have some difficulties to understand it.
I don’t know what the term “micro-chipping’ means.
Would u correct my misunderstanding?
1. grain from stone when abrasion / will make some debris from the blade. is the debris micro-chipping?
2. is the debris(from 1) which break the blade edge / micro-chipping?
3. is the grain from water stone which break the blade edge / micro-chipping? (grit + steel = swarf)
4. is the steel debris from blade edge by abrasion / micro-chipping?
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Hi Todd I’ve been working for 2 years on making sharp knife edges on various steels, would you be interested in doing some purpose-driven microscopy? Happy to have a call. Sorry if this note is in the wrong venue…
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I do provide imaging for a fee through my laboratory / employer.
email scienceofsharp@scienceofsharp.com for more information.
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What would you think is the next best material if I don’t have denim for the hanging strop with metal polish? This is for knife sharpening! Thanks!
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Any heavy woven fabric should work, maybe canvas from a drop cloth. A couple of sheets of printer paper on a hard surface is nearly as efficient if you can find a suitable fabric.
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Hi todd. I just was wondering after all this information if you could help me out if you have time please. Sharpening knives what would you use to sharpen them. What stones? And what stropping means (leather, wood, fabric etc) and in what order? And the amount of strokes on the strop and what type of compound. I have been using a king combination stone 1000/6000 but I have noticed that veritas stropping compound dulls the polish on the edge after the 6000 grit stone but the blade is then sharper. Does that mean that the stropping compound is not as fine as the stone? I’ve heard its not that great?
Thank you mate you’re doing an amazing job
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Forget you ever heard about “grit” and “polish” and just find/choose a way to determine when you knives are sharp enough. I like to to feel the edge with my thumb, but test cutting paper works too.
Virtually any stone can get you 98% of the way, certainly the King 1k/6k can. The Veritas compound is as good as any, I’d just put it on a piece of denim. I do 30 laps as a habit, but not much happens after the first 3.
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Todd – I’ve seen you recommend a few times on different forums to strop with .25/.5 micron diamonds on leather, without regard to prior steps. But your Simple Straight Razor Honing technique suggests that doing so before microconvexing the edge will leave behind a foil edge.
If my sharpening process uses a jig and doesn’t include the microconvexing step on pasted denim, it supposedly leaves behind a triangular edge. Is it the right move for me to strop on plain leather instead of pasted leather?
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It’s really only an issue for straight razors, first because the angle is so low that the burr doesn’t get bent that far and survives longer, and second the spine ensures you are stropping at the same angle as you were on the stone.
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Understood. This seems to suggest that the metal polish on denim step is unnecessary for knives. Is that correct?
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I try to avoid making generalizations, but I would be more likely to use the denim/polish for a knife that has been sharpened at lower angles and coarser abrasives to remove the damaged metal from the apex region.
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Dear, Your picture of Jnat slurry help me a lot to understand honing with Japanese stones. Do you have similar pictures of Coti slurry so we can compare the form of particles?
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The header image is Coticule slurry. The matrix (clay) is basically the same as with JNat type stones, but the (garnet) abrasives are slightly bigger, but also less “sharp” I suspect that the larger inclusions in both those type of stones play a significant role as well.
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Just excellent.
Any plans for an extended series on kitchen knife sharpening?
I can think of so many hypotheses…
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For kitchen knife sharpening, the one thing I have learned on here is that when steeling your knife do edge trailing strokes, like stropping. Every tutorial and video online says to to edge leading, but that does not make one drip of sense. Edge trailing only. You’ll be slicing those tomatoes like a pro.
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Hey Todd,
I was recently introduced to your website from Larrin over at knife steel nerds and I absolutely love it already!
A few years back I found this article that showed by using honing oil it actually suspends the metal shavings and creates micro nicks in the blade whereas using water didn’t create such occurrences. I have been unable to find it again and I was wondering if you could recreate it
John
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“micro nicks” is almost always what we see when there is a foil burr. See for example the edge from a DMT 600. It isn’t surprising that a better lubricant leads to larger foil burrs.
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It looks like the Index (/home/) page does not contain links to all articles. Does wordpress not allow to create a proper index page listing everything? It would be very nice to have for easier navigation (as compared to reading page by page). Sorry if it exists and I just fail to find it.
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The index page was created manually to group articles by topic rather than by date. I wasn’t aware that I had I missed adding any.
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Thanks for all your work here!
For knife sharpening, am I understanding correctly that varying the stropping angle by raising the blade can achieve a similar effect to diamond on denim/linen as diamond on leather (with regards to forming the micro-convex and avoiding foil edge formation)?
Also, do you have any thoughts or experience on the nanocloth strops from Jende?
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Let me say that the content on this website launched my sharpening into a whole other level. I have the hands, just not the brains (or time) to figure all this out on my own. So, thank you a million times! I want to pass along this skill at a local makerspace, would you be alright with me using your images in a lesson presentation to help explain sharpening a bit better? I also would love to quote you on how you explained sharpness and keenness, I can’t word it as succinctly. Thanks again!
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Hi, did somebody know someting about this sharpening device? For me it sounds like an old times läpping thinggy.
https://antiques-atlas.com/antique/a_19th_century_welsh_pine_knife_sharpening_board/as1019a023
I have seen a picture in german shaving forum before. It should be possible to get a razor sharp edge. I find this link over the google picture search tool.
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In some parts of this world this technique is still in use.
I found two videos on YT, where its shown.
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Hello! I see the last article was posted in sep 2021. I think its time for a new one.
Here are some ideas:
Does carbon steel actually get sharper than stainless with common sharpening stones? Maybe test with razors and a BESS tester? Or is it possibly “easier” to get it to a certain sharpness.
Does high carbide (4% V or similar and up) steel stay sharp longer when sharpened on diamonds vs regular stones?
Can GEM blades be successfully resharpened, and whats the best process for this?
What were the hardness and HT process of antique razors?
Whats the lowest grit stone someone could actually use to shave?
What would the ultimate DE/GEM razor geometry look like?
🙂
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Unfortunately, I have more ideas for articles than I have motivation for writing them.
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I totally understand that.
But for the record you are doing amazing stuff for a very niche crowd. The couple hundred readers you have following your work are in awe and super appreciative of your content.
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Your content is of great value.
Probably not easy to understand for a “normal” blade enthusiast, however this is certainly not attributable to the format, which I find perfect. These are technical topics, which require the reader to concentrate and have a certain amount of effort, I see no other way.
The web is full of youtubers showing how to move a razor over stones. Your studies, on the other hand, are unique in terms of rigor and clarity of presentation.
I’m sorry I never thanked you before, I do now.
Thank you, thank you very much!
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Todd, I just wanted to say that you’re awesome. Thank you so much for your work.
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I also want to thank you for your work. I’m rereading your articles now and still find them remarkably interesting and useful.
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(clicked on the wrong “Reply” button – that was to Todd, obviously)
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I find it fascinating that what seems a tiny mole per cent of an alloying constituent can have a significant effect on properties. I would like to dig into the chemistry of alloyed steel, especially blade steels that, besides chromium, have only modest amounts of other constituents. Can you recommend a book that deals on a fundamental level how these minor constituents are incorporated into the steel and how they do what they do to affect properties?
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You’ll find what you need at the Knife Steel Nerds website, and his book is exactly what you’re looking for..
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I have a question, accourding to this Japanese Master a shiny finish tent chip earlier, did somebody know where i can read more about this?
I allways thought that the finnesh polished blade is the best, like „Blaupließten“ of the world famous Solinger knifes?
Did the old master know more than science can find out?
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